[jira] [Resolved] (COLLECTIONS-514) NullPointerException in MapBackedSet.mapBackedSet

["Thomas Neidhart (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/COLLECTIONS-514?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Thomas Neidhart resolved COLLECTIONS-514.
-----------------------------------------

    Resolution: Invalid

The use TreeBag states that it uses a TreeMap as underlying data structure, this the same limitations apply as for a TreeMap.

In fact I consider this even a bug in the jdk, as the TreeMap states that adding a mapping with a null key and natural ordering will result in a NullPointerException, although it does not immediately, only when you try to get the entry with a null key:

{noformat}
        SortedMap<String, String> map = new TreeMap<String, String>();
        map.put(null, null);
        System.out.println(map.get(null));
{noformat}

The NullPointerException is only thrown in the call to get().

> NullPointerException in MapBackedSet.mapBackedSet
> -------------------------------------------------
>
>                 Key: COLLECTIONS-514
>                 URL: https://issues.apache.org/jira/browse/COLLECTIONS-514
>             Project: Commons Collections
>          Issue Type: Bug
>          Components: Bag, Collection, Set
>    Affects Versions: 4.0
>         Environment: MacOS 10.9, Java 6
>            Reporter: Cyrille Artho
>         Attachments: Report2.java
>
>
> It seems that addAll has issues with adding a set that is backed by a singleton map with entry null -> null. However, the javadoc of the involved classes does not state that null entries are disallowed.
> Either the code should allow adding a null entry to a bag, or the documentation should state that null entries are not allowed.
> See the attached unit test in JUnit format to reproduce the problem.



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