Package com.puppycrawl.tools.checkstyle.checks

Class AvoidEscapedUnicodeCharactersCheck

  • All Implemented Interfaces:
    Configurable, Contextualizable
    public class AvoidEscapedUnicodeCharactersCheck
extends AbstractCheck

    Restricts using Unicode escapes (such as \u221e). It is possible to allow using escapes for non-printable, control characters. Also, this check can be configured to allow using escapes if trail comment is present. By the option it is possible to allow using escapes if literal contains only them.

    • Property allowEscapesForControlCharacters - Allow use escapes for non-printable, control characters. Type is boolean. Default value is false.
    • Property allowByTailComment - Allow use escapes if trail comment is present. Type is boolean. Default value is false.
    • Property allowIfAllCharactersEscaped - Allow if all characters in literal are escaped. Type is boolean. Default value is false.
    • Property allowNonPrintableEscapes - Allow use escapes for non-printable, whitespace characters. Type is boolean. Default value is false.

    To configure the check: 

     <module name="AvoidEscapedUnicodeCharacters"/>

    Examples of using Unicode:

     String unitAbbrev = "μs";      // Best: perfectly clear even without a comment.
 String unitAbbrev = "\u03bcs"; // Poor: the reader has no idea what this is.

    An example of non-printable, control characters. 

     return '\ufeff' + content; // byte order mark

    An example of how to configure the check to allow using escapes for non-printable, control characters: 

     <module name="AvoidEscapedUnicodeCharacters">
   <property name="allowEscapesForControlCharacters" value="true"/>
 </module>

    Example of using escapes with trail comment: 

     String unitAbbrev = "\u03bcs"; // Greek letter mu, "s"
 String textBlockUnitAbbrev = """
          \u03bcs"""; // Greek letter mu, "s"

    An example of how to configure the check to allow using escapes if trail comment is present: 

     <module name="AvoidEscapedUnicodeCharacters">
   <property name="allowByTailComment" value="true"/>
 </module>

    Example of using escapes if literal contains only them: 

     String unitAbbrev = "\u03bc\u03bc\u03bc";

    An example of how to configure the check to allow escapes if literal contains only them: 

     <module name="AvoidEscapedUnicodeCharacters">
   <property name="allowIfAllCharactersEscaped" value="true"/>
 </module>

    An example of how to configure the check to allow using escapes for non-printable, whitespace characters: 

     <module name="AvoidEscapedUnicodeCharacters">
   <property name="allowNonPrintableEscapes" value="true"/>
 </module>

    Parent is com.puppycrawl.tools.checkstyle.TreeWalker

    Violation Message Keys:

    • forbid.escaped.unicode.char
    Since:
    5.8

    • Field Detail

      • MSG_KEY

        public static final java.lang.String MSG_KEY
        A key is pointing to the warning message text in "messages.properties" file.
        See Also:
        Constant Field Values

    • Constructor Detail

      • AvoidEscapedUnicodeCharactersCheck

        public AvoidEscapedUnicodeCharactersCheck()

    • Method Detail

      • setAllowEscapesForControlCharacters

        public final void setAllowEscapesForControlCharacters​(boolean allow)
        Setter to allow use escapes for non-printable, control characters.
        Parameters:
        allow - user's value.

      • setAllowByTailComment

        public final void setAllowByTailComment​(boolean allow)
        Setter to allow use escapes if trail comment is present.
        Parameters:
        allow - user's value.

      • setAllowIfAllCharactersEscaped

        public final void setAllowIfAllCharactersEscaped​(boolean allow)
        Setter to allow if all characters in literal are escaped.
        Parameters:
        allow - user's value.

      • setAllowNonPrintableEscapes

        public final void setAllowNonPrintableEscapes​(boolean allow)
        Setter to allow use escapes for non-printable, whitespace characters.
        Parameters:
        allow - user's value.

      • getDefaultTokens

        public int[] getDefaultTokens()
        Description copied from class: AbstractCheck
        Returns the default token a check is interested in. Only used if the configuration for a check does not define the tokens.
        Specified by:
        getDefaultTokens in class AbstractCheck
        Returns:
        the default tokens
        See Also:
        TokenTypes

      • getAcceptableTokens

        public int[] getAcceptableTokens()
        Description copied from class: AbstractCheck
        The configurable token set. Used to protect Checks against malicious users who specify an unacceptable token set in the configuration file. The default implementation returns the check's default tokens.
        Specified by:
        getAcceptableTokens in class AbstractCheck
        Returns:
        the token set this check is designed for.
        See Also:
        TokenTypes

      • getRequiredTokens

        public int[] getRequiredTokens()
        Description copied from class: AbstractCheck
        The tokens that this check must be registered for.
        Specified by:
        getRequiredTokens in class AbstractCheck
        Returns:
        the token set this must be registered for.
        See Also:
        TokenTypes

      • beginTree

        public void beginTree​(DetailAST rootAST)
        Description copied from class: AbstractCheck
        Called before the starting to process a tree. Ideal place to initialize information that is to be collected whilst processing a tree.
        Overrides:
        beginTree in class AbstractCheck
        Parameters:
        rootAST - the root of the tree