Package com.puppycrawl.tools.checkstyle.checks.coding

Class FinalLocalVariableCheck

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

    Checks that local variables that never have their values changed are declared final. The check can be configured to also check that unchanged parameters are declared final.

    When configured to check parameters, the check ignores parameters of interface methods and abstract methods.

    • Property validateEnhancedForLoopVariable - Control whether to check enhanced for-loop variable. Type is boolean. Default value is false.
    • Property tokens - tokens to check Type is java.lang.String[]. Validation type is tokenSet. Default value is: VARIABLE_DEF.

    To configure the check: 

     <module name="FinalLocalVariable"/>

    To configure the check so that it checks local variables and parameters: 

     <module name="FinalLocalVariable">
   <property name="tokens" value="VARIABLE_DEF,PARAMETER_DEF"/>
 </module>

    By default, this Check skip final validation on Enhanced For-Loop.

    Option 'validateEnhancedForLoopVariable' could be used to make Check to validate even variable from Enhanced For Loop.

    An example of how to configure the check so that it also validates enhanced For Loop Variable is: 

     <module name="FinalLocalVariable">
   <property name="tokens" value="VARIABLE_DEF"/>
   <property name="validateEnhancedForLoopVariable" value="true"/>
 </module>

    Example:

     for (int number : myNumbers) { // violation
   System.out.println(number);
 }

    An example of how to configure check on local variables and parameters but do not validate loop variables: 

     <module name="FinalLocalVariable">
    <property name="tokens" value="VARIABLE_DEF,PARAMETER_DEF"/>
    <property name="validateEnhancedForLoopVariable" value="false"/>
  </module>

    Example: 

     public class MyClass {
   static int foo(int x, int y) { //violations, parameters should be final
     return x+y;
   }
   public static void main (String []args) { //violation, parameters should be final
     for (String i : args) {
       System.out.println(i);
     }
     int result=foo(1,2); // violation
   }
 }

    Parent is com.puppycrawl.tools.checkstyle.TreeWalker

    Violation Message Keys:

    • final.variable
    Since:
    3.2

    • 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

      • FinalLocalVariableCheck

        public FinalLocalVariableCheck()

    • Method Detail

      • setValidateEnhancedForLoopVariable

        public final void setValidateEnhancedForLoopVariable​(boolean validateEnhancedForLoopVariable)
        Setter to control whether to check enhanced for-loop variable.
        Parameters:
        validateEnhancedForLoopVariable - whether to check for-loop variable

      • 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

      • 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

      • leaveToken

        public void leaveToken​(DetailAST ast)
        Description copied from class: AbstractCheck
        Called after all the child nodes have been process.
        Overrides:
        leaveToken in class AbstractCheck
        Parameters:
        ast - the token leaving