Class SimplifyBooleanReturnCheck

java.lang.Object
com.puppycrawl.tools.checkstyle.api.AutomaticBean
com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter
com.puppycrawl.tools.checkstyle.api.AbstractCheck
com.puppycrawl.tools.checkstyle.checks.coding.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

  • 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

    • SimplifyBooleanReturnCheck

      public SimplifyBooleanReturnCheck()

  • Method Details

    • 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:

    • 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:

    • 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:

    • 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

    • 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.