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From "Thomas Neidhart (JIRA)" <j...@apache.org>
Subject [jira] [Resolved] (COLLECTIONS-377) CollatingIterator throws NullPointerException when constructor is given null (or no) Comparator
Date Sun, 03 Jun 2012 11:21:23 GMT

     [ https://issues.apache.org/jira/browse/COLLECTIONS-377?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Thomas Neidhart resolved COLLECTIONS-377.
-----------------------------------------

       Resolution: Duplicate
    Fix Version/s: 4.0

This has been fixed as part of [COLLECTIONS-331]. Now the javadoc states that a comparator
*must* be provided (either via constructor or by calling setComparator afterwards) before
using the iterator.
                
> CollatingIterator throws NullPointerException when constructor is given null (or no)
Comparator
> -----------------------------------------------------------------------------------------------
>
>                 Key: COLLECTIONS-377
>                 URL: https://issues.apache.org/jira/browse/COLLECTIONS-377
>             Project: Commons Collections
>          Issue Type: Bug
>          Components: Iterator
>    Affects Versions: 3.2
>         Environment: Java 1.6.0_26
>            Reporter: Ryan Hochstetler
>            Priority: Minor
>             Fix For: 4.0
>
>
> CollatingIterator's javadoc (http://commons.apache.org/collections/api-release/index.html)
states that natural sort ordering will be used when null is passed as the Comparator argument
to any of the constructors accepting one (and for the nullary constructor).  The following
stack is thrown from the subsequent unit test.  The implementation of least() does not appear
to account for the natural sort order case.
> java.lang.NullPointerException
> 	at org.apache.commons.collections.iterators.CollatingIterator.least(CollatingIterator.java:334)
> 	at org.apache.commons.collections.iterators.CollatingIterator.next(CollatingIterator.java:230)
> 	at mil.af.statistics.jutl.collection.MutableDataSeriesTest...
>     @SuppressWarnings("unchecked")
>     @Test
>     public void testCollatingIteratorNaturalOrdering() throws Exception
>     {
>         Integer[] expected =
>         { Integer.valueOf(1), Integer.valueOf(2), Integer.valueOf(3), Integer.valueOf(4),
Integer.valueOf(5),
>             Integer.valueOf(6) };
>         List<Integer> evens = Arrays.asList(new Integer[]
>         { Integer.valueOf(2), Integer.valueOf(4), Integer.valueOf(6) });
>         List<Integer> odds = Arrays.asList(new Integer[]
>         { Integer.valueOf(1), Integer.valueOf(3), Integer.valueOf(5) });
>         Iterator<Integer> collatingIter = new CollatingIterator(null, evens.iterator(),
odds.iterator());
>         for (Integer expectedInt : expected)
>         {
>             assertTrue(collatingIter.hasNext());
>             assertEquals(expectedInt, collatingIter.next());
>         }
>     }
> Workaround: provide a Comparator that implements the natural ordering contract.

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