Get Random Element from Collection

Question

I have a Collection<Obj> how do I get a random Obj from it?

I've checked the docs and there doesn't seem to be a way, since iterator is the only way to access the collection. Do I have to iterate over it to get a random object!?

Answer 1

Using Lambdas you can do this quite quickly and handle the case when Collection is empty.

public static <E> Optional<E> getRandom (Collection<E> e) {

    return e.stream()
            .skip((int) (e.size() * Math.random()))
            .findFirst();
}