[COLLECTIONS-814] CollectionUtils.removeAll() not throwing proper NullPointerException(NPE) if the first parameter is empty

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 4.4
• Fix Version/s: 4.5.0-M1
• Assignee: Bruno P. Kinoshita
• Reporter: Elia Bertolina
• Created: 23/May/22 07:43
• Updated: 19/Oct/22 02:13
• Resolved: 19/Oct/22 02:13

Description

The CollectionUtils.removeAll(Collection<E> collection, Collection<?> remove) does not throw a NullPointerException(NPE) when the “remove” parameters is null, but only if the “collection” parameter is empty.

In the documentation it is stated that an NPE will be thrown if any of the parameters is null.

However, in this test case:

 

public class CollectionUtils_failure_Test {
    public void test() throws Throwable {
        LinkedList<InstanceofPredicate> linkedList = new
        LinkedList<InstanceofPredicate>();
        try {
            Collection<InstanceofPredicate> collection =
            CollectionUtils.removeAll(
            (Collection<InstanceofPredicate>)linkedList,
            (Collection<?>) null);
            org.junit.Assert.fail();
        } catch (java.lang.NullPointerException e) {
           //Exception caught and test successful
        }    
    }
} 

 

This is a special case (first parameter needs to be empty and the second needs to be null) but this behavior is missing in the documentation. While this behavior is somehow correct (removing a null Object from an empty Collection we should obtain an empty Collection) I think throwing an NPE would be more in line with the documentation provided.