Alexander Muthmann created COLLECTIONS-528:
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Summary: 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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