Class SimplifyBooleanReturnCheck

  • All Implemented Interfaces:
    Configurable, Contextualizable

    public class SimplifyBooleanReturnCheck
    extends AbstractCheck

    Checks for over-complicated boolean return statements. For example the following code

     if (valid())
       return false;
     else
       return true;
     

    could be written as

     return !valid();
     

    The idea for this Check has been shamelessly stolen from the equivalent PMD rule.

    To configure the check:

     <module name="SimplifyBooleanReturn"/>
     

    Example:

     public class Test {
    
      private boolean cond;
      private Foo a;
      private Foo b;
    
      public boolean check1() {
       if (cond) { // violation, can be simplified
         return true;
       }
       else {
         return false;
       }
      }
    
      // Ok, simplified version of check1()
      public boolean check2() {
       return cond;
      }
    
      // violations, can be simplified
      public boolean check3() {
       if (cond == true) { // can be simplified to "if (cond)"
         return false;
       }
       else {
         return true; // can be simplified to "return !cond"
       }
      }
    
      // Ok, can be simplified but doesn't return a Boolean
      public Foo choose1() {
       if (cond) {
         return a;
       }
       else {
         return b;
       }
      }
    
      // Ok, simplified version of choose1()
      public Foo choose2() {
       return cond ? a: b;
      }
    
     }
     

    Parent is com.puppycrawl.tools.checkstyle.TreeWalker

    Violation Message Keys:

    • simplify.boolReturn
    Since:
    3.0
    • Method Detail

      • 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
      • canReturnOnlyBooleanLiteral

        private static boolean canReturnOnlyBooleanLiteral​(DetailAST ast)
        Returns if an AST is a return statement with a boolean literal or a compound statement that contains only such a return statement.

        Returns true iff ast represents

         return true/false;
         
        or
         {
           return true/false;
         }
         
        Parameters:
        ast - the syntax tree to check
        Returns:
        if ast is a return statement with a boolean literal.
      • isBooleanLiteralReturnStatement

        private static boolean isBooleanLiteralReturnStatement​(DetailAST ast)
        Returns if an AST is a return statement with a boolean literal.

        Returns true iff ast represents

         return true/false;
         
        Parameters:
        ast - the syntax tree to check
        Returns:
        if ast is a return statement with a boolean literal.