Get last element of Stream/List in a one-liner

Question

How can I get the last element of a stream or list in the following code?

Where data.careas is a List:

CArea f         


        

Answer 1

If you need to get the last N number of elements. Closure can be used. The below code maintains an external queue of fixed size until, the stream reaches the end.

    final Queue queue = new LinkedList<>();
    final int N=5;
    list.stream().peek((z) -> {
        queue.offer(z);
        if (queue.size() > N)
            queue.poll();
    }).count();

Another option could be to use reduce operation using identity as a Queue.

    final int lastN=3;
    Queue reduce1 = list.stream()
    .reduce( 
        (Queue)new LinkedList(), 
        (m, n) -> {
            m.offer(n);
            if (m.size() > lastN)
               m.poll();
            return m;
    }, (m, n) -> m);

    System.out.println("reduce1 = " + reduce1);