Package com.puppycrawl.tools.checkstyle.checks.naming

Class LocalVariableNameCheck

  • All Implemented Interfaces:
    Configurable, Contextualizable
    public class LocalVariableNameCheck
extends AbstractNameCheck

    Checks that local, non-final variable names conform to a specified pattern. A catch parameter is considered to be a local variable.

    • Property format - Specifies valid identifiers. Type is java.util.regex.Pattern. Default value is "^[a-z][a-zA-Z0-9]*$".
    • Property allowOneCharVarInForLoop - Allow one character variable name in initialization expressions in FOR loop if one char variable name is prohibited by format regexp. Type is boolean. Default value is false.

    To configure the check: 

     <module name="LocalVariableName"/>

    Code Example:

     class MyClass {
   void MyMethod() {
     for (int var = 1; var < 10; var++) {} // OK
     for (int VAR = 1; VAR < 10; VAR++) {} // violation, name 'VAR' must match
                                           // pattern '^[a-z][a-zA-Z0-9]*$'
     for (int i = 1; i < 10; i++) {} // OK
     for (int var_1 = 0; var_1 < 10; var_1++) {} // violation, name 'var_1' must match
                                                    // pattern '^[a-z][a-zA-Z0-9]*$'
   }
 }

    An example of how to configure the check for names that begin with a lower case letter, followed by letters, digits, and underscores is: 

     <module name="LocalVariableName">
   <property name="format" value="^[a-z](_?[a-zA-Z0-9]+)*$"/>
 </module>

    Code Example:

     class MyClass {
   void MyMethod() {
     for (int var = 1; var < 10; var++) {} // OK
     for (int VAR = 1; VAR < 10; VAR++) {} // violation, name 'VAR' must match
                                              // pattern '^[a-z](_?[a-zA-Z0-9]+)*$'
     for (int i = 1; i < 10; i++) {} // OK
     for (int var_1 = 0; var_1 < 10; var_1++) {} // OK
   }
 }

    An example of one character variable name in initialization expression(like "i") in FOR loop: 

     for(int i = 1; i < 10; i++) {}
 for(int K = 1; K < 10; K++) {}
 List list = new ArrayList();
 for (Object o : list) {}
 for (Object O : list) {}

    An example of how to configure the check to allow one character variable name in initialization expressions in FOR loop, where regexp allows 2 or more chars: 

     <module name="LocalVariableName">
   <property name="format" value="^[a-z][_a-zA-Z0-9]+$"/>
   <property name="allowOneCharVarInForLoop" value="true"/>
 </module>

    Code Example:

     class MyClass {
   void MyMethod() {
     int good = 1;
     int g = 0; // violation
     for (int v = 1; v < 10; v++) { // OK
         int a = 1; // violation
     }
     for (int V = 1; V < 10; V++) { // OK
         int I = 1; // violation
     }
     List list = new ArrayList();
     for (Object o : list) { // OK
         String a = ""; // violation
     }
     for (Object O : list) { // OK
         String A = ""; // violation
     }
   }
 }

    An example of how to configure the check to that all variables have 3 or more chars in name: 

     <module name="LocalVariableName">
   <property name="format" value="^[a-z][_a-zA-Z0-9]{2,}$"/>
 </module>

    Code Example:

     class MyClass {
   void MyMethod() {
     int goodName = 0;
     int i = 1; // violation
     for (int var = 1; var < 10; var++) { //OK
       int j = 1; // violation
     }
   }
 }

    Parent is com.puppycrawl.tools.checkstyle.TreeWalker

    Violation Message Keys:

    • name.invalidPattern
    Since:
    3.0

    • Constructor Detail

      • LocalVariableNameCheck

        public LocalVariableNameCheck()
        Creates a new LocalVariableNameCheck instance.

    • Method Detail

      • setAllowOneCharVarInForLoop

        public final void setAllowOneCharVarInForLoop​(boolean allow)
        Setter to allow one character variable name in initialization expressions in FOR loop if one char variable name is prohibited by format regexp.
        Parameters:
        allow - Flag for allowing or not one character name in FOR loop.

      • 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

      • mustCheckName

        protected final boolean mustCheckName​(DetailAST ast)
        Description copied from class: AbstractNameCheck
        Decides whether the name of an AST should be checked against the format regexp.
        Specified by:
        mustCheckName in class AbstractNameCheck
        Parameters:
        ast - the AST to check.
        Returns:
        true if the IDENT subnode of ast should be checked against the format regexp.