WhitespaceAround.md

Pattern: Malformed whitespace around token

Issue: -

Description

Checks that a token is surrounded by whitespace. Empty constructor, method, class, enum, interface, loop bodies (blocks), lambdas of the form

public MyClass() {}      // empty constructor
public void func() {}    // empty method
public interface Foo {} // empty interface
public class Foo {} // empty class
public enum Foo {} // empty enum
MyClass c = new MyClass() {}; // empty anonymous class
while (i = 1) {} // empty while loop
for (int i = 1; i > 1; i++) {} // empty for loop
do {} while (i = 1); // empty do-while loop
Runnable noop = () -> {}; // empty lambda
public @interface Beta {} // empty annotation type

may optionally be exempted from the policy using the allowEmptyMethods, allowEmptyConstructors , allowEmptyTypes, allowEmptyLoops allowEmptyLambdas and allowEmptyCatches properties.

This check does not flag as violation double brace initialization like:

new Properties() {{
    setProperty("key", "value");
}};

Parameter allowEmptyCatches allows to suppress violations when token list contains SLIST to check if beginning of block is surrounded by whitespace and catch block is empty, for example:

try {
    k = 5 / i;
} catch (ArithmeticException ex) {}

With this property turned off, this raises violation because the beginning of the catch block (left curly bracket) is not separated from the end of the catch block (right curly bracket).

Examples

To configure the check:

<module name="WhitespaceAround"/>

To configure the check for whitespace around the assignment operator, =:

<module name="WhitespaceAround">
    <property name="tokens" value="ASSIGN"/>
</module>

Further Reading

• checkstyle - WhitespaceAround