Event Loop Implementation

EventLoop.java

/*
    Java implementation of Event Loop
    
    Event Loop contain:
        - List of event
        - List of handler corresponding to each event data
*/

public final class EventLoop {

    public static final class Event {
        private final String key;
        private final Object data;
        public Event(String key, Object data) {
            this.key = key;
            this.data = data;
        }
    }

    private final ConcurrentLinkedDeque <Event> events = new ConcurrentLinkedDeque <> ();
    private final ConcurrentHashMap <String, Consumer <Object>> handlers = new➥ ConcurrentHashMap <> ();

    public EventLoop on(String key, Consumer <Object> handler) {
        handlers.put(key, handler);
        return this;
    }

    public void dispatch(Event event) {
        events.add(event);
    }

    public void stop() {
        Thread.currentThread().interrupt();
    }

    public void run() {
        while (!(events.isEmpty() && Thread.interrupted())) {
            if (!events.isEmpty()) {
                Event event = events.pop();
                if (handlers.containsKey(event.key)) {
                    handlers.get(event.key).accept(event.data);
                } else {
                    System.err.println("No handler for key " + event.key);
                }
            }
        }
    }
}

public static void main(String[] args) {
    EventLoop eventLoop = new EventLoop();
    new Thread(() -> {
        for (int n = 0; n <6; n++) {
            delay(1000);
            eventLoop.dispatch(new EventLoop.Event("tick", n));
        }
        eventLoop.dispatch(new EventLoop.Event("stop", null));
    }).start();

    new Thread(() -> {
        delay(2500);
        eventLoop.dispatch(new EventLoop.Event("hello", "beautiful world"));
        delay(800);
        eventLoop.dispatch(new EventLoop.Event("hello", "beautiful universe"));
    }).start();

    eventLoop.dispatch(new EventLoop.Event("hello", "world!"));
    eventLoop.dispatch(new EventLoop.Event("foo", "bar"));

    eventLoop.on("hello", s -> System.out.println("hello " + s))
        .on("tick", n -> System.out.println("tick #" + n))
        .on("stop", v -> eventLoop.stop())
        .run();

    System.out.println("Bye!");

}

private static void delay(long millis) {
    try {
        Thread.sleep(millis);
    } catch (InterruptedException e) {
        throw new RuntimeException(e);
    }
}

/*
    hello world!
    No handler for key foo
    tick #0
    tick #1
    hello beautiful world
    tick #2
    hello beautiful universe
    tick #3
    tick #4
    tick #5
    Bye!
 */