BooleanExpressionComplexity
Since Checkstyle 3.4
Description
&&, ||,
&, | and ^) in an expression.
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
Violation Messages
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