Description

Rationale: Too many conditions leads to code that is difficult to read and hence debug and maintain.

Note that the operators & and | are not only integer bitwise operators, they are also the non-shortcut versions of the boolean operators && and ||.

Note that &, | and ^ are not checked if they are part of constructor or method call because they can be applied to non-boolean variables and Checkstyle does not know types of methods from different classes.

Properties

Examples

To configure the check:

<module name="Checker">
  <module name="TreeWalker">
    <module name="BooleanExpressionComplexity"/>
  </module>
</module>
        

Code Example:

public class Example1
{
  public static void main(String ... args)
  {
    boolean a = true;
    boolean b = false;

    boolean c = (a & b) | (b ^ a); // OK, 1(&) + 1(|) + 1(^) = 3 (max allowed 3)

    boolean d = (a & b) | (b ^ a) | (a ^ b);
    // violation above, 'Boolean expression complexity is 5 (max allowed is 3)'
    // 1(&) + 1(|) + 1(^) + 1(|) + 1(^) = 5

    boolean e = a ^ (a || b) ^ (b || a) & (a | b);
    // violation above, 'Boolean expression complexity is 6 (max allowed is 3)'
    // 1(^) + 1(||) + 1(^) + 1(||) + 1(&) + 1(|) = 6
  }
}
        

To configure the check with 5 allowed operation in boolean expression:

<module name="Checker">
  <module name="TreeWalker">
    <module name="BooleanExpressionComplexity">
      <property name="max" value="5"/>
    </module>
  </module>
</module>
        

Code Example:

public class Example2
{
  public static void main(String ... args)
  {
    boolean a = true;
    boolean b = false;

    boolean c = (a & b) | (b ^ a); // OK, 1(&) + 1(|) + 1(^) = 3 (max allowed 5)

    boolean d = (a & b) | (b ^ a) | (a ^ b);
    // OK above, 1(&) + 1(|) + 1(^) + 1(|) + 1(^) = 5

    boolean e = a ^ (a || b) ^ (b || a) & (a | b);
    // violation above, 'Boolean expression complexity is 6 (max allowed is 5)'
    // 1(^) + 1(||) + 1(^) + 1(||) + 1(&) + 1(|) = 6
  }
}
        

To configure the check to ignore & and |:

<module name="Checker">
  <module name="TreeWalker">
    <module name="BooleanExpressionComplexity">
      <property name="tokens" value="BXOR,LAND,LOR"/>
    </module>
  </module>
</module>
        

Code Example:

public class Example3
{
  public static void main(String ... args)
  {
    boolean a = true;
    boolean b = false;

    boolean c = (a & b) | (b ^ a); // OK, 1(^) = 1 (max allowed 3)

    boolean d = (a & b) | (b ^ a) | (a ^ b);
    // OK above, 1(^) + 1(^) = 2, & and | are ignored here

    boolean e = a ^ (a || b) ^ (b || a) & (a | b);
    // violation above, 'Boolean expression complexity is 4 (max allowed is 3)'
    // 1(^) + 1(||) + 1(^) + 1(||) = 4, & and | are ignored here
  }
}
        

Example of Usage

• Checkstyle Style

Violation Messages

• booleanExpressionComplexity

All messages can be customized if the default message doesn't suit you. Please see the documentation to learn how to.

Package

com.puppycrawl.tools.checkstyle.checks.metrics

Parent Module

TreeWalker