I have a collection of objects that I would like to partition into two collections, one of which passes a predicate and one of which fails a predicate. I was hoping there would be a Guava method to do this, but the closest they come is filter, which doesn't give me the other collection.
I would image the signature of the method would be something like this:
public static <E> Pair<Collection<E>, Collection<E>> partition(Collection<E> source, Predicate<? super E> predicate)
I realize this is super fast to code myself, but I'm looking for an existing library method that does what I want.
Use Guava's Multimaps.index
.
Here is an example, which partitions a list of words into two parts: those which have length > 3 and those that don't.
List<String> words = Arrays.asList("foo", "bar", "hello", "world");
ImmutableListMultimap<Boolean, String> partitionedMap = Multimaps.index(words, new Function<String, Boolean>(){
@Override
public Boolean apply(String input) {
return input.length() > 3;
}
});
System.out.println(partitionedMap);
prints:
false=[foo, bar], true=[hello, world]