Java Coding Problems

Custom collecting via collect()

In the case of an IDENTITY_FINISH collection operation, there is at least one more solution for obtaining a custom collector. This solution is facilitated by the following method:

<R> R collect​(Supplier<R> supplier, BiConsumer<R,​? super T> accumulator, BiConsumer<R,​R> combiner)

This flavor of collect() is a great fit as long as we deal with an IDENTITY_FINISH collection operation and we can provide a supplier, accumulator, and combiner.

Let's take a look at some examples:

List<String> numbersList = Stream.of("One", "Two", "Three")  .collect(ArrayList::new, ArrayList::add,    ArrayList::addAll);Deque<String> numbersDeque = Stream.of("One", "Two", "Three")  .collect(ArrayDeque::new, ArrayDeque::add, ArrayDeque::addAll); ...