Java parallel stream: how to wait for threads for a parallel stream to finish?

Question

So I have a list from which I obtain a parallel stream to fill out a map, as follows:

Map map = new HashMap<>();
List

        

Answer 1

I would guess that if it is possible for the stream to still be processing you could try something like:

    List list = new ArrayList<>();

    //Putting data from the list into the map
    Map map = list.parallelStream()
            .collect(Collectors.toMap(
                    n -> n.getId(),
                    n -> new TreeNode(n)
            ));

At least now you have a terminal on the stream. You will use multiple threads possible and the mapping is certainly going to be complete.