Class StringUtils


  • public class StringUtils
    extends Object

    Operations on String that are null safe.

    • IsEmpty/IsBlank - checks if a String contains text
    • Trim/Strip - removes leading and trailing whitespace
    • Equals - compares two strings null-safe
    • startsWith - check if a String starts with a prefix null-safe
    • endsWith - check if a String ends with a suffix null-safe
    • IndexOf/LastIndexOf/Contains - null-safe index-of checks
    • IndexOfAny/LastIndexOfAny/IndexOfAnyBut/LastIndexOfAnyBut - index-of any of a set of Strings
    • ContainsOnly/ContainsNone/ContainsAny - does String contains only/none/any of these characters
    • Substring/Left/Right/Mid - null-safe substring extractions
    • SubstringBefore/SubstringAfter/SubstringBetween - substring extraction relative to other strings
    • Split/Join - splits a String into an array of substrings and vice versa
    • Remove/Delete - removes part of a String
    • Replace/Overlay - Searches a String and replaces one String with another
    • Chomp/Chop - removes the last part of a String
    • LeftPad/RightPad/Center/Repeat - pads a String
    • UpperCase/LowerCase/SwapCase/Capitalize/Uncapitalize - changes the case of a String
    • CountMatches - counts the number of occurrences of one String in another
    • IsAlpha/IsNumeric/IsWhitespace/IsAsciiPrintable - checks the characters in a String
    • DefaultString - protects against a null input String
    • Reverse/ReverseDelimited - reverses a String
    • Abbreviate - abbreviates a string using ellipsis
    • Difference - compares Strings and reports on their differences
    • LevensteinDistance - the number of changes needed to change one String into another

    The StringUtils class defines certain words related to String handling.

    • null - null
    • empty - a zero-length string ("")
    • space - the space character (' ', char 32)
    • whitespace - the characters defined by Character.isWhitespace(char)
    • trim - the characters <= 32 as in String.trim()

    StringUtils handles null input Strings quietly. That is to say that a null input will return null. Where a boolean or int is being returned details vary by method.

    A side effect of the null handling is that a NullPointerException should be considered a bug in StringUtils (except for deprecated methods).

    Methods in this class give sample code to explain their operation. The symbol * is used to indicate any input including null.

    #ThreadSafe#

    Since:
    1.0
    Version:
    $Id: StringUtils.java 1058365 2011-01-13 00:04:49Z niallp $
    See Also:
    String
    • Constructor Detail

      • StringUtils

        public StringUtils()

        StringUtils instances should NOT be constructed in standard programming. Instead, the class should be used as StringUtils.trim(" foo ");.

        This constructor is public to permit tools that require a JavaBean instance to operate.

    • Method Detail

      • isEmpty

        public static boolean isEmpty​(String str)

        Checks if a String is empty ("") or null.

         StringUtils.isEmpty(null)      = true
         StringUtils.isEmpty("")        = true
         StringUtils.isEmpty(" ")       = false
         StringUtils.isEmpty("bob")     = false
         StringUtils.isEmpty("  bob  ") = false
         

        NOTE: This method changed in Lang version 2.0. It no longer trims the String. That functionality is available in isBlank().

        Parameters:
        str - the String to check, may be null
        Returns:
        true if the String is empty or null
      • isNotEmpty

        public static boolean isNotEmpty​(String str)

        Checks if a String is not empty ("") and not null.

         StringUtils.isNotEmpty(null)      = false
         StringUtils.isNotEmpty("")        = false
         StringUtils.isNotEmpty(" ")       = true
         StringUtils.isNotEmpty("bob")     = true
         StringUtils.isNotEmpty("  bob  ") = true
         
        Parameters:
        str - the String to check, may be null
        Returns:
        true if the String is not empty and not null
      • isBlank

        public static boolean isBlank​(String str)

        Checks if a String is whitespace, empty ("") or null.

         StringUtils.isBlank(null)      = true
         StringUtils.isBlank("")        = true
         StringUtils.isBlank(" ")       = true
         StringUtils.isBlank("bob")     = false
         StringUtils.isBlank("  bob  ") = false
         
        Parameters:
        str - the String to check, may be null
        Returns:
        true if the String is null, empty or whitespace
        Since:
        2.0
      • isNotBlank

        public static boolean isNotBlank​(String str)

        Checks if a String is not empty (""), not null and not whitespace only.

         StringUtils.isNotBlank(null)      = false
         StringUtils.isNotBlank("")        = false
         StringUtils.isNotBlank(" ")       = false
         StringUtils.isNotBlank("bob")     = true
         StringUtils.isNotBlank("  bob  ") = true
         
        Parameters:
        str - the String to check, may be null
        Returns:
        true if the String is not empty and not null and not whitespace
        Since:
        2.0
      • clean

        public static String clean​(String str)
        Deprecated.
        Use the clearer named trimToEmpty(String). Method will be removed in Commons Lang 3.0.

        Removes control characters (char <= 32) from both ends of this String, handling null by returning an empty String ("").

         StringUtils.clean(null)          = ""
         StringUtils.clean("")            = ""
         StringUtils.clean("abc")         = "abc"
         StringUtils.clean("    abc    ") = "abc"
         StringUtils.clean("     ")       = ""
         
        Parameters:
        str - the String to clean, may be null
        Returns:
        the trimmed text, never null
        See Also:
        String.trim()
      • trim

        public static String trim​(String str)

        Removes control characters (char <= 32) from both ends of this String, handling null by returning null.

        The String is trimmed using String.trim(). Trim removes start and end characters <= 32. To strip whitespace use strip(String).

        To trim your choice of characters, use the strip(String, String) methods.

         StringUtils.trim(null)          = null
         StringUtils.trim("")            = ""
         StringUtils.trim("     ")       = ""
         StringUtils.trim("abc")         = "abc"
         StringUtils.trim("    abc    ") = "abc"
         
        Parameters:
        str - the String to be trimmed, may be null
        Returns:
        the trimmed string, null if null String input
      • trimToNull

        public static String trimToNull​(String str)

        Removes control characters (char <= 32) from both ends of this String returning null if the String is empty ("") after the trim or if it is null.

        The String is trimmed using String.trim(). Trim removes start and end characters <= 32. To strip whitespace use stripToNull(String).

         StringUtils.trimToNull(null)          = null
         StringUtils.trimToNull("")            = null
         StringUtils.trimToNull("     ")       = null
         StringUtils.trimToNull("abc")         = "abc"
         StringUtils.trimToNull("    abc    ") = "abc"
         
        Parameters:
        str - the String to be trimmed, may be null
        Returns:
        the trimmed String, null if only chars <= 32, empty or null String input
        Since:
        2.0
      • trimToEmpty

        public static String trimToEmpty​(String str)

        Removes control characters (char <= 32) from both ends of this String returning an empty String ("") if the String is empty ("") after the trim or if it is null.

        The String is trimmed using String.trim(). Trim removes start and end characters <= 32. To strip whitespace use stripToEmpty(String).

         StringUtils.trimToEmpty(null)          = ""
         StringUtils.trimToEmpty("")            = ""
         StringUtils.trimToEmpty("     ")       = ""
         StringUtils.trimToEmpty("abc")         = "abc"
         StringUtils.trimToEmpty("    abc    ") = "abc"
         
        Parameters:
        str - the String to be trimmed, may be null
        Returns:
        the trimmed String, or an empty String if null input
        Since:
        2.0
      • strip

        public static String strip​(String str)

        Strips whitespace from the start and end of a String.

        This is similar to trim(String) but removes whitespace. Whitespace is defined by Character.isWhitespace(char).

        A null input String returns null.

         StringUtils.strip(null)     = null
         StringUtils.strip("")       = ""
         StringUtils.strip("   ")    = ""
         StringUtils.strip("abc")    = "abc"
         StringUtils.strip("  abc")  = "abc"
         StringUtils.strip("abc  ")  = "abc"
         StringUtils.strip(" abc ")  = "abc"
         StringUtils.strip(" ab c ") = "ab c"
         
        Parameters:
        str - the String to remove whitespace from, may be null
        Returns:
        the stripped String, null if null String input
      • stripToNull

        public static String stripToNull​(String str)

        Strips whitespace from the start and end of a String returning null if the String is empty ("") after the strip.

        This is similar to trimToNull(String) but removes whitespace. Whitespace is defined by Character.isWhitespace(char).

         StringUtils.stripToNull(null)     = null
         StringUtils.stripToNull("")       = null
         StringUtils.stripToNull("   ")    = null
         StringUtils.stripToNull("abc")    = "abc"
         StringUtils.stripToNull("  abc")  = "abc"
         StringUtils.stripToNull("abc  ")  = "abc"
         StringUtils.stripToNull(" abc ")  = "abc"
         StringUtils.stripToNull(" ab c ") = "ab c"
         
        Parameters:
        str - the String to be stripped, may be null
        Returns:
        the stripped String, null if whitespace, empty or null String input
        Since:
        2.0
      • stripToEmpty

        public static String stripToEmpty​(String str)

        Strips whitespace from the start and end of a String returning an empty String if null input.

        This is similar to trimToEmpty(String) but removes whitespace. Whitespace is defined by Character.isWhitespace(char).

         StringUtils.stripToEmpty(null)     = ""
         StringUtils.stripToEmpty("")       = ""
         StringUtils.stripToEmpty("   ")    = ""
         StringUtils.stripToEmpty("abc")    = "abc"
         StringUtils.stripToEmpty("  abc")  = "abc"
         StringUtils.stripToEmpty("abc  ")  = "abc"
         StringUtils.stripToEmpty(" abc ")  = "abc"
         StringUtils.stripToEmpty(" ab c ") = "ab c"
         
        Parameters:
        str - the String to be stripped, may be null
        Returns:
        the trimmed String, or an empty String if null input
        Since:
        2.0
      • strip

        public static String strip​(String str,
                                   String stripChars)

        Strips any of a set of characters from the start and end of a String. This is similar to String.trim() but allows the characters to be stripped to be controlled.

        A null input String returns null. An empty string ("") input returns the empty string.

        If the stripChars String is null, whitespace is stripped as defined by Character.isWhitespace(char). Alternatively use strip(String).

         StringUtils.strip(null, *)          = null
         StringUtils.strip("", *)            = ""
         StringUtils.strip("abc", null)      = "abc"
         StringUtils.strip("  abc", null)    = "abc"
         StringUtils.strip("abc  ", null)    = "abc"
         StringUtils.strip(" abc ", null)    = "abc"
         StringUtils.strip("  abcyx", "xyz") = "  abc"
         
        Parameters:
        str - the String to remove characters from, may be null
        stripChars - the characters to remove, null treated as whitespace
        Returns:
        the stripped String, null if null String input
      • stripStart

        public static String stripStart​(String str,
                                        String stripChars)

        Strips any of a set of characters from the start of a String.

        A null input String returns null. An empty string ("") input returns the empty string.

        If the stripChars String is null, whitespace is stripped as defined by Character.isWhitespace(char).

         StringUtils.stripStart(null, *)          = null
         StringUtils.stripStart("", *)            = ""
         StringUtils.stripStart("abc", "")        = "abc"
         StringUtils.stripStart("abc", null)      = "abc"
         StringUtils.stripStart("  abc", null)    = "abc"
         StringUtils.stripStart("abc  ", null)    = "abc  "
         StringUtils.stripStart(" abc ", null)    = "abc "
         StringUtils.stripStart("yxabc  ", "xyz") = "abc  "
         
        Parameters:
        str - the String to remove characters from, may be null
        stripChars - the characters to remove, null treated as whitespace
        Returns:
        the stripped String, null if null String input
      • stripEnd

        public static String stripEnd​(String str,
                                      String stripChars)

        Strips any of a set of characters from the end of a String.

        A null input String returns null. An empty string ("") input returns the empty string.

        If the stripChars String is null, whitespace is stripped as defined by Character.isWhitespace(char).

         StringUtils.stripEnd(null, *)          = null
         StringUtils.stripEnd("", *)            = ""
         StringUtils.stripEnd("abc", "")        = "abc"
         StringUtils.stripEnd("abc", null)      = "abc"
         StringUtils.stripEnd("  abc", null)    = "  abc"
         StringUtils.stripEnd("abc  ", null)    = "abc"
         StringUtils.stripEnd(" abc ", null)    = " abc"
         StringUtils.stripEnd("  abcyx", "xyz") = "  abc"
         StringUtils.stripEnd("120.00", ".0")   = "12"
         
        Parameters:
        str - the String to remove characters from, may be null
        stripChars - the set of characters to remove, null treated as whitespace
        Returns:
        the stripped String, null if null String input
      • stripAll

        public static String[] stripAll​(String[] strs)

        Strips whitespace from the start and end of every String in an array. Whitespace is defined by Character.isWhitespace(char).

        A new array is returned each time, except for length zero. A null array will return null. An empty array will return itself. A null array entry will be ignored.

         StringUtils.stripAll(null)             = null
         StringUtils.stripAll([])               = []
         StringUtils.stripAll(["abc", "  abc"]) = ["abc", "abc"]
         StringUtils.stripAll(["abc  ", null])  = ["abc", null]
         
        Parameters:
        strs - the array to remove whitespace from, may be null
        Returns:
        the stripped Strings, null if null array input
      • stripAll

        public static String[] stripAll​(String[] strs,
                                        String stripChars)

        Strips any of a set of characters from the start and end of every String in an array.

        Whitespace is defined by Character.isWhitespace(char).

        A new array is returned each time, except for length zero. A null array will return null. An empty array will return itself. A null array entry will be ignored. A null stripChars will strip whitespace as defined by Character.isWhitespace(char).

         StringUtils.stripAll(null, *)                = null
         StringUtils.stripAll([], *)                  = []
         StringUtils.stripAll(["abc", "  abc"], null) = ["abc", "abc"]
         StringUtils.stripAll(["abc  ", null], null)  = ["abc", null]
         StringUtils.stripAll(["abc  ", null], "yz")  = ["abc  ", null]
         StringUtils.stripAll(["yabcz", null], "yz")  = ["abc", null]
         
        Parameters:
        strs - the array to remove characters from, may be null
        stripChars - the characters to remove, null treated as whitespace
        Returns:
        the stripped Strings, null if null array input
      • equals

        public static boolean equals​(String str1,
                                     String str2)

        Compares two Strings, returning true if they are equal.

        nulls are handled without exceptions. Two null references are considered to be equal. The comparison is case sensitive.

         StringUtils.equals(null, null)   = true
         StringUtils.equals(null, "abc")  = false
         StringUtils.equals("abc", null)  = false
         StringUtils.equals("abc", "abc") = true
         StringUtils.equals("abc", "ABC") = false
         
        Parameters:
        str1 - the first String, may be null
        str2 - the second String, may be null
        Returns:
        true if the Strings are equal, case sensitive, or both null
        See Also:
        String.equals(Object)
      • equalsIgnoreCase

        public static boolean equalsIgnoreCase​(String str1,
                                               String str2)

        Compares two Strings, returning true if they are equal ignoring the case.

        nulls are handled without exceptions. Two null references are considered equal. Comparison is case insensitive.

         StringUtils.equalsIgnoreCase(null, null)   = true
         StringUtils.equalsIgnoreCase(null, "abc")  = false
         StringUtils.equalsIgnoreCase("abc", null)  = false
         StringUtils.equalsIgnoreCase("abc", "abc") = true
         StringUtils.equalsIgnoreCase("abc", "ABC") = true
         
        Parameters:
        str1 - the first String, may be null
        str2 - the second String, may be null
        Returns:
        true if the Strings are equal, case insensitive, or both null
        See Also:
        String.equalsIgnoreCase(String)
      • indexOf

        public static int indexOf​(String str,
                                  char searchChar)

        Finds the first index within a String, handling null. This method uses String.indexOf(int).

        A null or empty ("") String will return INDEX_NOT_FOUND (-1).

         StringUtils.indexOf(null, *)         = -1
         StringUtils.indexOf("", *)           = -1
         StringUtils.indexOf("aabaabaa", 'a') = 0
         StringUtils.indexOf("aabaabaa", 'b') = 2
         
        Parameters:
        str - the String to check, may be null
        searchChar - the character to find
        Returns:
        the first index of the search character, -1 if no match or null string input
        Since:
        2.0
      • indexOf

        public static int indexOf​(String str,
                                  char searchChar,
                                  int startPos)

        Finds the first index within a String from a start position, handling null. This method uses String.indexOf(int, int).

        A null or empty ("") String will return (INDEX_NOT_FOUND) -1. A negative start position is treated as zero. A start position greater than the string length returns -1.

         StringUtils.indexOf(null, *, *)          = -1
         StringUtils.indexOf("", *, *)            = -1
         StringUtils.indexOf("aabaabaa", 'b', 0)  = 2
         StringUtils.indexOf("aabaabaa", 'b', 3)  = 5
         StringUtils.indexOf("aabaabaa", 'b', 9)  = -1
         StringUtils.indexOf("aabaabaa", 'b', -1) = 2
         
        Parameters:
        str - the String to check, may be null
        searchChar - the character to find
        startPos - the start position, negative treated as zero
        Returns:
        the first index of the search character, -1 if no match or null string input
        Since:
        2.0
      • indexOf

        public static int indexOf​(String str,
                                  String searchStr)

        Finds the first index within a String, handling null. This method uses String.indexOf(String).

        A null String will return -1.

         StringUtils.indexOf(null, *)          = -1
         StringUtils.indexOf(*, null)          = -1
         StringUtils.indexOf("", "")           = 0
         StringUtils.indexOf("", *)            = -1 (except when * = "")
         StringUtils.indexOf("aabaabaa", "a")  = 0
         StringUtils.indexOf("aabaabaa", "b")  = 2
         StringUtils.indexOf("aabaabaa", "ab") = 1
         StringUtils.indexOf("aabaabaa", "")   = 0
         
        Parameters:
        str - the String to check, may be null
        searchStr - the String to find, may be null
        Returns:
        the first index of the search String, -1 if no match or null string input
        Since:
        2.0
      • ordinalIndexOf

        public static int ordinalIndexOf​(String str,
                                         String searchStr,
                                         int ordinal)

        Finds the n-th index within a String, handling null. This method uses String.indexOf(String).

        A null String will return -1.

         StringUtils.ordinalIndexOf(null, *, *)          = -1
         StringUtils.ordinalIndexOf(*, null, *)          = -1
         StringUtils.ordinalIndexOf("", "", *)           = 0
         StringUtils.ordinalIndexOf("aabaabaa", "a", 1)  = 0
         StringUtils.ordinalIndexOf("aabaabaa", "a", 2)  = 1
         StringUtils.ordinalIndexOf("aabaabaa", "b", 1)  = 2
         StringUtils.ordinalIndexOf("aabaabaa", "b", 2)  = 5
         StringUtils.ordinalIndexOf("aabaabaa", "ab", 1) = 1
         StringUtils.ordinalIndexOf("aabaabaa", "ab", 2) = 4
         StringUtils.ordinalIndexOf("aabaabaa", "", 1)   = 0
         StringUtils.ordinalIndexOf("aabaabaa", "", 2)   = 0
         

        Note that 'head(String str, int n)' may be implemented as:

           str.substring(0, lastOrdinalIndexOf(str, "\n", n))
         
        Parameters:
        str - the String to check, may be null
        searchStr - the String to find, may be null
        ordinal - the n-th searchStr to find
        Returns:
        the n-th index of the search String, -1 (INDEX_NOT_FOUND) if no match or null string input
        Since:
        2.1
      • indexOf

        public static int indexOf​(String str,
                                  String searchStr,
                                  int startPos)

        Finds the first index within a String, handling null. This method uses String.indexOf(String, int).

        A null String will return -1. A negative start position is treated as zero. An empty ("") search String always matches. A start position greater than the string length only matches an empty search String.

         StringUtils.indexOf(null, *, *)          = -1
         StringUtils.indexOf(*, null, *)          = -1
         StringUtils.indexOf("", "", 0)           = 0
         StringUtils.indexOf("", *, 0)            = -1 (except when * = "")
         StringUtils.indexOf("aabaabaa", "a", 0)  = 0
         StringUtils.indexOf("aabaabaa", "b", 0)  = 2
         StringUtils.indexOf("aabaabaa", "ab", 0) = 1
         StringUtils.indexOf("aabaabaa", "b", 3)  = 5
         StringUtils.indexOf("aabaabaa", "b", 9)  = -1
         StringUtils.indexOf("aabaabaa", "b", -1) = 2
         StringUtils.indexOf("aabaabaa", "", 2)   = 2
         StringUtils.indexOf("abc", "", 9)        = 3
         
        Parameters:
        str - the String to check, may be null
        searchStr - the String to find, may be null
        startPos - the start position, negative treated as zero
        Returns:
        the first index of the search String, -1 if no match or null string input
        Since:
        2.0
      • indexOfIgnoreCase

        public static int indexOfIgnoreCase​(String str,
                                            String searchStr)

        Case in-sensitive find of the first index within a String.

        A null String will return -1. A negative start position is treated as zero. An empty ("") search String always matches. A start position greater than the string length only matches an empty search String.

         StringUtils.indexOfIgnoreCase(null, *)          = -1
         StringUtils.indexOfIgnoreCase(*, null)          = -1
         StringUtils.indexOfIgnoreCase("", "")           = 0
         StringUtils.indexOfIgnoreCase("aabaabaa", "a")  = 0
         StringUtils.indexOfIgnoreCase("aabaabaa", "b")  = 2
         StringUtils.indexOfIgnoreCase("aabaabaa", "ab") = 1
         
        Parameters:
        str - the String to check, may be null
        searchStr - the String to find, may be null
        Returns:
        the first index of the search String, -1 if no match or null string input
        Since:
        2.5
      • indexOfIgnoreCase

        public static int indexOfIgnoreCase​(String str,
                                            String searchStr,
                                            int startPos)

        Case in-sensitive find of the first index within a String from the specified position.

        A null String will return -1. A negative start position is treated as zero. An empty ("") search String always matches. A start position greater than the string length only matches an empty search String.

         StringUtils.indexOfIgnoreCase(null, *, *)          = -1
         StringUtils.indexOfIgnoreCase(*, null, *)          = -1
         StringUtils.indexOfIgnoreCase("", "", 0)           = 0
         StringUtils.indexOfIgnoreCase("aabaabaa", "A", 0)  = 0
         StringUtils.indexOfIgnoreCase("aabaabaa", "B", 0)  = 2
         StringUtils.indexOfIgnoreCase("aabaabaa", "AB", 0) = 1
         StringUtils.indexOfIgnoreCase("aabaabaa", "B", 3)  = 5
         StringUtils.indexOfIgnoreCase("aabaabaa", "B", 9)  = -1
         StringUtils.indexOfIgnoreCase("aabaabaa", "B", -1) = 2
         StringUtils.indexOfIgnoreCase("aabaabaa", "", 2)   = 2
         StringUtils.indexOfIgnoreCase("abc", "", 9)        = 3
         
        Parameters:
        str - the String to check, may be null
        searchStr - the String to find, may be null
        startPos - the start position, negative treated as zero
        Returns:
        the first index of the search String, -1 if no match or null string input
        Since:
        2.5
      • lastIndexOf

        public static int lastIndexOf​(String str,
                                      char searchChar)

        Finds the last index within a String, handling null. This method uses String.lastIndexOf(int).

        A null or empty ("") String will return -1.

         StringUtils.lastIndexOf(null, *)         = -1
         StringUtils.lastIndexOf("", *)           = -1
         StringUtils.lastIndexOf("aabaabaa", 'a') = 7
         StringUtils.lastIndexOf("aabaabaa", 'b') = 5
         
        Parameters:
        str - the String to check, may be null
        searchChar - the character to find
        Returns:
        the last index of the search character, -1 if no match or null string input
        Since:
        2.0
      • lastIndexOf

        public static int lastIndexOf​(String str,
                                      char searchChar,
                                      int startPos)

        Finds the last index within a String from a start position, handling null. This method uses String.lastIndexOf(int, int).

        A null or empty ("") String will return -1. A negative start position returns -1. A start position greater than the string length searches the whole string.

         StringUtils.lastIndexOf(null, *, *)          = -1
         StringUtils.lastIndexOf("", *,  *)           = -1
         StringUtils.lastIndexOf("aabaabaa", 'b', 8)  = 5
         StringUtils.lastIndexOf("aabaabaa", 'b', 4)  = 2
         StringUtils.lastIndexOf("aabaabaa", 'b', 0)  = -1
         StringUtils.lastIndexOf("aabaabaa", 'b', 9)  = 5
         StringUtils.lastIndexOf("aabaabaa", 'b', -1) = -1
         StringUtils.lastIndexOf("aabaabaa", 'a', 0)  = 0
         
        Parameters:
        str - the String to check, may be null
        searchChar - the character to find
        startPos - the start position
        Returns:
        the last index of the search character, -1 if no match or null string input
        Since:
        2.0
      • lastIndexOf

        public static int lastIndexOf​(String str,
                                      String searchStr)

        Finds the last index within a String, handling null. This method uses String.lastIndexOf(String).

        A null String will return -1.

         StringUtils.lastIndexOf(null, *)          = -1
         StringUtils.lastIndexOf(*, null)          = -1
         StringUtils.lastIndexOf("", "")           = 0
         StringUtils.lastIndexOf("aabaabaa", "a")  = 7
         StringUtils.lastIndexOf("aabaabaa", "b")  = 5
         StringUtils.lastIndexOf("aabaabaa", "ab") = 4
         StringUtils.lastIndexOf("aabaabaa", "")   = 8
         
        Parameters:
        str - the String to check, may be null
        searchStr - the String to find, may be null
        Returns:
        the last index of the search String, -1 if no match or null string input
        Since:
        2.0
      • lastOrdinalIndexOf

        public static int lastOrdinalIndexOf​(String str,
                                             String searchStr,
                                             int ordinal)

        Finds the n-th last index within a String, handling null. This method uses String.lastIndexOf(String).

        A null String will return -1.

         StringUtils.lastOrdinalIndexOf(null, *, *)          = -1
         StringUtils.lastOrdinalIndexOf(*, null, *)          = -1
         StringUtils.lastOrdinalIndexOf("", "", *)           = 0
         StringUtils.lastOrdinalIndexOf("aabaabaa", "a", 1)  = 7
         StringUtils.lastOrdinalIndexOf("aabaabaa", "a", 2)  = 6
         StringUtils.lastOrdinalIndexOf("aabaabaa", "b", 1)  = 5
         StringUtils.lastOrdinalIndexOf("aabaabaa", "b", 2)  = 2
         StringUtils.lastOrdinalIndexOf("aabaabaa", "ab", 1) = 4
         StringUtils.lastOrdinalIndexOf("aabaabaa", "ab", 2) = 1
         StringUtils.lastOrdinalIndexOf("aabaabaa", "", 1)   = 8
         StringUtils.lastOrdinalIndexOf("aabaabaa", "", 2)   = 8
         

        Note that 'tail(String str, int n)' may be implemented as:

           str.substring(lastOrdinalIndexOf(str, "\n", n) + 1)
         
        Parameters:
        str - the String to check, may be null
        searchStr - the String to find, may be null
        ordinal - the n-th last searchStr to find
        Returns:
        the n-th last index of the search String, -1 (INDEX_NOT_FOUND) if no match or null string input
        Since:
        2.5
      • lastIndexOf

        public static int lastIndexOf​(String str,
                                      String searchStr,
                                      int startPos)

        Finds the first index within a String, handling null. This method uses String.lastIndexOf(String, int).

        A null String will return -1. A negative start position returns -1. An empty ("") search String always matches unless the start position is negative. A start position greater than the string length searches the whole string.

         StringUtils.lastIndexOf(null, *, *)          = -1
         StringUtils.lastIndexOf(*, null, *)          = -1
         StringUtils.lastIndexOf("aabaabaa", "a", 8)  = 7
         StringUtils.lastIndexOf("aabaabaa", "b", 8)  = 5
         StringUtils.lastIndexOf("aabaabaa", "ab", 8) = 4
         StringUtils.lastIndexOf("aabaabaa", "b", 9)  = 5
         StringUtils.lastIndexOf("aabaabaa", "b", -1) = -1
         StringUtils.lastIndexOf("aabaabaa", "a", 0)  = 0
         StringUtils.lastIndexOf("aabaabaa", "b", 0)  = -1
         
        Parameters:
        str - the String to check, may be null
        searchStr - the String to find, may be null
        startPos - the start position, negative treated as zero
        Returns:
        the first index of the search String, -1 if no match or null string input
        Since:
        2.0
      • lastIndexOfIgnoreCase

        public static int lastIndexOfIgnoreCase​(String str,
                                                String searchStr)

        Case in-sensitive find of the last index within a String.

        A null String will return -1. A negative start position returns -1. An empty ("") search String always matches unless the start position is negative. A start position greater than the string length searches the whole string.

         StringUtils.lastIndexOfIgnoreCase(null, *)          = -1
         StringUtils.lastIndexOfIgnoreCase(*, null)          = -1
         StringUtils.lastIndexOfIgnoreCase("aabaabaa", "A")  = 7
         StringUtils.lastIndexOfIgnoreCase("aabaabaa", "B")  = 5
         StringUtils.lastIndexOfIgnoreCase("aabaabaa", "AB") = 4
         
        Parameters:
        str - the String to check, may be null
        searchStr - the String to find, may be null
        Returns:
        the first index of the search String, -1 if no match or null string input
        Since:
        2.5
      • lastIndexOfIgnoreCase

        public static int lastIndexOfIgnoreCase​(String str,
                                                String searchStr,
                                                int startPos)

        Case in-sensitive find of the last index within a String from the specified position.

        A null String will return -1. A negative start position returns -1. An empty ("") search String always matches unless the start position is negative. A start position greater than the string length searches the whole string.

         StringUtils.lastIndexOfIgnoreCase(null, *, *)          = -1
         StringUtils.lastIndexOfIgnoreCase(*, null, *)          = -1
         StringUtils.lastIndexOfIgnoreCase("aabaabaa", "A", 8)  = 7
         StringUtils.lastIndexOfIgnoreCase("aabaabaa", "B", 8)  = 5
         StringUtils.lastIndexOfIgnoreCase("aabaabaa", "AB", 8) = 4
         StringUtils.lastIndexOfIgnoreCase("aabaabaa", "B", 9)  = 5
         StringUtils.lastIndexOfIgnoreCase("aabaabaa", "B", -1) = -1
         StringUtils.lastIndexOfIgnoreCase("aabaabaa", "A", 0)  = 0
         StringUtils.lastIndexOfIgnoreCase("aabaabaa", "B", 0)  = -1
         
        Parameters:
        str - the String to check, may be null
        searchStr - the String to find, may be null
        startPos - the start position
        Returns:
        the first index of the search String, -1 if no match or null string input
        Since:
        2.5
      • contains

        public static boolean contains​(String str,
                                       char searchChar)

        Checks if String contains a search character, handling null. This method uses String.indexOf(int).

        A null or empty ("") String will return false.

         StringUtils.contains(null, *)    = false
         StringUtils.contains("", *)      = false
         StringUtils.contains("abc", 'a') = true
         StringUtils.contains("abc", 'z') = false
         
        Parameters:
        str - the String to check, may be null
        searchChar - the character to find
        Returns:
        true if the String contains the search character, false if not or null string input
        Since:
        2.0
      • contains

        public static boolean contains​(String str,
                                       String searchStr)

        Checks if String contains a search String, handling null. This method uses String.indexOf(String).

        A null String will return false.

         StringUtils.contains(null, *)     = false
         StringUtils.contains(*, null)     = false
         StringUtils.contains("", "")      = true
         StringUtils.contains("abc", "")   = true
         StringUtils.contains("abc", "a")  = true
         StringUtils.contains("abc", "z")  = false
         
        Parameters:
        str - the String to check, may be null
        searchStr - the String to find, may be null
        Returns:
        true if the String contains the search String, false if not or null string input
        Since:
        2.0
      • containsIgnoreCase

        public static boolean containsIgnoreCase​(String str,
                                                 String searchStr)

        Checks if String contains a search String irrespective of case, handling null. Case-insensitivity is defined as by String.equalsIgnoreCase(String).

        A null String will return false.

         StringUtils.contains(null, *) = false
         StringUtils.contains(*, null) = false
         StringUtils.contains("", "") = true
         StringUtils.contains("abc", "") = true
         StringUtils.contains("abc", "a") = true
         StringUtils.contains("abc", "z") = false
         StringUtils.contains("abc", "A") = true
         StringUtils.contains("abc", "Z") = false
         
        Parameters:
        str - the String to check, may be null
        searchStr - the String to find, may be null
        Returns:
        true if the String contains the search String irrespective of case or false if not or null string input
      • indexOfAny

        public static int indexOfAny​(String str,
                                     char[] searchChars)

        Search a String to find the first index of any character in the given set of characters.

        A null String will return -1. A null or zero length search array will return -1.

         StringUtils.indexOfAny(null, *)                = -1
         StringUtils.indexOfAny("", *)                  = -1
         StringUtils.indexOfAny(*, null)                = -1
         StringUtils.indexOfAny(*, [])                  = -1
         StringUtils.indexOfAny("zzabyycdxx",['z','a']) = 0
         StringUtils.indexOfAny("zzabyycdxx",['b','y']) = 3
         StringUtils.indexOfAny("aba", ['z'])           = -1
         
        Parameters:
        str - the String to check, may be null
        searchChars - the chars to search for, may be null
        Returns:
        the index of any of the chars, -1 if no match or null input
        Since:
        2.0
      • indexOfAny

        public static int indexOfAny​(String str,
                                     String searchChars)

        Search a String to find the first index of any character in the given set of characters.

        A null String will return -1. A null search string will return -1.

         StringUtils.indexOfAny(null, *)            = -1
         StringUtils.indexOfAny("", *)              = -1
         StringUtils.indexOfAny(*, null)            = -1
         StringUtils.indexOfAny(*, "")              = -1
         StringUtils.indexOfAny("zzabyycdxx", "za") = 0
         StringUtils.indexOfAny("zzabyycdxx", "by") = 3
         StringUtils.indexOfAny("aba","z")          = -1
         
        Parameters:
        str - the String to check, may be null
        searchChars - the chars to search for, may be null
        Returns:
        the index of any of the chars, -1 if no match or null input
        Since:
        2.0
      • containsAny

        public static boolean containsAny​(String str,
                                          char[] searchChars)

        Checks if the String contains any character in the given set of characters.

        A null String will return false. A null or zero length search array will return false.

         StringUtils.containsAny(null, *)                = false
         StringUtils.containsAny("", *)                  = false
         StringUtils.containsAny(*, null)                = false
         StringUtils.containsAny(*, [])                  = false
         StringUtils.containsAny("zzabyycdxx",['z','a']) = true
         StringUtils.containsAny("zzabyycdxx",['b','y']) = true
         StringUtils.containsAny("aba", ['z'])           = false
         
        Parameters:
        str - the String to check, may be null
        searchChars - the chars to search for, may be null
        Returns:
        the true if any of the chars are found, false if no match or null input
        Since:
        2.4
      • containsAny

        public static boolean containsAny​(String str,
                                          String searchChars)

        Checks if the String contains any character in the given set of characters.

        A null String will return false. A null search string will return false.

         StringUtils.containsAny(null, *)            = false
         StringUtils.containsAny("", *)              = false
         StringUtils.containsAny(*, null)            = false
         StringUtils.containsAny(*, "")              = false
         StringUtils.containsAny("zzabyycdxx", "za") = true
         StringUtils.containsAny("zzabyycdxx", "by") = true
         StringUtils.containsAny("aba","z")          = false
         
        Parameters:
        str - the String to check, may be null
        searchChars - the chars to search for, may be null
        Returns:
        the true if any of the chars are found, false if no match or null input
        Since:
        2.4
      • indexOfAnyBut

        public static int indexOfAnyBut​(String str,
                                        char[] searchChars)

        Search a String to find the first index of any character not in the given set of characters.

        A null String will return -1. A null or zero length search array will return -1.

         StringUtils.indexOfAnyBut(null, *)                              = -1
         StringUtils.indexOfAnyBut("", *)                                = -1
         StringUtils.indexOfAnyBut(*, null)                              = -1
         StringUtils.indexOfAnyBut(*, [])                                = -1
         StringUtils.indexOfAnyBut("zzabyycdxx", new char[] {'z', 'a'} ) = 3
         StringUtils.indexOfAnyBut("aba", new char[] {'z'} )             = 0
         StringUtils.indexOfAnyBut("aba", new char[] {'a', 'b'} )        = -1
         
        Parameters:
        str - the String to check, may be null
        searchChars - the chars to search for, may be null
        Returns:
        the index of any of the chars, -1 if no match or null input
        Since:
        2.0
      • indexOfAnyBut

        public static int indexOfAnyBut​(String str,
                                        String searchChars)

        Search a String to find the first index of any character not in the given set of characters.

        A null String will return -1. A null or empty search string will return -1.

         StringUtils.indexOfAnyBut(null, *)            = -1
         StringUtils.indexOfAnyBut("", *)              = -1
         StringUtils.indexOfAnyBut(*, null)            = -1
         StringUtils.indexOfAnyBut(*, "")              = -1
         StringUtils.indexOfAnyBut("zzabyycdxx", "za") = 3
         StringUtils.indexOfAnyBut("zzabyycdxx", "")   = -1
         StringUtils.indexOfAnyBut("aba","ab")         = -1
         
        Parameters:
        str - the String to check, may be null
        searchChars - the chars to search for, may be null
        Returns:
        the index of any of the chars, -1 if no match or null input
        Since:
        2.0
      • containsOnly

        public static boolean containsOnly​(String str,
                                           char[] valid)

        Checks if the String contains only certain characters.

        A null String will return false. A null valid character array will return false. An empty String (length()=0) always returns true.

         StringUtils.containsOnly(null, *)       = false
         StringUtils.containsOnly(*, null)       = false
         StringUtils.containsOnly("", *)         = true
         StringUtils.containsOnly("ab", '')      = false
         StringUtils.containsOnly("abab", 'abc') = true
         StringUtils.containsOnly("ab1", 'abc')  = false
         StringUtils.containsOnly("abz", 'abc')  = false
         
        Parameters:
        str - the String to check, may be null
        valid - an array of valid chars, may be null
        Returns:
        true if it only contains valid chars and is non-null
      • containsOnly

        public static boolean containsOnly​(String str,
                                           String validChars)

        Checks if the String contains only certain characters.

        A null String will return false. A null valid character String will return false. An empty String (length()=0) always returns true.

         StringUtils.containsOnly(null, *)       = false
         StringUtils.containsOnly(*, null)       = false
         StringUtils.containsOnly("", *)         = true
         StringUtils.containsOnly("ab", "")      = false
         StringUtils.containsOnly("abab", "abc") = true
         StringUtils.containsOnly("ab1", "abc")  = false
         StringUtils.containsOnly("abz", "abc")  = false
         
        Parameters:
        str - the String to check, may be null
        validChars - a String of valid chars, may be null
        Returns:
        true if it only contains valid chars and is non-null
        Since:
        2.0
      • containsNone

        public static boolean containsNone​(String str,
                                           char[] searchChars)

        Checks that the String does not contain certain characters.

        A null String will return true. A null invalid character array will return true. An empty String (length()=0) always returns true.

         StringUtils.containsNone(null, *)       = true
         StringUtils.containsNone(*, null)       = true
         StringUtils.containsNone("", *)         = true
         StringUtils.containsNone("ab", '')      = true
         StringUtils.containsNone("abab", 'xyz') = true
         StringUtils.containsNone("ab1", 'xyz')  = true
         StringUtils.containsNone("abz", 'xyz')  = false
         
        Parameters:
        str - the String to check, may be null
        searchChars - an array of invalid chars, may be null
        Returns:
        true if it contains none of the invalid chars, or is null
        Since:
        2.0
      • containsNone

        public static boolean containsNone​(String str,
                                           String invalidChars)

        Checks that the String does not contain certain characters.

        A null String will return true. A null invalid character array will return true. An empty String ("") always returns true.

         StringUtils.containsNone(null, *)       = true
         StringUtils.containsNone(*, null)       = true
         StringUtils.containsNone("", *)         = true
         StringUtils.containsNone("ab", "")      = true
         StringUtils.containsNone("abab", "xyz") = true
         StringUtils.containsNone("ab1", "xyz")  = true
         StringUtils.containsNone("abz", "xyz")  = false
         
        Parameters:
        str - the String to check, may be null
        invalidChars - a String of invalid chars, may be null
        Returns:
        true if it contains none of the invalid chars, or is null
        Since:
        2.0
      • indexOfAny

        public static int indexOfAny​(String str,
                                     String[] searchStrs)

        Find the first index of any of a set of potential substrings.

        A null String will return -1. A null or zero length search array will return -1. A null search array entry will be ignored, but a search array containing "" will return 0 if str is not null. This method uses String.indexOf(String).

         StringUtils.indexOfAny(null, *)                     = -1
         StringUtils.indexOfAny(*, null)                     = -1
         StringUtils.indexOfAny(*, [])                       = -1
         StringUtils.indexOfAny("zzabyycdxx", ["ab","cd"])   = 2
         StringUtils.indexOfAny("zzabyycdxx", ["cd","ab"])   = 2
         StringUtils.indexOfAny("zzabyycdxx", ["mn","op"])   = -1
         StringUtils.indexOfAny("zzabyycdxx", ["zab","aby"]) = 1
         StringUtils.indexOfAny("zzabyycdxx", [""])          = 0
         StringUtils.indexOfAny("", [""])                    = 0
         StringUtils.indexOfAny("", ["a"])                   = -1
         
        Parameters:
        str - the String to check, may be null
        searchStrs - the Strings to search for, may be null
        Returns:
        the first index of any of the searchStrs in str, -1 if no match
      • lastIndexOfAny

        public static int lastIndexOfAny​(String str,
                                         String[] searchStrs)

        Find the latest index of any of a set of potential substrings.

        A null String will return -1. A null search array will return -1. A null or zero length search array entry will be ignored, but a search array containing "" will return the length of str if str is not null. This method uses String.indexOf(String)

         StringUtils.lastIndexOfAny(null, *)                   = -1
         StringUtils.lastIndexOfAny(*, null)                   = -1
         StringUtils.lastIndexOfAny(*, [])                     = -1
         StringUtils.lastIndexOfAny(*, [null])                 = -1
         StringUtils.lastIndexOfAny("zzabyycdxx", ["ab","cd"]) = 6
         StringUtils.lastIndexOfAny("zzabyycdxx", ["cd","ab"]) = 6
         StringUtils.lastIndexOfAny("zzabyycdxx", ["mn","op"]) = -1
         StringUtils.lastIndexOfAny("zzabyycdxx", ["mn","op"]) = -1
         StringUtils.lastIndexOfAny("zzabyycdxx", ["mn",""])   = 10
         
        Parameters:
        str - the String to check, may be null
        searchStrs - the Strings to search for, may be null
        Returns:
        the last index of any of the Strings, -1 if no match
      • substring

        public static String substring​(String str,
                                       int start)

        Gets a substring from the specified String avoiding exceptions.

        A negative start position can be used to start n characters from the end of the String.

        A null String will return null. An empty ("") String will return "".

         StringUtils.substring(null, *)   = null
         StringUtils.substring("", *)     = ""
         StringUtils.substring("abc", 0)  = "abc"
         StringUtils.substring("abc", 2)  = "c"
         StringUtils.substring("abc", 4)  = ""
         StringUtils.substring("abc", -2) = "bc"
         StringUtils.substring("abc", -4) = "abc"
         
        Parameters:
        str - the String to get the substring from, may be null
        start - the position to start from, negative means count back from the end of the String by this many characters
        Returns:
        substring from start position, null if null String input
      • substring

        public static String substring​(String str,
                                       int start,
                                       int end)

        Gets a substring from the specified String avoiding exceptions.

        A negative start position can be used to start/end n characters from the end of the String.

        The returned substring starts with the character in the start position and ends before the end position. All position counting is zero-based -- i.e., to start at the beginning of the string use start = 0. Negative start and end positions can be used to specify offsets relative to the end of the String.

        If start is not strictly to the left of end, "" is returned.

         StringUtils.substring(null, *, *)    = null
         StringUtils.substring("", * ,  *)    = "";
         StringUtils.substring("abc", 0, 2)   = "ab"
         StringUtils.substring("abc", 2, 0)   = ""
         StringUtils.substring("abc", 2, 4)   = "c"
         StringUtils.substring("abc", 4, 6)   = ""
         StringUtils.substring("abc", 2, 2)   = ""
         StringUtils.substring("abc", -2, -1) = "b"
         StringUtils.substring("abc", -4, 2)  = "ab"
         
        Parameters:
        str - the String to get the substring from, may be null
        start - the position to start from, negative means count back from the end of the String by this many characters
        end - the position to end at (exclusive), negative means count back from the end of the String by this many characters
        Returns:
        substring from start position to end positon, null if null String input
      • left

        public static String left​(String str,
                                  int len)

        Gets the leftmost len characters of a String.

        If len characters are not available, or the String is null, the String will be returned without an exception. An empty String is returned if len is negative.

         StringUtils.left(null, *)    = null
         StringUtils.left(*, -ve)     = ""
         StringUtils.left("", *)      = ""
         StringUtils.left("abc", 0)   = ""
         StringUtils.left("abc", 2)   = "ab"
         StringUtils.left("abc", 4)   = "abc"
         
        Parameters:
        str - the String to get the leftmost characters from, may be null
        len - the length of the required String
        Returns:
        the leftmost characters, null if null String input
      • right

        public static String right​(String str,
                                   int len)

        Gets the rightmost len characters of a String.

        If len characters are not available, or the String is null, the String will be returned without an an exception. An empty String is returned if len is negative.

         StringUtils.right(null, *)    = null
         StringUtils.right(*, -ve)     = ""
         StringUtils.right("", *)      = ""
         StringUtils.right("abc", 0)   = ""
         StringUtils.right("abc", 2)   = "bc"
         StringUtils.right("abc", 4)   = "abc"
         
        Parameters:
        str - the String to get the rightmost characters from, may be null
        len - the length of the required String
        Returns:
        the rightmost characters, null if null String input
      • mid

        public static String mid​(String str,
                                 int pos,
                                 int len)

        Gets len characters from the middle of a String.

        If len characters are not available, the remainder of the String will be returned without an exception. If the String is null, null will be returned. An empty String is returned if len is negative or exceeds the length of str.

         StringUtils.mid(null, *, *)    = null
         StringUtils.mid(*, *, -ve)     = ""
         StringUtils.mid("", 0, *)      = ""
         StringUtils.mid("abc", 0, 2)   = "ab"
         StringUtils.mid("abc", 0, 4)   = "abc"
         StringUtils.mid("abc", 2, 4)   = "c"
         StringUtils.mid("abc", 4, 2)   = ""
         StringUtils.mid("abc", -2, 2)  = "ab"
         
        Parameters:
        str - the String to get the characters from, may be null
        pos - the position to start from, negative treated as zero
        len - the length of the required String
        Returns:
        the middle characters, null if null String input
      • substringBefore

        public static String substringBefore​(String str,
                                             String separator)

        Gets the substring before the first occurrence of a separator. The separator is not returned.

        A null string input will return null. An empty ("") string input will return the empty string. A null separator will return the input string.

        If nothing is found, the string input is returned.

         StringUtils.substringBefore(null, *)      = null
         StringUtils.substringBefore("", *)        = ""
         StringUtils.substringBefore("abc", "a")   = ""
         StringUtils.substringBefore("abcba", "b") = "a"
         StringUtils.substringBefore("abc", "c")   = "ab"
         StringUtils.substringBefore("abc", "d")   = "abc"
         StringUtils.substringBefore("abc", "")    = ""
         StringUtils.substringBefore("abc", null)  = "abc"
         
        Parameters:
        str - the String to get a substring from, may be null
        separator - the String to search for, may be null
        Returns:
        the substring before the first occurrence of the separator, null if null String input
        Since:
        2.0
      • substringAfter

        public static String substringAfter​(String str,
                                            String separator)

        Gets the substring after the first occurrence of a separator. The separator is not returned.

        A null string input will return null. An empty ("") string input will return the empty string. A null separator will return the empty string if the input string is not null.

        If nothing is found, the empty string is returned.

         StringUtils.substringAfter(null, *)      = null
         StringUtils.substringAfter("", *)        = ""
         StringUtils.substringAfter(*, null)      = ""
         StringUtils.substringAfter("abc", "a")   = "bc"
         StringUtils.substringAfter("abcba", "b") = "cba"
         StringUtils.substringAfter("abc", "c")   = ""
         StringUtils.substringAfter("abc", "d")   = ""
         StringUtils.substringAfter("abc", "")    = "abc"
         
        Parameters:
        str - the String to get a substring from, may be null
        separator - the String to search for, may be null
        Returns:
        the substring after the first occurrence of the separator, null if null String input
        Since:
        2.0
      • substringBeforeLast

        public static String substringBeforeLast​(String str,
                                                 String separator)

        Gets the substring before the last occurrence of a separator. The separator is not returned.

        A null string input will return null. An empty ("") string input will return the empty string. An empty or null separator will return the input string.

        If nothing is found, the string input is returned.

         StringUtils.substringBeforeLast(null, *)      = null
         StringUtils.substringBeforeLast("", *)        = ""
         StringUtils.substringBeforeLast("abcba", "b") = "abc"
         StringUtils.substringBeforeLast("abc", "c")   = "ab"
         StringUtils.substringBeforeLast("a", "a")     = ""
         StringUtils.substringBeforeLast("a", "z")     = "a"
         StringUtils.substringBeforeLast("a", null)    = "a"
         StringUtils.substringBeforeLast("a", "")      = "a"
         
        Parameters:
        str - the String to get a substring from, may be null
        separator - the String to search for, may be null
        Returns:
        the substring before the last occurrence of the separator, null if null String input
        Since:
        2.0
      • substringAfterLast

        public static String substringAfterLast​(String str,
                                                String separator)

        Gets the substring after the last occurrence of a separator. The separator is not returned.

        A null string input will return null. An empty ("") string input will return the empty string. An empty or null separator will return the empty string if the input string is not null.

        If nothing is found, the empty string is returned.

         StringUtils.substringAfterLast(null, *)      = null
         StringUtils.substringAfterLast("", *)        = ""
         StringUtils.substringAfterLast(*, "")        = ""
         StringUtils.substringAfterLast(*, null)      = ""
         StringUtils.substringAfterLast("abc", "a")   = "bc"
         StringUtils.substringAfterLast("abcba", "b") = "a"
         StringUtils.substringAfterLast("abc", "c")   = ""
         StringUtils.substringAfterLast("a", "a")     = ""
         StringUtils.substringAfterLast("a", "z")     = ""
         
        Parameters:
        str - the String to get a substring from, may be null
        separator - the String to search for, may be null
        Returns:
        the substring after the last occurrence of the separator, null if null String input
        Since:
        2.0
      • substringBetween

        public static String substringBetween​(String str,
                                              String tag)

        Gets the String that is nested in between two instances of the same String.

        A null input String returns null. A null tag returns null.

         StringUtils.substringBetween(null, *)            = null
         StringUtils.substringBetween("", "")             = ""
         StringUtils.substringBetween("", "tag")          = null
         StringUtils.substringBetween("tagabctag", null)  = null
         StringUtils.substringBetween("tagabctag", "")    = ""
         StringUtils.substringBetween("tagabctag", "tag") = "abc"
         
        Parameters:
        str - the String containing the substring, may be null
        tag - the String before and after the substring, may be null
        Returns:
        the substring, null if no match
        Since:
        2.0
      • substringBetween

        public static String substringBetween​(String str,
                                              String open,
                                              String close)

        Gets the String that is nested in between two Strings. Only the first match is returned.

        A null input String returns null. A null open/close returns null (no match). An empty ("") open and close returns an empty string.

         StringUtils.substringBetween("wx[b]yz", "[", "]") = "b"
         StringUtils.substringBetween(null, *, *)          = null
         StringUtils.substringBetween(*, null, *)          = null
         StringUtils.substringBetween(*, *, null)          = null
         StringUtils.substringBetween("", "", "")          = ""
         StringUtils.substringBetween("", "", "]")         = null
         StringUtils.substringBetween("", "[", "]")        = null
         StringUtils.substringBetween("yabcz", "", "")     = ""
         StringUtils.substringBetween("yabcz", "y", "z")   = "abc"
         StringUtils.substringBetween("yabczyabcz", "y", "z")   = "abc"
         
        Parameters:
        str - the String containing the substring, may be null
        open - the String before the substring, may be null
        close - the String after the substring, may be null
        Returns:
        the substring, null if no match
        Since:
        2.0
      • substringsBetween

        public static String[] substringsBetween​(String str,
                                                 String open,
                                                 String close)

        Searches a String for substrings delimited by a start and end tag, returning all matching substrings in an array.

        A null input String returns null. A null open/close returns null (no match). An empty ("") open/close returns null (no match).

         StringUtils.substringsBetween("[a][b][c]", "[", "]") = ["a","b","c"]
         StringUtils.substringsBetween(null, *, *)            = null
         StringUtils.substringsBetween(*, null, *)            = null
         StringUtils.substringsBetween(*, *, null)            = null
         StringUtils.substringsBetween("", "[", "]")          = []
         
        Parameters:
        str - the String containing the substrings, null returns null, empty returns empty
        open - the String identifying the start of the substring, empty returns null
        close - the String identifying the end of the substring, empty returns null
        Returns:
        a String Array of substrings, or null if no match
        Since:
        2.3
      • getNestedString

        public static String getNestedString​(String str,
                                             String tag)
        Deprecated.
        Use the better named substringBetween(String, String). Method will be removed in Commons Lang 3.0.

        Gets the String that is nested in between two instances of the same String.

        A null input String returns null. A null tag returns null.

         StringUtils.getNestedString(null, *)            = null
         StringUtils.getNestedString("", "")             = ""
         StringUtils.getNestedString("", "tag")          = null
         StringUtils.getNestedString("tagabctag", null)  = null
         StringUtils.getNestedString("tagabctag", "")    = ""
         StringUtils.getNestedString("tagabctag", "tag") = "abc"
         
        Parameters:
        str - the String containing nested-string, may be null
        tag - the String before and after nested-string, may be null
        Returns:
        the nested String, null if no match
      • getNestedString

        public static String getNestedString​(String str,
                                             String open,
                                             String close)
        Deprecated.
        Use the better named substringBetween(String, String, String). Method will be removed in Commons Lang 3.0.

        Gets the String that is nested in between two Strings. Only the first match is returned.

        A null input String returns null. A null open/close returns null (no match). An empty ("") open/close returns an empty string.

         StringUtils.getNestedString(null, *, *)          = null
         StringUtils.getNestedString("", "", "")          = ""
         StringUtils.getNestedString("", "", "tag")       = null
         StringUtils.getNestedString("", "tag", "tag")    = null
         StringUtils.getNestedString("yabcz", null, null) = null
         StringUtils.getNestedString("yabcz", "", "")     = ""
         StringUtils.getNestedString("yabcz", "y", "z")   = "abc"
         StringUtils.getNestedString("yabczyabcz", "y", "z")   = "abc"
         
        Parameters:
        str - the String containing nested-string, may be null
        open - the String before nested-string, may be null
        close - the String after nested-string, may be null
        Returns:
        the nested String, null if no match
      • split

        public static String[] split​(String str)

        Splits the provided text into an array, using whitespace as the separator. Whitespace is defined by Character.isWhitespace(char).

        The separator is not included in the returned String array. Adjacent separators are treated as one separator. For more control over the split use the StrTokenizer class.

        A null input String returns null.

         StringUtils.split(null)       = null
         StringUtils.split("")         = []
         StringUtils.split("abc def")  = ["abc", "def"]
         StringUtils.split("abc  def") = ["abc", "def"]
         StringUtils.split(" abc ")    = ["abc"]
         
        Parameters:
        str - the String to parse, may be null
        Returns:
        an array of parsed Strings, null if null String input
      • split

        public static String[] split​(String str,
                                     char separatorChar)

        Splits the provided text into an array, separator specified. This is an alternative to using StringTokenizer.

        The separator is not included in the returned String array. Adjacent separators are treated as one separator. For more control over the split use the StrTokenizer class.

        A null input String returns null.

         StringUtils.split(null, *)         = null
         StringUtils.split("", *)           = []
         StringUtils.split("a.b.c", '.')    = ["a", "b", "c"]
         StringUtils.split("a..b.c", '.')   = ["a", "b", "c"]
         StringUtils.split("a:b:c", '.')    = ["a:b:c"]
         StringUtils.split("a b c", ' ')    = ["a", "b", "c"]
         
        Parameters:
        str - the String to parse, may be null
        separatorChar - the character used as the delimiter
        Returns:
        an array of parsed Strings, null if null String input
        Since:
        2.0
      • split

        public static String[] split​(String str,
                                     String separatorChars)

        Splits the provided text into an array, separators specified. This is an alternative to using StringTokenizer.

        The separator is not included in the returned String array. Adjacent separators are treated as one separator. For more control over the split use the StrTokenizer class.

        A null input String returns null. A null separatorChars splits on whitespace.

         StringUtils.split(null, *)         = null
         StringUtils.split("", *)           = []
         StringUtils.split("abc def", null) = ["abc", "def"]
         StringUtils.split("abc def", " ")  = ["abc", "def"]
         StringUtils.split("abc  def", " ") = ["abc", "def"]
         StringUtils.split("ab:cd:ef", ":") = ["ab", "cd", "ef"]
         
        Parameters:
        str - the String to parse, may be null
        separatorChars - the characters used as the delimiters, null splits on whitespace
        Returns:
        an array of parsed Strings, null if null String input
      • split

        public static String[] split​(String str,
                                     String separatorChars,
                                     int max)

        Splits the provided text into an array with a maximum length, separators specified.

        The separator is not included in the returned String array. Adjacent separators are treated as one separator.

        A null input String returns null. A null separatorChars splits on whitespace.

        If more than max delimited substrings are found, the last returned string includes all characters after the first max - 1 returned strings (including separator characters).

         StringUtils.split(null, *, *)            = null
         StringUtils.split("", *, *)              = []
         StringUtils.split("ab de fg", null, 0)   = ["ab", "cd", "ef"]
         StringUtils.split("ab   de fg", null, 0) = ["ab", "cd", "ef"]
         StringUtils.split("ab:cd:ef", ":", 0)    = ["ab", "cd", "ef"]
         StringUtils.split("ab:cd:ef", ":", 2)    = ["ab", "cd:ef"]
         
        Parameters:
        str - the String to parse, may be null
        separatorChars - the characters used as the delimiters, null splits on whitespace
        max - the maximum number of elements to include in the array. A zero or negative value implies no limit
        Returns:
        an array of parsed Strings, null if null String input
      • splitByWholeSeparator

        public static String[] splitByWholeSeparator​(String str,
                                                     String separator)

        Splits the provided text into an array, separator string specified.

        The separator(s) will not be included in the returned String array. Adjacent separators are treated as one separator.

        A null input String returns null. A null separator splits on whitespace.

         StringUtils.splitByWholeSeparator(null, *)               = null
         StringUtils.splitByWholeSeparator("", *)                 = []
         StringUtils.splitByWholeSeparator("ab de fg", null)      = ["ab", "de", "fg"]
         StringUtils.splitByWholeSeparator("ab   de fg", null)    = ["ab", "de", "fg"]
         StringUtils.splitByWholeSeparator("ab:cd:ef", ":")       = ["ab", "cd", "ef"]
         StringUtils.splitByWholeSeparator("ab-!-cd-!-ef", "-!-") = ["ab", "cd", "ef"]
         
        Parameters:
        str - the String to parse, may be null
        separator - String containing the String to be used as a delimiter, null splits on whitespace
        Returns:
        an array of parsed Strings, null if null String was input
      • splitByWholeSeparator

        public static String[] splitByWholeSeparator​(String str,
                                                     String separator,
                                                     int max)

        Splits the provided text into an array, separator string specified. Returns a maximum of max substrings.

        The separator(s) will not be included in the returned String array. Adjacent separators are treated as one separator.

        A null input String returns null. A null separator splits on whitespace.

         StringUtils.splitByWholeSeparator(null, *, *)               = null
         StringUtils.splitByWholeSeparator("", *, *)                 = []
         StringUtils.splitByWholeSeparator("ab de fg", null, 0)      = ["ab", "de", "fg"]
         StringUtils.splitByWholeSeparator("ab   de fg", null, 0)    = ["ab", "de", "fg"]
         StringUtils.splitByWholeSeparator("ab:cd:ef", ":", 2)       = ["ab", "cd:ef"]
         StringUtils.splitByWholeSeparator("ab-!-cd-!-ef", "-!-", 5) = ["ab", "cd", "ef"]
         StringUtils.splitByWholeSeparator("ab-!-cd-!-ef", "-!-", 2) = ["ab", "cd-!-ef"]
         
        Parameters:
        str - the String to parse, may be null
        separator - String containing the String to be used as a delimiter, null splits on whitespace
        max - the maximum number of elements to include in the returned array. A zero or negative value implies no limit.
        Returns:
        an array of parsed Strings, null if null String was input
      • splitByWholeSeparatorPreserveAllTokens

        public static String[] splitByWholeSeparatorPreserveAllTokens​(String str,
                                                                      String separator)

        Splits the provided text into an array, separator string specified.

        The separator is not included in the returned String array. Adjacent separators are treated as separators for empty tokens. For more control over the split use the StrTokenizer class.

        A null input String returns null. A null separator splits on whitespace.

         StringUtils.splitByWholeSeparatorPreserveAllTokens(null, *)               = null
         StringUtils.splitByWholeSeparatorPreserveAllTokens("", *)                 = []
         StringUtils.splitByWholeSeparatorPreserveAllTokens("ab de fg", null)      = ["ab", "de", "fg"]
         StringUtils.splitByWholeSeparatorPreserveAllTokens("ab   de fg", null)    = ["ab", "", "", "de", "fg"]
         StringUtils.splitByWholeSeparatorPreserveAllTokens("ab:cd:ef", ":")       = ["ab", "cd", "ef"]
         StringUtils.splitByWholeSeparatorPreserveAllTokens("ab-!-cd-!-ef", "-!-") = ["ab", "cd", "ef"]
         
        Parameters:
        str - the String to parse, may be null
        separator - String containing the String to be used as a delimiter, null splits on whitespace
        Returns:
        an array of parsed Strings, null if null String was input
        Since:
        2.4
      • splitByWholeSeparatorPreserveAllTokens

        public static String[] splitByWholeSeparatorPreserveAllTokens​(String str,
                                                                      String separator,
                                                                      int max)

        Splits the provided text into an array, separator string specified. Returns a maximum of max substrings.

        The separator is not included in the returned String array. Adjacent separators are treated as separators for empty tokens. For more control over the split use the StrTokenizer class.

        A null input String returns null. A null separator splits on whitespace.

         StringUtils.splitByWholeSeparatorPreserveAllTokens(null, *, *)               = null
         StringUtils.splitByWholeSeparatorPreserveAllTokens("", *, *)                 = []
         StringUtils.splitByWholeSeparatorPreserveAllTokens("ab de fg", null, 0)      = ["ab", "de", "fg"]
         StringUtils.splitByWholeSeparatorPreserveAllTokens("ab   de fg", null, 0)    = ["ab", "", "", "de", "fg"]
         StringUtils.splitByWholeSeparatorPreserveAllTokens("ab:cd:ef", ":", 2)       = ["ab", "cd:ef"]
         StringUtils.splitByWholeSeparatorPreserveAllTokens("ab-!-cd-!-ef", "-!-", 5) = ["ab", "cd", "ef"]
         StringUtils.splitByWholeSeparatorPreserveAllTokens("ab-!-cd-!-ef", "-!-", 2) = ["ab", "cd-!-ef"]
         
        Parameters:
        str - the String to parse, may be null
        separator - String containing the String to be used as a delimiter, null splits on whitespace
        max - the maximum number of elements to include in the returned array. A zero or negative value implies no limit.
        Returns:
        an array of parsed Strings, null if null String was input
        Since:
        2.4
      • splitPreserveAllTokens

        public static String[] splitPreserveAllTokens​(String str)

        Splits the provided text into an array, using whitespace as the separator, preserving all tokens, including empty tokens created by adjacent separators. This is an alternative to using StringTokenizer. Whitespace is defined by Character.isWhitespace(char).

        The separator is not included in the returned String array. Adjacent separators are treated as separators for empty tokens. For more control over the split use the StrTokenizer class.

        A null input String returns null.

         StringUtils.splitPreserveAllTokens(null)       = null
         StringUtils.splitPreserveAllTokens("")         = []
         StringUtils.splitPreserveAllTokens("abc def")  = ["abc", "def"]
         StringUtils.splitPreserveAllTokens("abc  def") = ["abc", "", "def"]
         StringUtils.splitPreserveAllTokens(" abc ")    = ["", "abc", ""]
         
        Parameters:
        str - the String to parse, may be null
        Returns:
        an array of parsed Strings, null if null String input
        Since:
        2.1
      • splitPreserveAllTokens

        public static String[] splitPreserveAllTokens​(String str,
                                                      char separatorChar)

        Splits the provided text into an array, separator specified, preserving all tokens, including empty tokens created by adjacent separators. This is an alternative to using StringTokenizer.

        The separator is not included in the returned String array. Adjacent separators are treated as separators for empty tokens. For more control over the split use the StrTokenizer class.

        A null input String returns null.

         StringUtils.splitPreserveAllTokens(null, *)         = null
         StringUtils.splitPreserveAllTokens("", *)           = []
         StringUtils.splitPreserveAllTokens("a.b.c", '.')    = ["a", "b", "c"]
         StringUtils.splitPreserveAllTokens("a..b.c", '.')   = ["a", "", "b", "c"]
         StringUtils.splitPreserveAllTokens("a:b:c", '.')    = ["a:b:c"]
         StringUtils.splitPreserveAllTokens("a\tb\nc", null) = ["a", "b", "c"]
         StringUtils.splitPreserveAllTokens("a b c", ' ')    = ["a", "b", "c"]
         StringUtils.splitPreserveAllTokens("a b c ", ' ')   = ["a", "b", "c", ""]
         StringUtils.splitPreserveAllTokens("a b c  ", ' ')   = ["a", "b", "c", "", ""]
         StringUtils.splitPreserveAllTokens(" a b c", ' ')   = ["", a", "b", "c"]
         StringUtils.splitPreserveAllTokens("  a b c", ' ')  = ["", "", a", "b", "c"]
         StringUtils.splitPreserveAllTokens(" a b c ", ' ')  = ["", a", "b", "c", ""]
         
        Parameters:
        str - the String to parse, may be null
        separatorChar - the character used as the delimiter, null splits on whitespace
        Returns:
        an array of parsed Strings, null if null String input
        Since:
        2.1
      • splitPreserveAllTokens

        public static String[] splitPreserveAllTokens​(String str,
                                                      String separatorChars)

        Splits the provided text into an array, separators specified, preserving all tokens, including empty tokens created by adjacent separators. This is an alternative to using StringTokenizer.

        The separator is not included in the returned String array. Adjacent separators are treated as separators for empty tokens. For more control over the split use the StrTokenizer class.

        A null input String returns null. A null separatorChars splits on whitespace.

         StringUtils.splitPreserveAllTokens(null, *)           = null
         StringUtils.splitPreserveAllTokens("", *)             = []
         StringUtils.splitPreserveAllTokens("abc def", null)   = ["abc", "def"]
         StringUtils.splitPreserveAllTokens("abc def", " ")    = ["abc", "def"]
         StringUtils.splitPreserveAllTokens("abc  def", " ")   = ["abc", "", def"]
         StringUtils.splitPreserveAllTokens("ab:cd:ef", ":")   = ["ab", "cd", "ef"]
         StringUtils.splitPreserveAllTokens("ab:cd:ef:", ":")  = ["ab", "cd", "ef", ""]
         StringUtils.splitPreserveAllTokens("ab:cd:ef::", ":") = ["ab", "cd", "ef", "", ""]
         StringUtils.splitPreserveAllTokens("ab::cd:ef", ":")  = ["ab", "", cd", "ef"]
         StringUtils.splitPreserveAllTokens(":cd:ef", ":")     = ["", cd", "ef"]
         StringUtils.splitPreserveAllTokens("::cd:ef", ":")    = ["", "", cd", "ef"]
         StringUtils.splitPreserveAllTokens(":cd:ef:", ":")    = ["", cd", "ef", ""]
         
        Parameters:
        str - the String to parse, may be null
        separatorChars - the characters used as the delimiters, null splits on whitespace
        Returns:
        an array of parsed Strings, null if null String input
        Since:
        2.1
      • splitPreserveAllTokens

        public static String[] splitPreserveAllTokens​(String str,
                                                      String separatorChars,
                                                      int max)

        Splits the provided text into an array with a maximum length, separators specified, preserving all tokens, including empty tokens created by adjacent separators.

        The separator is not included in the returned String array. Adjacent separators are treated as separators for empty tokens. Adjacent separators are treated as one separator.

        A null input String returns null. A null separatorChars splits on whitespace.

        If more than max delimited substrings are found, the last returned string includes all characters after the first max - 1 returned strings (including separator characters).

         StringUtils.splitPreserveAllTokens(null, *, *)            = null
         StringUtils.splitPreserveAllTokens("", *, *)              = []
         StringUtils.splitPreserveAllTokens("ab de fg", null, 0)   = ["ab", "cd", "ef"]
         StringUtils.splitPreserveAllTokens("ab   de fg", null, 0) = ["ab", "cd", "ef"]
         StringUtils.splitPreserveAllTokens("ab:cd:ef", ":", 0)    = ["ab", "cd", "ef"]
         StringUtils.splitPreserveAllTokens("ab:cd:ef", ":", 2)    = ["ab", "cd:ef"]
         StringUtils.splitPreserveAllTokens("ab   de fg", null, 2) = ["ab", "  de fg"]
         StringUtils.splitPreserveAllTokens("ab   de fg", null, 3) = ["ab", "", " de fg"]
         StringUtils.splitPreserveAllTokens("ab   de fg", null, 4) = ["ab", "", "", "de fg"]
         
        Parameters:
        str - the String to parse, may be null
        separatorChars - the characters used as the delimiters, null splits on whitespace
        max - the maximum number of elements to include in the array. A zero or negative value implies no limit
        Returns:
        an array of parsed Strings, null if null String input
        Since:
        2.1
      • splitByCharacterType

        public static String[] splitByCharacterType​(String str)

        Splits a String by Character type as returned by java.lang.Character.getType(char). Groups of contiguous characters of the same type are returned as complete tokens.

         StringUtils.splitByCharacterType(null)         = null
         StringUtils.splitByCharacterType("")           = []
         StringUtils.splitByCharacterType("ab de fg")   = ["ab", " ", "de", " ", "fg"]
         StringUtils.splitByCharacterType("ab   de fg") = ["ab", "   ", "de", " ", "fg"]
         StringUtils.splitByCharacterType("ab:cd:ef")   = ["ab", ":", "cd", ":", "ef"]
         StringUtils.splitByCharacterType("number5")    = ["number", "5"]
         StringUtils.splitByCharacterType("fooBar")     = ["foo", "B", "ar"]
         StringUtils.splitByCharacterType("foo200Bar")  = ["foo", "200", "B", "ar"]
         StringUtils.splitByCharacterType("ASFRules")   = ["ASFR", "ules"]
         
        Parameters:
        str - the String to split, may be null
        Returns:
        an array of parsed Strings, null if null String input
        Since:
        2.4
      • splitByCharacterTypeCamelCase

        public static String[] splitByCharacterTypeCamelCase​(String str)

        Splits a String by Character type as returned by java.lang.Character.getType(char). Groups of contiguous characters of the same type are returned as complete tokens, with the following exception: the character of type Character.UPPERCASE_LETTER, if any, immediately preceding a token of type Character.LOWERCASE_LETTER will belong to the following token rather than to the preceding, if any, Character.UPPERCASE_LETTER token.

         StringUtils.splitByCharacterTypeCamelCase(null)         = null
         StringUtils.splitByCharacterTypeCamelCase("")           = []
         StringUtils.splitByCharacterTypeCamelCase("ab de fg")   = ["ab", " ", "de", " ", "fg"]
         StringUtils.splitByCharacterTypeCamelCase("ab   de fg") = ["ab", "   ", "de", " ", "fg"]
         StringUtils.splitByCharacterTypeCamelCase("ab:cd:ef")   = ["ab", ":", "cd", ":", "ef"]
         StringUtils.splitByCharacterTypeCamelCase("number5")    = ["number", "5"]
         StringUtils.splitByCharacterTypeCamelCase("fooBar")     = ["foo", "Bar"]
         StringUtils.splitByCharacterTypeCamelCase("foo200Bar")  = ["foo", "200", "Bar"]
         StringUtils.splitByCharacterTypeCamelCase("ASFRules")   = ["ASF", "Rules"]
         
        Parameters:
        str - the String to split, may be null
        Returns:
        an array of parsed Strings, null if null String input
        Since:
        2.4
      • concatenate

        public static String concatenate​(Object[] array)
        Deprecated.
        Use the better named join(Object[]) instead. Method will be removed in Commons Lang 3.0.

        Joins the provided elements into a single String.

        No separator is added to the joined String. Null objects or empty string elements are represented by empty strings.

         StringUtils.concatenate(null)            = null
         StringUtils.concatenate([])              = ""
         StringUtils.concatenate([null])          = ""
         StringUtils.concatenate(["a", "b", "c"]) = "abc"
         StringUtils.concatenate([null, "", "a"]) = "a"
         
        Parameters:
        array - the array of values to concatenate, may be null
        Returns:
        the concatenated String, null if null array input
      • join

        public static String join​(Object[] array)

        Joins the elements of the provided array into a single String containing the provided list of elements.

        No separator is added to the joined String. Null objects or empty strings within the array are represented by empty strings.

         StringUtils.join(null)            = null
         StringUtils.join([])              = ""
         StringUtils.join([null])          = ""
         StringUtils.join(["a", "b", "c"]) = "abc"
         StringUtils.join([null, "", "a"]) = "a"
         
        Parameters:
        array - the array of values to join together, may be null
        Returns:
        the joined String, null if null array input
        Since:
        2.0
      • join

        public static String join​(Object[] array,
                                  char separator)

        Joins the elements of the provided array into a single String containing the provided list of elements.

        No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.

         StringUtils.join(null, *)               = null
         StringUtils.join([], *)                 = ""
         StringUtils.join([null], *)             = ""
         StringUtils.join(["a", "b", "c"], ';')  = "a;b;c"
         StringUtils.join(["a", "b", "c"], null) = "abc"
         StringUtils.join([null, "", "a"], ';')  = ";;a"
         
        Parameters:
        array - the array of values to join together, may be null
        separator - the separator character to use
        Returns:
        the joined String, null if null array input
        Since:
        2.0
      • join

        public static String join​(Object[] array,
                                  char separator,
                                  int startIndex,
                                  int endIndex)

        Joins the elements of the provided array into a single String containing the provided list of elements.

        No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.

         StringUtils.join(null, *)               = null
         StringUtils.join([], *)                 = ""
         StringUtils.join([null], *)             = ""
         StringUtils.join(["a", "b", "c"], ';')  = "a;b;c"
         StringUtils.join(["a", "b", "c"], null) = "abc"
         StringUtils.join([null, "", "a"], ';')  = ";;a"
         
        Parameters:
        array - the array of values to join together, may be null
        separator - the separator character to use
        startIndex - the first index to start joining from. It is an error to pass in an end index past the end of the array
        endIndex - the index to stop joining from (exclusive). It is an error to pass in an end index past the end of the array
        Returns:
        the joined String, null if null array input
        Since:
        2.0
      • join

        public static String join​(Object[] array,
                                  String separator)

        Joins the elements of the provided array into a single String containing the provided list of elements.

        No delimiter is added before or after the list. A null separator is the same as an empty String (""). Null objects or empty strings within the array are represented by empty strings.

         StringUtils.join(null, *)                = null
         StringUtils.join([], *)                  = ""
         StringUtils.join([null], *)              = ""
         StringUtils.join(["a", "b", "c"], "--")  = "a--b--c"
         StringUtils.join(["a", "b", "c"], null)  = "abc"
         StringUtils.join(["a", "b", "c"], "")    = "abc"
         StringUtils.join([null, "", "a"], ',')   = ",,a"
         
        Parameters:
        array - the array of values to join together, may be null
        separator - the separator character to use, null treated as ""
        Returns:
        the joined String, null if null array input
      • join

        public static String join​(Object[] array,
                                  String separator,
                                  int startIndex,
                                  int endIndex)

        Joins the elements of the provided array into a single String containing the provided list of elements.

        No delimiter is added before or after the list. A null separator is the same as an empty String (""). Null objects or empty strings within the array are represented by empty strings.

         StringUtils.join(null, *)                = null
         StringUtils.join([], *)                  = ""
         StringUtils.join([null], *)              = ""
         StringUtils.join(["a", "b", "c"], "--")  = "a--b--c"
         StringUtils.join(["a", "b", "c"], null)  = "abc"
         StringUtils.join(["a", "b", "c"], "")    = "abc"
         StringUtils.join([null, "", "a"], ',')   = ",,a"
         
        Parameters:
        array - the array of values to join together, may be null
        separator - the separator character to use, null treated as ""
        startIndex - the first index to start joining from. It is an error to pass in an end index past the end of the array
        endIndex - the index to stop joining from (exclusive). It is an error to pass in an end index past the end of the array
        Returns:
        the joined String, null if null array input
      • join

        public static String join​(Iterator iterator,
                                  char separator)

        Joins the elements of the provided Iterator into a single String containing the provided elements.

        No delimiter is added before or after the list. Null objects or empty strings within the iteration are represented by empty strings.

        See the examples here: join(Object[],char).

        Parameters:
        iterator - the Iterator of values to join together, may be null
        separator - the separator character to use
        Returns:
        the joined String, null if null iterator input
        Since:
        2.0
      • join

        public static String join​(Iterator iterator,
                                  String separator)

        Joins the elements of the provided Iterator into a single String containing the provided elements.

        No delimiter is added before or after the list. A null separator is the same as an empty String ("").

        See the examples here: join(Object[],String).

        Parameters:
        iterator - the Iterator of values to join together, may be null
        separator - the separator character to use, null treated as ""
        Returns:
        the joined String, null if null iterator input
      • join

        public static String join​(Collection collection,
                                  char separator)

        Joins the elements of the provided Collection into a single String containing the provided elements.

        No delimiter is added before or after the list. Null objects or empty strings within the iteration are represented by empty strings.

        See the examples here: join(Object[],char).

        Parameters:
        collection - the Collection of values to join together, may be null
        separator - the separator character to use
        Returns:
        the joined String, null if null iterator input
        Since:
        2.3
      • join

        public static String join​(Collection collection,
                                  String separator)

        Joins the elements of the provided Collection into a single String containing the provided elements.

        No delimiter is added before or after the list. A null separator is the same as an empty String ("").

        See the examples here: join(Object[],String).

        Parameters:
        collection - the Collection of values to join together, may be null
        separator - the separator character to use, null treated as ""
        Returns:
        the joined String, null if null iterator input
        Since:
        2.3
      • deleteSpaces

        public static String deleteSpaces​(String str)
        Deprecated.
        Use the better localized deleteWhitespace(String). Method will be removed in Commons Lang 3.0.

        Deletes all 'space' characters from a String as defined by Character.isSpace(char).

        This is the only StringUtils method that uses the isSpace definition. You are advised to use deleteWhitespace(String) instead as whitespace is much better localized.

         StringUtils.deleteSpaces(null)           = null
         StringUtils.deleteSpaces("")             = ""
         StringUtils.deleteSpaces("abc")          = "abc"
         StringUtils.deleteSpaces(" \t  abc \n ") = "abc"
         StringUtils.deleteSpaces("ab  c")        = "abc"
         StringUtils.deleteSpaces("a\nb\tc     ") = "abc"
         

        Spaces are defined as {' ', '\t', '\r', '\n', '\b'} in line with the deprecated isSpace method.

        Parameters:
        str - the String to delete spaces from, may be null
        Returns:
        the String without 'spaces', null if null String input
      • deleteWhitespace

        public static String deleteWhitespace​(String str)

        Deletes all whitespaces from a String as defined by Character.isWhitespace(char).

         StringUtils.deleteWhitespace(null)         = null
         StringUtils.deleteWhitespace("")           = ""
         StringUtils.deleteWhitespace("abc")        = "abc"
         StringUtils.deleteWhitespace("   ab  c  ") = "abc"
         
        Parameters:
        str - the String to delete whitespace from, may be null
        Returns:
        the String without whitespaces, null if null String input
      • removeStart

        public static String removeStart​(String str,
                                         String remove)

        Removes a substring only if it is at the begining of a source string, otherwise returns the source string.

        A null source string will return null. An empty ("") source string will return the empty string. A null search string will return the source string.

         StringUtils.removeStart(null, *)      = null
         StringUtils.removeStart("", *)        = ""
         StringUtils.removeStart(*, null)      = *
         StringUtils.removeStart("www.domain.com", "www.")   = "domain.com"
         StringUtils.removeStart("domain.com", "www.")       = "domain.com"
         StringUtils.removeStart("www.domain.com", "domain") = "www.domain.com"
         StringUtils.removeStart("abc", "")    = "abc"
         
        Parameters:
        str - the source String to search, may be null
        remove - the String to search for and remove, may be null
        Returns:
        the substring with the string removed if found, null if null String input
        Since:
        2.1
      • removeStartIgnoreCase

        public static String removeStartIgnoreCase​(String str,
                                                   String remove)

        Case insensitive removal of a substring if it is at the begining of a source string, otherwise returns the source string.

        A null source string will return null. An empty ("") source string will return the empty string. A null search string will return the source string.

         StringUtils.removeStartIgnoreCase(null, *)      = null
         StringUtils.removeStartIgnoreCase("", *)        = ""
         StringUtils.removeStartIgnoreCase(*, null)      = *
         StringUtils.removeStartIgnoreCase("www.domain.com", "www.")   = "domain.com"
         StringUtils.removeStartIgnoreCase("www.domain.com", "WWW.")   = "domain.com"
         StringUtils.removeStartIgnoreCase("domain.com", "www.")       = "domain.com"
         StringUtils.removeStartIgnoreCase("www.domain.com", "domain") = "www.domain.com"
         StringUtils.removeStartIgnoreCase("abc", "")    = "abc"
         
        Parameters:
        str - the source String to search, may be null
        remove - the String to search for (case insensitive) and remove, may be null
        Returns:
        the substring with the string removed if found, null if null String input
        Since:
        2.4
      • removeEnd

        public static String removeEnd​(String str,
                                       String remove)

        Removes a substring only if it is at the end of a source string, otherwise returns the source string.

        A null source string will return null. An empty ("") source string will return the empty string. A null search string will return the source string.

         StringUtils.removeEnd(null, *)      = null
         StringUtils.removeEnd("", *)        = ""
         StringUtils.removeEnd(*, null)      = *
         StringUtils.removeEnd("www.domain.com", ".com.")  = "www.domain.com"
         StringUtils.removeEnd("www.domain.com", ".com")   = "www.domain"
         StringUtils.removeEnd("www.domain.com", "domain") = "www.domain.com"
         StringUtils.removeEnd("abc", "")    = "abc"
         
        Parameters:
        str - the source String to search, may be null
        remove - the String to search for and remove, may be null
        Returns:
        the substring with the string removed if found, null if null String input
        Since:
        2.1
      • removeEndIgnoreCase

        public static String removeEndIgnoreCase​(String str,
                                                 String remove)

        Case insensitive removal of a substring if it is at the end of a source string, otherwise returns the source string.

        A null source string will return null. An empty ("") source string will return the empty string. A null search string will return the source string.

         StringUtils.removeEndIgnoreCase(null, *)      = null
         StringUtils.removeEndIgnoreCase("", *)        = ""
         StringUtils.removeEndIgnoreCase(*, null)      = *
         StringUtils.removeEndIgnoreCase("www.domain.com", ".com.")  = "www.domain.com"
         StringUtils.removeEndIgnoreCase("www.domain.com", ".com")   = "www.domain"
         StringUtils.removeEndIgnoreCase("www.domain.com", "domain") = "www.domain.com"
         StringUtils.removeEndIgnoreCase("abc", "")    = "abc"
         StringUtils.removeEndIgnoreCase("www.domain.com", ".COM") = "www.domain")
         StringUtils.removeEndIgnoreCase("www.domain.COM", ".com") = "www.domain")
         
        Parameters:
        str - the source String to search, may be null
        remove - the String to search for (case insensitive) and remove, may be null
        Returns:
        the substring with the string removed if found, null if null String input
        Since:
        2.4
      • remove

        public static String remove​(String str,
                                    String remove)

        Removes all occurrences of a substring from within the source string.

        A null source string will return null. An empty ("") source string will return the empty string. A null remove string will return the source string. An empty ("") remove string will return the source string.

         StringUtils.remove(null, *)        = null
         StringUtils.remove("", *)          = ""
         StringUtils.remove(*, null)        = *
         StringUtils.remove(*, "")          = *
         StringUtils.remove("queued", "ue") = "qd"
         StringUtils.remove("queued", "zz") = "queued"
         
        Parameters:
        str - the source String to search, may be null
        remove - the String to search for and remove, may be null
        Returns:
        the substring with the string removed if found, null if null String input
        Since:
        2.1
      • remove

        public static String remove​(String str,
                                    char remove)

        Removes all occurrences of a character from within the source string.

        A null source string will return null. An empty ("") source string will return the empty string.

         StringUtils.remove(null, *)       = null
         StringUtils.remove("", *)         = ""
         StringUtils.remove("queued", 'u') = "qeed"
         StringUtils.remove("queued", 'z') = "queued"
         
        Parameters:
        str - the source String to search, may be null
        remove - the char to search for and remove, may be null
        Returns:
        the substring with the char removed if found, null if null String input
        Since:
        2.1
      • replaceOnce

        public static String replaceOnce​(String text,
                                         String searchString,
                                         String replacement)

        Replaces a String with another String inside a larger String, once.

        A null reference passed to this method is a no-op.

         StringUtils.replaceOnce(null, *, *)        = null
         StringUtils.replaceOnce("", *, *)          = ""
         StringUtils.replaceOnce("any", null, *)    = "any"
         StringUtils.replaceOnce("any", *, null)    = "any"
         StringUtils.replaceOnce("any", "", *)      = "any"
         StringUtils.replaceOnce("aba", "a", null)  = "aba"
         StringUtils.replaceOnce("aba", "a", "")    = "ba"
         StringUtils.replaceOnce("aba", "a", "z")   = "zba"
         
        Parameters:
        text - text to search and replace in, may be null
        searchString - the String to search for, may be null
        replacement - the String to replace with, may be null
        Returns:
        the text with any replacements processed, null if null String input
        See Also:
        replace(String text, String searchString, String replacement, int max)
      • replace

        public static String replace​(String text,
                                     String searchString,
                                     String replacement)

        Replaces all occurrences of a String within another String.

        A null reference passed to this method is a no-op.

         StringUtils.replace(null, *, *)        = null
         StringUtils.replace("", *, *)          = ""
         StringUtils.replace("any", null, *)    = "any"
         StringUtils.replace("any", *, null)    = "any"
         StringUtils.replace("any", "", *)      = "any"
         StringUtils.replace("aba", "a", null)  = "aba"
         StringUtils.replace("aba", "a", "")    = "b"
         StringUtils.replace("aba", "a", "z")   = "zbz"
         
        Parameters:
        text - text to search and replace in, may be null
        searchString - the String to search for, may be null
        replacement - the String to replace it with, may be null
        Returns:
        the text with any replacements processed, null if null String input
        See Also:
        replace(String text, String searchString, String replacement, int max)
      • replace

        public static String replace​(String text,
                                     String searchString,
                                     String replacement,
                                     int max)

        Replaces a String with another String inside a larger String, for the first max values of the search String.

        A null reference passed to this method is a no-op.

         StringUtils.replace(null, *, *, *)         = null
         StringUtils.replace("", *, *, *)           = ""
         StringUtils.replace("any", null, *, *)     = "any"
         StringUtils.replace("any", *, null, *)     = "any"
         StringUtils.replace("any", "", *, *)       = "any"
         StringUtils.replace("any", *, *, 0)        = "any"
         StringUtils.replace("abaa", "a", null, -1) = "abaa"
         StringUtils.replace("abaa", "a", "", -1)   = "b"
         StringUtils.replace("abaa", "a", "z", 0)   = "abaa"
         StringUtils.replace("abaa", "a", "z", 1)   = "zbaa"
         StringUtils.replace("abaa", "a", "z", 2)   = "zbza"
         StringUtils.replace("abaa", "a", "z", -1)  = "zbzz"
         
        Parameters:
        text - text to search and replace in, may be null
        searchString - the String to search for, may be null
        replacement - the String to replace it with, may be null
        max - maximum number of values to replace, or -1 if no maximum
        Returns:
        the text with any replacements processed, null if null String input
      • replaceEach

        public static String replaceEach​(String text,
                                         String[] searchList,
                                         String[] replacementList)

        Replaces all occurrences of Strings within another String.

        A null reference passed to this method is a no-op, or if any "search string" or "string to replace" is null, that replace will be ignored. This will not repeat. For repeating replaces, call the overloaded method.

          StringUtils.replaceEach(null, *, *)        = null
          StringUtils.replaceEach("", *, *)          = ""
          StringUtils.replaceEach("aba", null, null) = "aba"
          StringUtils.replaceEach("aba", new String[0], null) = "aba"
          StringUtils.replaceEach("aba", null, new String[0]) = "aba"
          StringUtils.replaceEach("aba", new String[]{"a"}, null)  = "aba"
          StringUtils.replaceEach("aba", new String[]{"a"}, new String[]{""})  = "b"
          StringUtils.replaceEach("aba", new String[]{null}, new String[]{"a"})  = "aba"
          StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"w", "t"})  = "wcte"
          (example of how it does not repeat)
          StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"d", "t"})  = "dcte"
         
        Parameters:
        text - text to search and replace in, no-op if null
        searchList - the Strings to search for, no-op if null
        replacementList - the Strings to replace them with, no-op if null
        Returns:
        the text with any replacements processed, null if null String input
        Throws:
        IndexOutOfBoundsException - if the lengths of the arrays are not the same (null is ok, and/or size 0)
        Since:
        2.4
      • replaceEachRepeatedly

        public static String replaceEachRepeatedly​(String text,
                                                   String[] searchList,
                                                   String[] replacementList)

        Replaces all occurrences of Strings within another String.

        A null reference passed to this method is a no-op, or if any "search string" or "string to replace" is null, that replace will be ignored. This will not repeat. For repeating replaces, call the overloaded method.

          StringUtils.replaceEach(null, *, *, *) = null
          StringUtils.replaceEach("", *, *, *) = ""
          StringUtils.replaceEach("aba", null, null, *) = "aba"
          StringUtils.replaceEach("aba", new String[0], null, *) = "aba"
          StringUtils.replaceEach("aba", null, new String[0], *) = "aba"
          StringUtils.replaceEach("aba", new String[]{"a"}, null, *) = "aba"
          StringUtils.replaceEach("aba", new String[]{"a"}, new String[]{""}, *) = "b"
          StringUtils.replaceEach("aba", new String[]{null}, new String[]{"a"}, *) = "aba"
          StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"w", "t"}, *) = "wcte"
          (example of how it repeats)
          StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"d", "t"}, false) = "dcte"
          StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"d", "t"}, true) = "tcte"
          StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"d", "ab"}, true) = IllegalArgumentException
          StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"d", "ab"}, false) = "dcabe"
         
        Parameters:
        text - text to search and replace in, no-op if null
        searchList - the Strings to search for, no-op if null
        replacementList - the Strings to replace them with, no-op if null
        Returns:
        the text with any replacements processed, null if null String input
        Throws:
        IllegalArgumentException - if the search is repeating and there is an endless loop due to outputs of one being inputs to another
        IndexOutOfBoundsException - if the lengths of the arrays are not the same (null is ok, and/or size 0)
        Since:
        2.4
      • replaceChars

        public static String replaceChars​(String str,
                                          char searchChar,
                                          char replaceChar)

        Replaces all occurrences of a character in a String with another. This is a null-safe version of String.replace(char, char).

        A null string input returns null. An empty ("") string input returns an empty string.

         StringUtils.replaceChars(null, *, *)        = null
         StringUtils.replaceChars("", *, *)          = ""
         StringUtils.replaceChars("abcba", 'b', 'y') = "aycya"
         StringUtils.replaceChars("abcba", 'z', 'y') = "abcba"
         
        Parameters:
        str - String to replace characters in, may be null
        searchChar - the character to search for, may be null
        replaceChar - the character to replace, may be null
        Returns:
        modified String, null if null string input
        Since:
        2.0
      • replaceChars

        public static String replaceChars​(String str,
                                          String searchChars,
                                          String replaceChars)

        Replaces multiple characters in a String in one go. This method can also be used to delete characters.

        For example:
        replaceChars("hello", "ho", "jy") = jelly.

        A null string input returns null. An empty ("") string input returns an empty string. A null or empty set of search characters returns the input string.

        The length of the search characters should normally equal the length of the replace characters. If the search characters is longer, then the extra search characters are deleted. If the search characters is shorter, then the extra replace characters are ignored.

         StringUtils.replaceChars(null, *, *)           = null
         StringUtils.replaceChars("", *, *)             = ""
         StringUtils.replaceChars("abc", null, *)       = "abc"
         StringUtils.replaceChars("abc", "", *)         = "abc"
         StringUtils.replaceChars("abc", "b", null)     = "ac"
         StringUtils.replaceChars("abc", "b", "")       = "ac"
         StringUtils.replaceChars("abcba", "bc", "yz")  = "ayzya"
         StringUtils.replaceChars("abcba", "bc", "y")   = "ayya"
         StringUtils.replaceChars("abcba", "bc", "yzx") = "ayzya"
         
        Parameters:
        str - String to replace characters in, may be null
        searchChars - a set of characters to search for, may be null
        replaceChars - a set of characters to replace, may be null
        Returns:
        modified String, null if null string input
        Since:
        2.0
      • overlayString

        public static String overlayString​(String text,
                                           String overlay,
                                           int start,
                                           int end)
        Deprecated.
        Use better named overlay(String, String, int, int) instead. Method will be removed in Commons Lang 3.0.

        Overlays part of a String with another String.

         StringUtils.overlayString(null, *, *, *)           = NullPointerException
         StringUtils.overlayString(*, null, *, *)           = NullPointerException
         StringUtils.overlayString("", "abc", 0, 0)         = "abc"
         StringUtils.overlayString("abcdef", null, 2, 4)    = "abef"
         StringUtils.overlayString("abcdef", "", 2, 4)      = "abef"
         StringUtils.overlayString("abcdef", "zzzz", 2, 4)  = "abzzzzef"
         StringUtils.overlayString("abcdef", "zzzz", 4, 2)  = "abcdzzzzcdef"
         StringUtils.overlayString("abcdef", "zzzz", -1, 4) = IndexOutOfBoundsException
         StringUtils.overlayString("abcdef", "zzzz", 2, 8)  = IndexOutOfBoundsException
         
        Parameters:
        text - the String to do overlaying in, may be null
        overlay - the String to overlay, may be null
        start - the position to start overlaying at, must be valid
        end - the position to stop overlaying before, must be valid
        Returns:
        overlayed String, null if null String input
        Throws:
        NullPointerException - if text or overlay is null
        IndexOutOfBoundsException - if either position is invalid
      • overlay

        public static String overlay​(String str,
                                     String overlay,
                                     int start,
                                     int end)

        Overlays part of a String with another String.

        A null string input returns null. A negative index is treated as zero. An index greater than the string length is treated as the string length. The start index is always the smaller of the two indices.

         StringUtils.overlay(null, *, *, *)            = null
         StringUtils.overlay("", "abc", 0, 0)          = "abc"
         StringUtils.overlay("abcdef", null, 2, 4)     = "abef"
         StringUtils.overlay("abcdef", "", 2, 4)       = "abef"
         StringUtils.overlay("abcdef", "", 4, 2)       = "abef"
         StringUtils.overlay("abcdef", "zzzz", 2, 4)   = "abzzzzef"
         StringUtils.overlay("abcdef", "zzzz", 4, 2)   = "abzzzzef"
         StringUtils.overlay("abcdef", "zzzz", -1, 4)  = "zzzzef"
         StringUtils.overlay("abcdef", "zzzz", 2, 8)   = "abzzzz"
         StringUtils.overlay("abcdef", "zzzz", -2, -3) = "zzzzabcdef"
         StringUtils.overlay("abcdef", "zzzz", 8, 10)  = "abcdefzzzz"
         
        Parameters:
        str - the String to do overlaying in, may be null
        overlay - the String to overlay, may be null
        start - the position to start overlaying at
        end - the position to stop overlaying before
        Returns:
        overlayed String, null if null String input
        Since:
        2.0
      • chomp

        public static String chomp​(String str)

        Removes one newline from end of a String if it's there, otherwise leave it alone. A newline is "\n", "\r", or "\r\n".

        NOTE: This method changed in 2.0. It now more closely matches Perl chomp.

         StringUtils.chomp(null)          = null
         StringUtils.chomp("")            = ""
         StringUtils.chomp("abc \r")      = "abc "
         StringUtils.chomp("abc\n")       = "abc"
         StringUtils.chomp("abc\r\n")     = "abc"
         StringUtils.chomp("abc\r\n\r\n") = "abc\r\n"
         StringUtils.chomp("abc\n\r")     = "abc\n"
         StringUtils.chomp("abc\n\rabc")  = "abc\n\rabc"
         StringUtils.chomp("\r")          = ""
         StringUtils.chomp("\n")          = ""
         StringUtils.chomp("\r\n")        = ""
         
        Parameters:
        str - the String to chomp a newline from, may be null
        Returns:
        String without newline, null if null String input
      • chomp

        public static String chomp​(String str,
                                   String separator)

        Removes separator from the end of str if it's there, otherwise leave it alone.

        NOTE: This method changed in version 2.0. It now more closely matches Perl chomp. For the previous behavior, use substringBeforeLast(String, String). This method uses String.endsWith(String).

         StringUtils.chomp(null, *)         = null
         StringUtils.chomp("", *)           = ""
         StringUtils.chomp("foobar", "bar") = "foo"
         StringUtils.chomp("foobar", "baz") = "foobar"
         StringUtils.chomp("foo", "foo")    = ""
         StringUtils.chomp("foo ", "foo")   = "foo "
         StringUtils.chomp(" foo", "foo")   = " "
         StringUtils.chomp("foo", "foooo")  = "foo"
         StringUtils.chomp("foo", "")       = "foo"
         StringUtils.chomp("foo", null)     = "foo"
         
        Parameters:
        str - the String to chomp from, may be null
        separator - separator String, may be null
        Returns:
        String without trailing separator, null if null String input
      • chompLast

        public static String chompLast​(String str)
        Deprecated.
        Use chomp(String) instead. Method will be removed in Commons Lang 3.0.

        Remove any "\n" if and only if it is at the end of the supplied String.

        Parameters:
        str - the String to chomp from, must not be null
        Returns:
        String without chomped ending
        Throws:
        NullPointerException - if str is null
      • chompLast

        public static String chompLast​(String str,
                                       String sep)
        Deprecated.
        Use chomp(String,String) instead. Method will be removed in Commons Lang 3.0.

        Remove a value if and only if the String ends with that value.

        Parameters:
        str - the String to chomp from, must not be null
        sep - the String to chomp, must not be null
        Returns:
        String without chomped ending
        Throws:
        NullPointerException - if str or sep is null
      • getChomp

        public static String getChomp​(String str,
                                      String sep)
        Deprecated.
        Use substringAfterLast(String, String) instead (although this doesn't include the separator) Method will be removed in Commons Lang 3.0.

        Remove everything and return the last value of a supplied String, and everything after it from a String.

        Parameters:
        str - the String to chomp from, must not be null
        sep - the String to chomp, must not be null
        Returns:
        String chomped
        Throws:
        NullPointerException - if str or sep is null
      • prechomp

        public static String prechomp​(String str,
                                      String sep)
        Deprecated.
        Use substringAfter(String,String) instead. Method will be removed in Commons Lang 3.0.

        Remove the first value of a supplied String, and everything before it from a String.

        Parameters:
        str - the String to chomp from, must not be null
        sep - the String to chomp, must not be null
        Returns:
        String without chomped beginning
        Throws:
        NullPointerException - if str or sep is null
      • getPrechomp

        public static String getPrechomp​(String str,
                                         String sep)
        Deprecated.
        Use substringBefore(String,String) instead (although this doesn't include the separator). Method will be removed in Commons Lang 3.0.

        Remove and return everything before the first value of a supplied String from another String.

        Parameters:
        str - the String to chomp from, must not be null
        sep - the String to chomp, must not be null
        Returns:
        String prechomped
        Throws:
        NullPointerException - if str or sep is null
      • chop

        public static String chop​(String str)

        Remove the last character from a String.

        If the String ends in \r\n, then remove both of them.

         StringUtils.chop(null)          = null
         StringUtils.chop("")            = ""
         StringUtils.chop("abc \r")      = "abc "
         StringUtils.chop("abc\n")       = "abc"
         StringUtils.chop("abc\r\n")     = "abc"
         StringUtils.chop("abc")         = "ab"
         StringUtils.chop("abc\nabc")    = "abc\nab"
         StringUtils.chop("a")           = ""
         StringUtils.chop("\r")          = ""
         StringUtils.chop("\n")          = ""
         StringUtils.chop("\r\n")        = ""
         
        Parameters:
        str - the String to chop last character from, may be null
        Returns:
        String without last character, null if null String input
      • chopNewline

        public static String chopNewline​(String str)
        Deprecated.
        Use chomp(String) instead. Method will be removed in Commons Lang 3.0.

        Removes \n from end of a String if it's there. If a \r precedes it, then remove that too.

        Parameters:
        str - the String to chop a newline from, must not be null
        Returns:
        String without newline
        Throws:
        NullPointerException - if str is null
      • repeat

        public static String repeat​(String str,
                                    int repeat)

        Repeat a String repeat times to form a new String.

         StringUtils.repeat(null, 2) = null
         StringUtils.repeat("", 0)   = ""
         StringUtils.repeat("", 2)   = ""
         StringUtils.repeat("a", 3)  = "aaa"
         StringUtils.repeat("ab", 2) = "abab"
         StringUtils.repeat("a", -2) = ""
         
        Parameters:
        str - the String to repeat, may be null
        repeat - number of times to repeat str, negative treated as zero
        Returns:
        a new String consisting of the original String repeated, null if null String input
      • repeat

        public static String repeat​(String str,
                                    String separator,
                                    int repeat)

        Repeat a String repeat times to form a new String, with a String separator injected each time.

         StringUtils.repeat(null, null, 2) = null
         StringUtils.repeat(null, "x", 2)  = null
         StringUtils.repeat("", null, 0)   = ""
         StringUtils.repeat("", "", 2)     = ""
         StringUtils.repeat("", "x", 3)    = "xxx"
         StringUtils.repeat("?", ", ", 3)  = "?, ?, ?"
         
        Parameters:
        str - the String to repeat, may be null
        separator - the String to inject, may be null
        repeat - number of times to repeat str, negative treated as zero
        Returns:
        a new String consisting of the original String repeated, null if null String input
        Since:
        2.5
      • rightPad

        public static String rightPad​(String str,
                                      int size)

        Right pad a String with spaces (' ').

        The String is padded to the size of size.

         StringUtils.rightPad(null, *)   = null
         StringUtils.rightPad("", 3)     = "   "
         StringUtils.rightPad("bat", 3)  = "bat"
         StringUtils.rightPad("bat", 5)  = "bat  "
         StringUtils.rightPad("bat", 1)  = "bat"
         StringUtils.rightPad("bat", -1) = "bat"
         
        Parameters:
        str - the String to pad out, may be null
        size - the size to pad to
        Returns:
        right padded String or original String if no padding is necessary, null if null String input
      • rightPad

        public static String rightPad​(String str,
                                      int size,
                                      char padChar)

        Right pad a String with a specified character.

        The String is padded to the size of size.

         StringUtils.rightPad(null, *, *)     = null
         StringUtils.rightPad("", 3, 'z')     = "zzz"
         StringUtils.rightPad("bat", 3, 'z')  = "bat"
         StringUtils.rightPad("bat", 5, 'z')  = "batzz"
         StringUtils.rightPad("bat", 1, 'z')  = "bat"
         StringUtils.rightPad("bat", -1, 'z') = "bat"
         
        Parameters:
        str - the String to pad out, may be null
        size - the size to pad to
        padChar - the character to pad with
        Returns:
        right padded String or original String if no padding is necessary, null if null String input
        Since:
        2.0
      • rightPad

        public static String rightPad​(String str,
                                      int size,
                                      String padStr)

        Right pad a String with a specified String.

        The String is padded to the size of size.

         StringUtils.rightPad(null, *, *)      = null
         StringUtils.rightPad("", 3, "z")      = "zzz"
         StringUtils.rightPad("bat", 3, "yz")  = "bat"
         StringUtils.rightPad("bat", 5, "yz")  = "batyz"
         StringUtils.rightPad("bat", 8, "yz")  = "batyzyzy"
         StringUtils.rightPad("bat", 1, "yz")  = "bat"
         StringUtils.rightPad("bat", -1, "yz") = "bat"
         StringUtils.rightPad("bat", 5, null)  = "bat  "
         StringUtils.rightPad("bat", 5, "")    = "bat  "
         
        Parameters:
        str - the String to pad out, may be null
        size - the size to pad to
        padStr - the String to pad with, null or empty treated as single space
        Returns:
        right padded String or original String if no padding is necessary, null if null String input
      • leftPad

        public static String leftPad​(String str,
                                     int size)

        Left pad a String with spaces (' ').

        The String is padded to the size of size.

         StringUtils.leftPad(null, *)   = null
         StringUtils.leftPad("", 3)     = "   "
         StringUtils.leftPad("bat", 3)  = "bat"
         StringUtils.leftPad("bat", 5)  = "  bat"
         StringUtils.leftPad("bat", 1)  = "bat"
         StringUtils.leftPad("bat", -1) = "bat"
         
        Parameters:
        str - the String to pad out, may be null
        size - the size to pad to
        Returns:
        left padded String or original String if no padding is necessary, null if null String input
      • leftPad

        public static String leftPad​(String str,
                                     int size,
                                     char padChar)

        Left pad a String with a specified character.

        Pad to a size of size.

         StringUtils.leftPad(null, *, *)     = null
         StringUtils.leftPad("", 3, 'z')     = "zzz"
         StringUtils.leftPad("bat", 3, 'z')  = "bat"
         StringUtils.leftPad("bat", 5, 'z')  = "zzbat"
         StringUtils.leftPad("bat", 1, 'z')  = "bat"
         StringUtils.leftPad("bat", -1, 'z') = "bat"
         
        Parameters:
        str - the String to pad out, may be null
        size - the size to pad to
        padChar - the character to pad with
        Returns:
        left padded String or original String if no padding is necessary, null if null String input
        Since:
        2.0
      • leftPad

        public static String leftPad​(String str,
                                     int size,
                                     String padStr)

        Left pad a String with a specified String.

        Pad to a size of size.

         StringUtils.leftPad(null, *, *)      = null
         StringUtils.leftPad("", 3, "z")      = "zzz"
         StringUtils.leftPad("bat", 3, "yz")  = "bat"
         StringUtils.leftPad("bat", 5, "yz")  = "yzbat"
         StringUtils.leftPad("bat", 8, "yz")  = "yzyzybat"
         StringUtils.leftPad("bat", 1, "yz")  = "bat"
         StringUtils.leftPad("bat", -1, "yz") = "bat"
         StringUtils.leftPad("bat", 5, null)  = "  bat"
         StringUtils.leftPad("bat", 5, "")    = "  bat"
         
        Parameters:
        str - the String to pad out, may be null
        size - the size to pad to
        padStr - the String to pad with, null or empty treated as single space
        Returns:
        left padded String or original String if no padding is necessary, null if null String input
      • length

        public static int length​(String str)
        Gets a String's length or 0 if the String is null.
        Parameters:
        str - a String or null
        Returns:
        String length or 0 if the String is null.
        Since:
        2.4
      • center

        public static String center​(String str,
                                    int size)

        Centers a String in a larger String of size size using the space character (' ').

        If the size is less than the String length, the String is returned. A null String returns null. A negative size is treated as zero.

        Equivalent to center(str, size, " ").

         StringUtils.center(null, *)   = null
         StringUtils.center("", 4)     = "    "
         StringUtils.center("ab", -1)  = "ab"
         StringUtils.center("ab", 4)   = " ab "
         StringUtils.center("abcd", 2) = "abcd"
         StringUtils.center("a", 4)    = " a  "
         
        Parameters:
        str - the String to center, may be null
        size - the int size of new String, negative treated as zero
        Returns:
        centered String, null if null String input
      • center

        public static String center​(String str,
                                    int size,
                                    char padChar)

        Centers a String in a larger String of size size. Uses a supplied character as the value to pad the String with.

        If the size is less than the String length, the String is returned. A null String returns null. A negative size is treated as zero.

         StringUtils.center(null, *, *)     = null
         StringUtils.center("", 4, ' ')     = "    "
         StringUtils.center("ab", -1, ' ')  = "ab"
         StringUtils.center("ab", 4, ' ')   = " ab"
         StringUtils.center("abcd", 2, ' ') = "abcd"
         StringUtils.center("a", 4, ' ')    = " a  "
         StringUtils.center("a", 4, 'y')    = "yayy"
         
        Parameters:
        str - the String to center, may be null
        size - the int size of new String, negative treated as zero
        padChar - the character to pad the new String with
        Returns:
        centered String, null if null String input
        Since:
        2.0
      • center

        public static String center​(String str,
                                    int size,
                                    String padStr)

        Centers a String in a larger String of size size. Uses a supplied String as the value to pad the String with.

        If the size is less than the String length, the String is returned. A null String returns null. A negative size is treated as zero.

         StringUtils.center(null, *, *)     = null
         StringUtils.center("", 4, " ")     = "    "
         StringUtils.center("ab", -1, " ")  = "ab"
         StringUtils.center("ab", 4, " ")   = " ab"
         StringUtils.center("abcd", 2, " ") = "abcd"
         StringUtils.center("a", 4, " ")    = " a  "
         StringUtils.center("a", 4, "yz")   = "yayz"
         StringUtils.center("abc", 7, null) = "  abc  "
         StringUtils.center("abc", 7, "")   = "  abc  "
         
        Parameters:
        str - the String to center, may be null
        size - the int size of new String, negative treated as zero
        padStr - the String to pad the new String with, must not be null or empty
        Returns:
        centered String, null if null String input
        Throws:
        IllegalArgumentException - if padStr is null or empty
      • upperCase

        public static String upperCase​(String str)

        Converts a String to upper case as per String.toUpperCase().

        A null input String returns null.

         StringUtils.upperCase(null)  = null
         StringUtils.upperCase("")    = ""
         StringUtils.upperCase("aBc") = "ABC"
         

        Note: As described in the documentation for String.toUpperCase(), the result of this method is affected by the current locale. For platform-independent case transformations, the method lowerCase(String, Locale) should be used with a specific locale (e.g. Locale.ENGLISH).

        Parameters:
        str - the String to upper case, may be null
        Returns:
        the upper cased String, null if null String input
      • upperCase

        public static String upperCase​(String str,
                                       Locale locale)

        Converts a String to upper case as per String.toUpperCase(Locale).

        A null input String returns null.

         StringUtils.upperCase(null, Locale.ENGLISH)  = null
         StringUtils.upperCase("", Locale.ENGLISH)    = ""
         StringUtils.upperCase("aBc", Locale.ENGLISH) = "ABC"
         
        Parameters:
        str - the String to upper case, may be null
        locale - the locale that defines the case transformation rules, must not be null
        Returns:
        the upper cased String, null if null String input
        Since:
        2.5
      • lowerCase

        public static String lowerCase​(String str)

        Converts a String to lower case as per String.toLowerCase().

        A null input String returns null.

         StringUtils.lowerCase(null)  = null
         StringUtils.lowerCase("")    = ""
         StringUtils.lowerCase("aBc") = "abc"
         

        Note: As described in the documentation for String.toLowerCase(), the result of this method is affected by the current locale. For platform-independent case transformations, the method lowerCase(String, Locale) should be used with a specific locale (e.g. Locale.ENGLISH).

        Parameters:
        str - the String to lower case, may be null
        Returns:
        the lower cased String, null if null String input
      • lowerCase

        public static String lowerCase​(String str,
                                       Locale locale)

        Converts a String to lower case as per String.toLowerCase(Locale).

        A null input String returns null.

         StringUtils.lowerCase(null, Locale.ENGLISH)  = null
         StringUtils.lowerCase("", Locale.ENGLISH)    = ""
         StringUtils.lowerCase("aBc", Locale.ENGLISH) = "abc"
         
        Parameters:
        str - the String to lower case, may be null
        locale - the locale that defines the case transformation rules, must not be null
        Returns:
        the lower cased String, null if null String input
        Since:
        2.5
      • capitalize

        public static String capitalize​(String str)

        Capitalizes a String changing the first letter to title case as per Character.toTitleCase(char). No other letters are changed.

        For a word based algorithm, see WordUtils.capitalize(String). A null input String returns null.

         StringUtils.capitalize(null)  = null
         StringUtils.capitalize("")    = ""
         StringUtils.capitalize("cat") = "Cat"
         StringUtils.capitalize("cAt") = "CAt"
         
        Parameters:
        str - the String to capitalize, may be null
        Returns:
        the capitalized String, null if null String input
        Since:
        2.0
        See Also:
        WordUtils.capitalize(String), uncapitalize(String)
      • capitalise

        public static String capitalise​(String str)
        Deprecated.
        Use the standardly named capitalize(String). Method will be removed in Commons Lang 3.0.

        Capitalizes a String changing the first letter to title case as per Character.toTitleCase(char). No other letters are changed.

        Parameters:
        str - the String to capitalize, may be null
        Returns:
        the capitalized String, null if null String input
      • uncapitalize

        public static String uncapitalize​(String str)

        Uncapitalizes a String changing the first letter to title case as per Character.toLowerCase(char). No other letters are changed.

        For a word based algorithm, see WordUtils.uncapitalize(String). A null input String returns null.

         StringUtils.uncapitalize(null)  = null
         StringUtils.uncapitalize("")    = ""
         StringUtils.uncapitalize("Cat") = "cat"
         StringUtils.uncapitalize("CAT") = "cAT"
         
        Parameters:
        str - the String to uncapitalize, may be null
        Returns:
        the uncapitalized String, null if null String input
        Since:
        2.0
        See Also:
        WordUtils.uncapitalize(String), capitalize(String)
      • uncapitalise

        public static String uncapitalise​(String str)
        Deprecated.
        Use the standardly named uncapitalize(String). Method will be removed in Commons Lang 3.0.

        Uncapitalizes a String changing the first letter to title case as per Character.toLowerCase(char). No other letters are changed.

        Parameters:
        str - the String to uncapitalize, may be null
        Returns:
        the uncapitalized String, null if null String input
      • swapCase

        public static String swapCase​(String str)

        Swaps the case of a String changing upper and title case to lower case, and lower case to upper case.

        • Upper case character converts to Lower case
        • Title case character converts to Lower case
        • Lower case character converts to Upper case

        For a word based algorithm, see WordUtils.swapCase(String). A null input String returns null.

         StringUtils.swapCase(null)                 = null
         StringUtils.swapCase("")                   = ""
         StringUtils.swapCase("The dog has a BONE") = "tHE DOG HAS A bone"
         

        NOTE: This method changed in Lang version 2.0. It no longer performs a word based algorithm. If you only use ASCII, you will notice no change. That functionality is available in WordUtils.

        Parameters:
        str - the String to swap case, may be null
        Returns:
        the changed String, null if null String input
      • capitaliseAllWords

        public static String capitaliseAllWords​(String str)
        Deprecated.
        Use the relocated WordUtils.capitalize(String). Method will be removed in Commons Lang 3.0.

        Capitalizes all the whitespace separated words in a String. Only the first letter of each word is changed.

        Whitespace is defined by Character.isWhitespace(char). A null input String returns null.

        Parameters:
        str - the String to capitalize, may be null
        Returns:
        capitalized String, null if null String input
      • countMatches

        public static int countMatches​(String str,
                                       String sub)

        Counts how many times the substring appears in the larger String.

        A null or empty ("") String input returns 0.

         StringUtils.countMatches(null, *)       = 0
         StringUtils.countMatches("", *)         = 0
         StringUtils.countMatches("abba", null)  = 0
         StringUtils.countMatches("abba", "")    = 0
         StringUtils.countMatches("abba", "a")   = 2
         StringUtils.countMatches("abba", "ab")  = 1
         StringUtils.countMatches("abba", "xxx") = 0
         
        Parameters:
        str - the String to check, may be null
        sub - the substring to count, may be null
        Returns:
        the number of occurrences, 0 if either String is null
      • isAlpha

        public static boolean isAlpha​(String str)

        Checks if the String contains only unicode letters.

        null will return false. An empty String (length()=0) will return true.

         StringUtils.isAlpha(null)   = false
         StringUtils.isAlpha("")     = true
         StringUtils.isAlpha("  ")   = false
         StringUtils.isAlpha("abc")  = true
         StringUtils.isAlpha("ab2c") = false
         StringUtils.isAlpha("ab-c") = false
         
        Parameters:
        str - the String to check, may be null
        Returns:
        true if only contains letters, and is non-null
      • isAlphaSpace

        public static boolean isAlphaSpace​(String str)

        Checks if the String contains only unicode letters and space (' ').

        null will return false An empty String (length()=0) will return true.

         StringUtils.isAlphaSpace(null)   = false
         StringUtils.isAlphaSpace("")     = true
         StringUtils.isAlphaSpace("  ")   = true
         StringUtils.isAlphaSpace("abc")  = true
         StringUtils.isAlphaSpace("ab c") = true
         StringUtils.isAlphaSpace("ab2c") = false
         StringUtils.isAlphaSpace("ab-c") = false
         
        Parameters:
        str - the String to check, may be null
        Returns:
        true if only contains letters and space, and is non-null
      • isAlphanumeric

        public static boolean isAlphanumeric​(String str)

        Checks if the String contains only unicode letters or digits.

        null will return false. An empty String (length()=0) will return true.

         StringUtils.isAlphanumeric(null)   = false
         StringUtils.isAlphanumeric("")     = true
         StringUtils.isAlphanumeric("  ")   = false
         StringUtils.isAlphanumeric("abc")  = true
         StringUtils.isAlphanumeric("ab c") = false
         StringUtils.isAlphanumeric("ab2c") = true
         StringUtils.isAlphanumeric("ab-c") = false
         
        Parameters:
        str - the String to check, may be null
        Returns:
        true if only contains letters or digits, and is non-null
      • isAlphanumericSpace

        public static boolean isAlphanumericSpace​(String str)

        Checks if the String contains only unicode letters, digits or space (' ').

        null will return false. An empty String (length()=0) will return true.

         StringUtils.isAlphanumeric(null)   = false
         StringUtils.isAlphanumeric("")     = true
         StringUtils.isAlphanumeric("  ")   = true
         StringUtils.isAlphanumeric("abc")  = true
         StringUtils.isAlphanumeric("ab c") = true
         StringUtils.isAlphanumeric("ab2c") = true
         StringUtils.isAlphanumeric("ab-c") = false
         
        Parameters:
        str - the String to check, may be null
        Returns:
        true if only contains letters, digits or space, and is non-null
      • isAsciiPrintable

        public static boolean isAsciiPrintable​(String str)

        Checks if the string contains only ASCII printable characters.

        null will return false. An empty String (length()=0) will return true.

         StringUtils.isAsciiPrintable(null)     = false
         StringUtils.isAsciiPrintable("")       = true
         StringUtils.isAsciiPrintable(" ")      = true
         StringUtils.isAsciiPrintable("Ceki")   = true
         StringUtils.isAsciiPrintable("ab2c")   = true
         StringUtils.isAsciiPrintable("!ab-c~") = true
         StringUtils.isAsciiPrintable(" ") = true
         StringUtils.isAsciiPrintable("!") = true
         StringUtils.isAsciiPrintable("~") = true
         StringUtils.isAsciiPrintable("") = false
         StringUtils.isAsciiPrintable("Ceki Gülcü") = false
         
        Parameters:
        str - the string to check, may be null
        Returns:
        true if every character is in the range 32 thru 126
        Since:
        2.1
      • isNumeric

        public static boolean isNumeric​(String str)

        Checks if the String contains only unicode digits. A decimal point is not a unicode digit and returns false.

        null will return false. An empty String (length()=0) will return true.

         StringUtils.isNumeric(null)   = false
         StringUtils.isNumeric("")     = true
         StringUtils.isNumeric("  ")   = false
         StringUtils.isNumeric("123")  = true
         StringUtils.isNumeric("12 3") = false
         StringUtils.isNumeric("ab2c") = false
         StringUtils.isNumeric("12-3") = false
         StringUtils.isNumeric("12.3") = false
         
        Parameters:
        str - the String to check, may be null
        Returns:
        true if only contains digits, and is non-null
      • isNumericSpace

        public static boolean isNumericSpace​(String str)

        Checks if the String contains only unicode digits or space (' '). A decimal point is not a unicode digit and returns false.

        null will return false. An empty String (length()=0) will return true.

         StringUtils.isNumeric(null)   = false
         StringUtils.isNumeric("")     = true
         StringUtils.isNumeric("  ")   = true
         StringUtils.isNumeric("123")  = true
         StringUtils.isNumeric("12 3") = true
         StringUtils.isNumeric("ab2c") = false
         StringUtils.isNumeric("12-3") = false
         StringUtils.isNumeric("12.3") = false
         
        Parameters:
        str - the String to check, may be null
        Returns:
        true if only contains digits or space, and is non-null
      • isWhitespace

        public static boolean isWhitespace​(String str)

        Checks if the String contains only whitespace.

        null will return false. An empty String (length()=0) will return true.

         StringUtils.isWhitespace(null)   = false
         StringUtils.isWhitespace("")     = true
         StringUtils.isWhitespace("  ")   = true
         StringUtils.isWhitespace("abc")  = false
         StringUtils.isWhitespace("ab2c") = false
         StringUtils.isWhitespace("ab-c") = false
         
        Parameters:
        str - the String to check, may be null
        Returns:
        true if only contains whitespace, and is non-null
        Since:
        2.0
      • isAllLowerCase

        public static boolean isAllLowerCase​(String str)

        Checks if the String contains only lowercase characters.

        null will return false. An empty String (length()=0) will return false.

         StringUtils.isAllLowerCase(null)   = false
         StringUtils.isAllLowerCase("")     = false
         StringUtils.isAllLowerCase("  ")   = false
         StringUtils.isAllLowerCase("abc")  = true
         StringUtils.isAllLowerCase("abC") = false
         
        Parameters:
        str - the String to check, may be null
        Returns:
        true if only contains lowercase characters, and is non-null
        Since:
        2.5
      • isAllUpperCase

        public static boolean isAllUpperCase​(String str)

        Checks if the String contains only uppercase characters.

        null will return false. An empty String (length()=0) will return false.

         StringUtils.isAllUpperCase(null)   = false
         StringUtils.isAllUpperCase("")     = false
         StringUtils.isAllUpperCase("  ")   = false
         StringUtils.isAllUpperCase("ABC")  = true
         StringUtils.isAllUpperCase("aBC") = false
         
        Parameters:
        str - the String to check, may be null
        Returns:
        true if only contains uppercase characters, and is non-null
        Since:
        2.5
      • defaultString

        public static String defaultString​(String str)

        Returns either the passed in String, or if the String is null, an empty String ("").

         StringUtils.defaultString(null)  = ""
         StringUtils.defaultString("")    = ""
         StringUtils.defaultString("bat") = "bat"
         
        Parameters:
        str - the String to check, may be null
        Returns:
        the passed in String, or the empty String if it was null
        See Also:
        ObjectUtils.toString(Object), String.valueOf(Object)
      • defaultString

        public static String defaultString​(String str,
                                           String defaultStr)

        Returns either the passed in String, or if the String is null, the value of defaultStr.

         StringUtils.defaultString(null, "NULL")  = "NULL"
         StringUtils.defaultString("", "NULL")    = ""
         StringUtils.defaultString("bat", "NULL") = "bat"
         
        Parameters:
        str - the String to check, may be null
        defaultStr - the default String to return if the input is null, may be null
        Returns:
        the passed in String, or the default if it was null
        See Also:
        ObjectUtils.toString(Object,String), String.valueOf(Object)
      • defaultIfBlank

        public static String defaultIfBlank​(String str,
                                            String defaultStr)

        Returns either the passed in String, or if the String is whitespace, empty ("") or null, the value of defaultStr.

         StringUtils.defaultIfBlank(null, "NULL")  = "NULL"
         StringUtils.defaultIfBlank("", "NULL")    = "NULL"
         StringUtils.defaultIfBlank(" ", "NULL")   = "NULL"
         StringUtils.defaultIfBlank("bat", "NULL") = "bat"
         StringUtils.defaultIfBlank("", null)      = null
         
        Parameters:
        str - the String to check, may be null
        defaultStr - the default String to return if the input is whitespace, empty ("") or null, may be null
        Returns:
        the passed in String, or the default
        Since:
        2.6
        See Also:
        defaultString(String, String)
      • defaultIfEmpty

        public static String defaultIfEmpty​(String str,
                                            String defaultStr)

        Returns either the passed in String, or if the String is empty or null, the value of defaultStr.

         StringUtils.defaultIfEmpty(null, "NULL")  = "NULL"
         StringUtils.defaultIfEmpty("", "NULL")    = "NULL"
         StringUtils.defaultIfEmpty("bat", "NULL") = "bat"
         StringUtils.defaultIfEmpty("", null)      = null
         
        Parameters:
        str - the String to check, may be null
        defaultStr - the default String to return if the input is empty ("") or null, may be null
        Returns:
        the passed in String, or the default
        See Also:
        defaultString(String, String)
      • reverse

        public static String reverse​(String str)

        Reverses a String as per StrBuilder.reverse().

        A null String returns null.

         StringUtils.reverse(null)  = null
         StringUtils.reverse("")    = ""
         StringUtils.reverse("bat") = "tab"
         
        Parameters:
        str - the String to reverse, may be null
        Returns:
        the reversed String, null if null String input
      • reverseDelimited

        public static String reverseDelimited​(String str,
                                              char separatorChar)

        Reverses a String that is delimited by a specific character.

        The Strings between the delimiters are not reversed. Thus java.lang.String becomes String.lang.java (if the delimiter is '.').

         StringUtils.reverseDelimited(null, *)      = null
         StringUtils.reverseDelimited("", *)        = ""
         StringUtils.reverseDelimited("a.b.c", 'x') = "a.b.c"
         StringUtils.reverseDelimited("a.b.c", ".") = "c.b.a"
         
        Parameters:
        str - the String to reverse, may be null
        separatorChar - the separator character to use
        Returns:
        the reversed String, null if null String input
        Since:
        2.0
      • reverseDelimitedString

        public static String reverseDelimitedString​(String str,
                                                    String separatorChars)
        Deprecated.
        Use reverseDelimited(String, char) instead. This method is broken as the join doesn't know which char to use. Method will be removed in Commons Lang 3.0.

        Reverses a String that is delimited by a specific character.

        The Strings between the delimiters are not reversed. Thus java.lang.String becomes String.lang.java (if the delimiter is ".").

         StringUtils.reverseDelimitedString(null, *)       = null
         StringUtils.reverseDelimitedString("",*)          = ""
         StringUtils.reverseDelimitedString("a.b.c", null) = "a.b.c"
         StringUtils.reverseDelimitedString("a.b.c", ".")  = "c.b.a"
         
        Parameters:
        str - the String to reverse, may be null
        separatorChars - the separator characters to use, null treated as whitespace
        Returns:
        the reversed String, null if null String input
      • abbreviate

        public static String abbreviate​(String str,
                                        int maxWidth)

        Abbreviates a String using ellipses. This will turn "Now is the time for all good men" into "Now is the time for..."

        Specifically:

        • If str is less than maxWidth characters long, return it.
        • Else abbreviate it to (substring(str, 0, max-3) + "...").
        • If maxWidth is less than 4, throw an IllegalArgumentException.
        • In no case will it return a String of length greater than maxWidth.

         StringUtils.abbreviate(null, *)      = null
         StringUtils.abbreviate("", 4)        = ""
         StringUtils.abbreviate("abcdefg", 6) = "abc..."
         StringUtils.abbreviate("abcdefg", 7) = "abcdefg"
         StringUtils.abbreviate("abcdefg", 8) = "abcdefg"
         StringUtils.abbreviate("abcdefg", 4) = "a..."
         StringUtils.abbreviate("abcdefg", 3) = IllegalArgumentException
         
        Parameters:
        str - the String to check, may be null
        maxWidth - maximum length of result String, must be at least 4
        Returns:
        abbreviated String, null if null String input
        Throws:
        IllegalArgumentException - if the width is too small
        Since:
        2.0
      • abbreviate

        public static String abbreviate​(String str,
                                        int offset,
                                        int maxWidth)

        Abbreviates a String using ellipses. This will turn "Now is the time for all good men" into "...is the time for..."

        Works like abbreviate(String, int), but allows you to specify a "left edge" offset. Note that this left edge is not necessarily going to be the leftmost character in the result, or the first character following the ellipses, but it will appear somewhere in the result.

        In no case will it return a String of length greater than maxWidth.

         StringUtils.abbreviate(null, *, *)                = null
         StringUtils.abbreviate("", 0, 4)                  = ""
         StringUtils.abbreviate("abcdefghijklmno", -1, 10) = "abcdefg..."
         StringUtils.abbreviate("abcdefghijklmno", 0, 10)  = "abcdefg..."
         StringUtils.abbreviate("abcdefghijklmno", 1, 10)  = "abcdefg..."
         StringUtils.abbreviate("abcdefghijklmno", 4, 10)  = "abcdefg..."
         StringUtils.abbreviate("abcdefghijklmno", 5, 10)  = "...fghi..."
         StringUtils.abbreviate("abcdefghijklmno", 6, 10)  = "...ghij..."
         StringUtils.abbreviate("abcdefghijklmno", 8, 10)  = "...ijklmno"
         StringUtils.abbreviate("abcdefghijklmno", 10, 10) = "...ijklmno"
         StringUtils.abbreviate("abcdefghijklmno", 12, 10) = "...ijklmno"
         StringUtils.abbreviate("abcdefghij", 0, 3)        = IllegalArgumentException
         StringUtils.abbreviate("abcdefghij", 5, 6)        = IllegalArgumentException
         
        Parameters:
        str - the String to check, may be null
        offset - left edge of source String
        maxWidth - maximum length of result String, must be at least 4
        Returns:
        abbreviated String, null if null String input
        Throws:
        IllegalArgumentException - if the width is too small
        Since:
        2.0
      • abbreviateMiddle

        public static String abbreviateMiddle​(String str,
                                              String middle,
                                              int length)

        Abbreviates a String to the length passed, replacing the middle characters with the supplied replacement String.

        This abbreviation only occurs if the following criteria is met:

        • Neither the String for abbreviation nor the replacement String are null or empty
        • The length to truncate to is less than the length of the supplied String
        • The length to truncate to is greater than 0
        • The abbreviated String will have enough room for the length supplied replacement String and the first and last characters of the supplied String for abbreviation
        Otherwise, the returned String will be the same as the supplied String for abbreviation.

         StringUtils.abbreviateMiddle(null, null, 0)      = null
         StringUtils.abbreviateMiddle("abc", null, 0)      = "abc"
         StringUtils.abbreviateMiddle("abc", ".", 0)      = "abc"
         StringUtils.abbreviateMiddle("abc", ".", 3)      = "abc"
         StringUtils.abbreviateMiddle("abcdef", ".", 4)     = "ab.f"
         
        Parameters:
        str - the String to abbreviate, may be null
        middle - the String to replace the middle characters with, may be null
        length - the length to abbreviate str to.
        Returns:
        the abbreviated String if the above criteria is met, or the original String supplied for abbreviation.
        Since:
        2.5
      • difference

        public static String difference​(String str1,
                                        String str2)

        Compares two Strings, and returns the portion where they differ. (More precisely, return the remainder of the second String, starting from where it's different from the first.)

        For example, difference("i am a machine", "i am a robot") -> "robot".

         StringUtils.difference(null, null) = null
         StringUtils.difference("", "") = ""
         StringUtils.difference("", "abc") = "abc"
         StringUtils.difference("abc", "") = ""
         StringUtils.difference("abc", "abc") = ""
         StringUtils.difference("ab", "abxyz") = "xyz"
         StringUtils.difference("abcde", "abxyz") = "xyz"
         StringUtils.difference("abcde", "xyz") = "xyz"
         
        Parameters:
        str1 - the first String, may be null
        str2 - the second String, may be null
        Returns:
        the portion of str2 where it differs from str1; returns the empty String if they are equal
        Since:
        2.0
      • indexOfDifference

        public static int indexOfDifference​(String str1,
                                            String str2)

        Compares two Strings, and returns the index at which the Strings begin to differ.

        For example, indexOfDifference("i am a machine", "i am a robot") -> 7

         StringUtils.indexOfDifference(null, null) = -1
         StringUtils.indexOfDifference("", "") = -1
         StringUtils.indexOfDifference("", "abc") = 0
         StringUtils.indexOfDifference("abc", "") = 0
         StringUtils.indexOfDifference("abc", "abc") = -1
         StringUtils.indexOfDifference("ab", "abxyz") = 2
         StringUtils.indexOfDifference("abcde", "abxyz") = 2
         StringUtils.indexOfDifference("abcde", "xyz") = 0
         
        Parameters:
        str1 - the first String, may be null
        str2 - the second String, may be null
        Returns:
        the index where str2 and str1 begin to differ; -1 if they are equal
        Since:
        2.0
      • indexOfDifference

        public static int indexOfDifference​(String[] strs)

        Compares all Strings in an array and returns the index at which the Strings begin to differ.

        For example, indexOfDifference(new String[] {"i am a machine", "i am a robot"}) -> 7

         StringUtils.indexOfDifference(null) = -1
         StringUtils.indexOfDifference(new String[] {}) = -1
         StringUtils.indexOfDifference(new String[] {"abc"}) = -1
         StringUtils.indexOfDifference(new String[] {null, null}) = -1
         StringUtils.indexOfDifference(new String[] {"", ""}) = -1
         StringUtils.indexOfDifference(new String[] {"", null}) = 0
         StringUtils.indexOfDifference(new String[] {"abc", null, null}) = 0
         StringUtils.indexOfDifference(new String[] {null, null, "abc"}) = 0
         StringUtils.indexOfDifference(new String[] {"", "abc"}) = 0
         StringUtils.indexOfDifference(new String[] {"abc", ""}) = 0
         StringUtils.indexOfDifference(new String[] {"abc", "abc"}) = -1
         StringUtils.indexOfDifference(new String[] {"abc", "a"}) = 1
         StringUtils.indexOfDifference(new String[] {"ab", "abxyz"}) = 2
         StringUtils.indexOfDifference(new String[] {"abcde", "abxyz"}) = 2
         StringUtils.indexOfDifference(new String[] {"abcde", "xyz"}) = 0
         StringUtils.indexOfDifference(new String[] {"xyz", "abcde"}) = 0
         StringUtils.indexOfDifference(new String[] {"i am a machine", "i am a robot"}) = 7
         
        Parameters:
        strs - array of strings, entries may be null
        Returns:
        the index where the strings begin to differ; -1 if they are all equal
        Since:
        2.4
      • getCommonPrefix

        public static String getCommonPrefix​(String[] strs)

        Compares all Strings in an array and returns the initial sequence of characters that is common to all of them.

        For example, getCommonPrefix(new String[] {"i am a machine", "i am a robot"}) -> "i am a "

         StringUtils.getCommonPrefix(null) = ""
         StringUtils.getCommonPrefix(new String[] {}) = ""
         StringUtils.getCommonPrefix(new String[] {"abc"}) = "abc"
         StringUtils.getCommonPrefix(new String[] {null, null}) = ""
         StringUtils.getCommonPrefix(new String[] {"", ""}) = ""
         StringUtils.getCommonPrefix(new String[] {"", null}) = ""
         StringUtils.getCommonPrefix(new String[] {"abc", null, null}) = ""
         StringUtils.getCommonPrefix(new String[] {null, null, "abc"}) = ""
         StringUtils.getCommonPrefix(new String[] {"", "abc"}) = ""
         StringUtils.getCommonPrefix(new String[] {"abc", ""}) = ""
         StringUtils.getCommonPrefix(new String[] {"abc", "abc"}) = "abc"
         StringUtils.getCommonPrefix(new String[] {"abc", "a"}) = "a"
         StringUtils.getCommonPrefix(new String[] {"ab", "abxyz"}) = "ab"
         StringUtils.getCommonPrefix(new String[] {"abcde", "abxyz"}) = "ab"
         StringUtils.getCommonPrefix(new String[] {"abcde", "xyz"}) = ""
         StringUtils.getCommonPrefix(new String[] {"xyz", "abcde"}) = ""
         StringUtils.getCommonPrefix(new String[] {"i am a machine", "i am a robot"}) = "i am a "
         
        Parameters:
        strs - array of String objects, entries may be null
        Returns:
        the initial sequence of characters that are common to all Strings in the array; empty String if the array is null, the elements are all null or if there is no common prefix.
        Since:
        2.4
      • getLevenshteinDistance

        public static int getLevenshteinDistance​(String s,
                                                 String t)

        Find the Levenshtein distance between two Strings.

        This is the number of changes needed to change one String into another, where each change is a single character modification (deletion, insertion or substitution).

        The previous implementation of the Levenshtein distance algorithm was from http://www.merriampark.com/ld.htm

        Chas Emerick has written an implementation in Java, which avoids an OutOfMemoryError which can occur when my Java implementation is used with very large strings.
        This implementation of the Levenshtein distance algorithm is from http://www.merriampark.com/ldjava.htm

         StringUtils.getLevenshteinDistance(null, *)             = IllegalArgumentException
         StringUtils.getLevenshteinDistance(*, null)             = IllegalArgumentException
         StringUtils.getLevenshteinDistance("","")               = 0
         StringUtils.getLevenshteinDistance("","a")              = 1
         StringUtils.getLevenshteinDistance("aaapppp", "")       = 7
         StringUtils.getLevenshteinDistance("frog", "fog")       = 1
         StringUtils.getLevenshteinDistance("fly", "ant")        = 3
         StringUtils.getLevenshteinDistance("elephant", "hippo") = 7
         StringUtils.getLevenshteinDistance("hippo", "elephant") = 7
         StringUtils.getLevenshteinDistance("hippo", "zzzzzzzz") = 8
         StringUtils.getLevenshteinDistance("hello", "hallo")    = 1
         
        Parameters:
        s - the first String, must not be null
        t - the second String, must not be null
        Returns:
        result distance
        Throws:
        IllegalArgumentException - if either String input null
      • startsWith

        public static boolean startsWith​(String str,
                                         String prefix)

        Check if a String starts with a specified prefix.

        nulls are handled without exceptions. Two null references are considered to be equal. The comparison is case sensitive.

         StringUtils.startsWith(null, null)      = true
         StringUtils.startsWith(null, "abc")     = false
         StringUtils.startsWith("abcdef", null)  = false
         StringUtils.startsWith("abcdef", "abc") = true
         StringUtils.startsWith("ABCDEF", "abc") = false
         
        Parameters:
        str - the String to check, may be null
        prefix - the prefix to find, may be null
        Returns:
        true if the String starts with the prefix, case sensitive, or both null
        Since:
        2.4
        See Also:
        String.startsWith(String)
      • startsWithIgnoreCase

        public static boolean startsWithIgnoreCase​(String str,
                                                   String prefix)

        Case insensitive check if a String starts with a specified prefix.

        nulls are handled without exceptions. Two null references are considered to be equal. The comparison is case insensitive.

         StringUtils.startsWithIgnoreCase(null, null)      = true
         StringUtils.startsWithIgnoreCase(null, "abc")     = false
         StringUtils.startsWithIgnoreCase("abcdef", null)  = false
         StringUtils.startsWithIgnoreCase("abcdef", "abc") = true
         StringUtils.startsWithIgnoreCase("ABCDEF", "abc") = true
         
        Parameters:
        str - the String to check, may be null
        prefix - the prefix to find, may be null
        Returns:
        true if the String starts with the prefix, case insensitive, or both null
        Since:
        2.4
        See Also:
        String.startsWith(String)
      • startsWithAny

        public static boolean startsWithAny​(String string,
                                            String[] searchStrings)

        Check if a String starts with any of an array of specified strings.

         StringUtils.startsWithAny(null, null)      = false
         StringUtils.startsWithAny(null, new String[] {"abc"})  = false
         StringUtils.startsWithAny("abcxyz", null)     = false
         StringUtils.startsWithAny("abcxyz", new String[] {""}) = false
         StringUtils.startsWithAny("abcxyz", new String[] {"abc"}) = true
         StringUtils.startsWithAny("abcxyz", new String[] {null, "xyz", "abc"}) = true
         
        Parameters:
        string - the String to check, may be null
        searchStrings - the Strings to find, may be null or empty
        Returns:
        true if the String starts with any of the the prefixes, case insensitive, or both null
        Since:
        2.5
        See Also:
        startsWith(String, String)
      • endsWith

        public static boolean endsWith​(String str,
                                       String suffix)

        Check if a String ends with a specified suffix.

        nulls are handled without exceptions. Two null references are considered to be equal. The comparison is case sensitive.

         StringUtils.endsWith(null, null)      = true
         StringUtils.endsWith(null, "def")     = false
         StringUtils.endsWith("abcdef", null)  = false
         StringUtils.endsWith("abcdef", "def") = true
         StringUtils.endsWith("ABCDEF", "def") = false
         StringUtils.endsWith("ABCDEF", "cde") = false
         
        Parameters:
        str - the String to check, may be null
        suffix - the suffix to find, may be null
        Returns:
        true if the String ends with the suffix, case sensitive, or both null
        Since:
        2.4
        See Also:
        String.endsWith(String)
      • endsWithIgnoreCase

        public static boolean endsWithIgnoreCase​(String str,
                                                 String suffix)

        Case insensitive check if a String ends with a specified suffix.

        nulls are handled without exceptions. Two null references are considered to be equal. The comparison is case insensitive.

         StringUtils.endsWithIgnoreCase(null, null)      = true
         StringUtils.endsWithIgnoreCase(null, "def")     = false
         StringUtils.endsWithIgnoreCase("abcdef", null)  = false
         StringUtils.endsWithIgnoreCase("abcdef", "def") = true
         StringUtils.endsWithIgnoreCase("ABCDEF", "def") = true
         StringUtils.endsWithIgnoreCase("ABCDEF", "cde") = false
         
        Parameters:
        str - the String to check, may be null
        suffix - the suffix to find, may be null
        Returns:
        true if the String ends with the suffix, case insensitive, or both null
        Since:
        2.4
        See Also:
        String.endsWith(String)
      • normalizeSpace

        public static String normalizeSpace​(String str)

        Similar to http://www.w3.org/TR/xpath/#function-normalize -space

        The function returns the argument string with whitespace normalized by using trim(String) to remove leading and trailing whitespace and then replacing sequences of whitespace characters by a single space.

        In XML Whitespace characters are the same as those allowed by the S production, which is S ::= (#x20 | #x9 | #xD | #xA)+

        See Java's Character.isWhitespace(char) for which characters are considered whitespace.

        The difference is that Java's whitespace includes vertical tab and form feed, which this functional will also normalize. Additonally trim(String) removes control characters (char <= 32) from both ends of this String.

        Parameters:
        str - the source String to normalize whitespaces from, may be null
        Returns:
        the modified string with whitespace normalized, null if null String input
        Since:
        2.6
        See Also:
        Character.isWhitespace(char), trim(String), http://www.w3.org/TR/xpath/#function-normalize-space
      • endsWithAny

        public static boolean endsWithAny​(String string,
                                          String[] searchStrings)

        Check if a String ends with any of an array of specified strings.

         StringUtils.endsWithAny(null, null)      = false
         StringUtils.endsWithAny(null, new String[] {"abc"})  = false
         StringUtils.endsWithAny("abcxyz", null)     = false
         StringUtils.endsWithAny("abcxyz", new String[] {""}) = true
         StringUtils.endsWithAny("abcxyz", new String[] {"xyz"}) = true
         StringUtils.endsWithAny("abcxyz", new String[] {null, "xyz", "abc"}) = true
         
        Parameters:
        string - the String to check, may be null
        searchStrings - the Strings to find, may be null or empty
        Returns:
        true if the String ends with any of the the prefixes, case insensitive, or both null
        Since:
        2.6