Collections: BlockingQueue coordinates producer and consumer

var queue = new ArrayBlockingQueue<Integer>(2);
var results = Collections.synchronizedList(new ArrayList<Integer>());

Thread producer = new Thread(() -> {
    try {
        for (int i = 1; i <= 5; i++) queue.put(i);
        queue.put(-1);                       // poison pill
    } catch (InterruptedException e) { Thread.currentThread().interrupt(); }
});
Thread consumer = new Thread(() -> {
    try {
        int v;
        while ((v = queue.take()) != -1) results.add(v);
    } catch (InterruptedException e) { Thread.currentThread().interrupt(); }
});

producer.start(); consumer.start();
producer.join(); consumer.join();
System.out.println("consumed in order: " + results);

consumed in order: [1, 2, 3, 4, 5]