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https://issues.apache.org/jira/browse/COLLECTIONS-528?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13999902#comment-13999902
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Thomas Neidhart commented on COLLECTIONS-528:
---------------------------------------------
I think it makes sense.
What do you think about using an Equator rather than a Comparator?
The call would be then like this:
{noformat}
final Collection<myClass> result = CollectionUtils.removeAll(base, sub, new
DefaultEquator<myClass>() {
public boolean equate(myClass o1, myClass o2) {
return o1.getB() == o2.getB();
}
});
{noformat}
> Add removeAll(Collection<E> collection, Collection<E> remove, Comparator<E>
> comparator) and contains(Collection<E> collection, E object, Comparator<E>
> comparator) methods
> --------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
> Key: COLLECTIONS-528
> URL: https://issues.apache.org/jira/browse/COLLECTIONS-528
> Project: Commons Collections
> Issue Type: Improvement
> Components: Collection
> Reporter: Alexander Muthmann
>
> Hi,
> this request originates from one of our project where we have implemented
> something similar.
> The Java-Interface java.util.Collection<E> specifies the two methods
> contains(Object o) and boolean removeAll(Collection<?> c). Both methods rely
> on the equals() method of the given Objects.
> In some cases, it's not possible to change those methods and therefore
> removeAll and contains cannot be used directly.
> E.g. if you have an class myClass with property A and B and the equals method
> uses both properties, but you are only interested in property B.
> To solve this problem, I'd like to propose the following extensions of
> CollectionsUtils:
> {code}
> /**
> * Removes all elements of remove from the collection using the comparator
> instead of .equals()
> */
> public static <E> Collection<E> removeAll(final Collection<E> collection,
> final Collection<E> remove, Comparator<E> comparator);
> /**
> * Checks if the given collection contains the object using the comparator
> instead of .equals()
> */
> public static <E> boolean contains(final Collection<E> collection, final E
> object, Comparator<E> comparator);
> {code}
> Both methods do basically the same as their native equivalient but use a
> comparator instead of equals().
> This allows the injection of any required compare value:
> {code}
> final Collection<myClass> result = CollectionUtils.removeAll(base, sub, new
> Comparator<myClass>() {
> public int compare(myClass o1, myClass o2) {
> return o1.getB() == o2.getB();
> }
> });
> {code}
> If you think those methods are a good idea (as proposed or changed according
> to any rules), please give me a short feedback and I'll offer an
> implementation as diff patch for review.
> Cheers,
> Alex
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