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 Details

    • MSG_KEY

      public static final String MSG_KEY
      A key is pointing to the warning message text in "messages.properties" file.
      See Also:
  • Constructor Details

    • FinalLocalVariableCheck

      public FinalLocalVariableCheck()
  • Method Details

    • 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:
    • 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:
    • 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:
    • visitToken

      public void visitToken(DetailAST ast)
      Description copied from class: AbstractCheck
      Called to process a token.
      Overrides:
      visitToken in class AbstractCheck
      Parameters:
      ast - the token to process
    • 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