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

Class SimplifyBooleanExpressionCheck

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.SimplifyBooleanExpressionCheck
All Implemented Interfaces:
Configurable, Contextualizable
public class SimplifyBooleanExpressionCheck extends AbstractCheck

Checks for over-complicated boolean expressions. Currently finds code like if (b == true), b || true, !false, boolean a = q > 12 ? true : false, etc.

Rationale: Complex boolean logic makes code hard to understand and maintain.

To configure the check: 

 <module name="SimplifyBooleanExpression"/>

Example:

 public class Test {

   public void bar() {

     boolean a, b;
     Foo c, d, e;

     if (!false) {};       // violation, can be simplified to true

     if (a == true) {};    // violation, can be simplified to a
     if (a == b) {};       // OK
     if (a == false) {};   // violation, can be simplified to !a
     if (!(a != true)) {}; // violation, can be simplified to a

     e = (a || b) ? c : d;     // OK
     e = (a || false) ? c : d; // violation, can be simplified to a
     e = (a && b) ? c : d;     // OK

     int s = 12;
     boolean m = s > 1 ? true : false; // violation, can be simplified to s > 1
     boolean f = c == null ? false : c.someMethod(); // OK
  }

 }

Parent is com.puppycrawl.tools.checkstyle.TreeWalker

Violation Message Keys:

  • simplify.expression
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

    • SimplifyBooleanExpressionCheck

      public SimplifyBooleanExpressionCheck()

  • Method Details

    • 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:

    • 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