[COLLECTIONS-331] CollatingIterator NPE when Comparator is null

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 3.2
• Fix Version/s: 4.0-alpha1, 4.0
• Component/s: Iterator
• Assignee: Jochen Wiedmann
• Reporter: Michael Krkoska
• Created: 24/Jun/09 14:32
• Updated: 09/Nov/14 14:31
• Resolved: 08/Mar/11 22:33

Description

Run the attached Test against commons-collections-3.2.1. While the JavaDoc for CollatingIterator claims

@param comp the comparator to use to sort, or null to use natural sort order

the test fails, because the comparator is null.

Fixing this requires a change in org.apache.commons.collections.iterators.CollatingIterator.least():

if (comparator.compare(curObject,leastObject) < 0) { ...

could be replaced with

int c = comparator==null?((Comparable)curObject).compareTo(leastObject):comparator.compare(curObject,leastObject);
if (c < 0) { ...

The workaround is to provide a comparator, of course.