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https://issues.apache.org/jira/browse/COLLECTIONS-424?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13446373#comment-13446373
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srirangadeepthi commented on COLLECTIONS-424:
---------------------------------------------
I have uploaded the patch. Here is the brief explanation of the changes i made
in the current files.
1. Composite Collection holds the collections added to it in List<E> instead of
List<Collection<E>>.This solves the issue of type checking in the code as
mentioned in the bug.
2. I see add() and addComposited() performing the same functionality according
to the current version.Whereas according to the apache commons collections
doc,the functionalities are supposed to be different as shown below.
add(java.lang.Object obj)
Adds an object to the collection, throwing
UnsupportedOperationException unless a CollectionMutator strategy is specified.
addAll(java.util.Collection coll)
Adds a collection of elements to this collection, throwing
UnsupportedOperationException unless a CollectionMutator strategy is specified.
addComposited(java.util.Collection c)
Add an additional collection to this composite.
But according to the current version,both does the same thing.In that case i
don't see the need of having two methods for the same functionality.So i
changed the functionality of the methods according to the document.
3. I changed the junit test cases accordingly and uploaded in the patch.
> Surprising exception by CompositeSet in a situation where CompositeCollection
> works fine
> ----------------------------------------------------------------------------------------
>
> Key: COLLECTIONS-424
> URL: https://issues.apache.org/jira/browse/COLLECTIONS-424
> Project: Commons Collections
> Issue Type: Bug
> Components: Set
> Affects Versions: 3.2.1
> Environment: All environments
> Reporter: Michael Pradel
> Attachments: collections424.patch
>
>
> We have a method that uses a CompositeCollection. Here's a simplified version
> of it:
> void m(CompositeCollection coll) {
> coll.addComposited(new TreeBag());
> }
> It works fine when the argument is a CompositeCollection, but it throws an
> exception when the argument is a CompositeSet. E.g.:
> m(new CompositeCollection()); // OK
> m(new CompositeSet()); // IllegalArgumentException
> Although the exception is documented in CompositeSet, this behavior is very
> surprising. Is there a way to have m() accept CompositeCollections without
> running into this exception? The only solution that comes to my mind is to
> dynamically check the type of 'coll' in m(), but this is a rather nasty
> work-around.
> A better solution may be to make the genericity of CompositeCollection
> explicit by adding a type parameter:
> class CompositeCollection<T extends Collection> {
> void addComposited(T c) { /* .. */ }
> }
>
> class CompositeSet extends CompositeCollection<Set> {
> @Override void addComposited(Set c) { /* .. */ }
> }
> This way, users of CompositeCollection must choose the kind of collections
> that can be composed and will not encounter surprises, such as the above.
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