两个系列之间的区别？ （collection1中的元素，但不在collection2中）

Question

In Java (maybe using Guava?), is there some method provided to get the difference of two Collection s, eg a List and a Set without modifying one of these Collection s (else there would be collection1.removeAll(collection2) ?

In Guava there is Sets.difference(set1,set2) , but it only works for Set s, not for arbitrary collections.

Thanks for any hint!

Answer 1

You can filter the first Collection using built-in Predicate s:

Collections2.filter(c1, Predicates.not(Predicates.in(c2))

It works with any kind of Collection s, but obviously it's better if c2 is a Set .

Answer 2

ApacheCommons CollectionUtils has a method named disjuction that

Returns a Collection containing the exclusive disjunction (symmetric difference) of the given Iterables