A Listener solution based on Generics and Dynamic Proxies

Question

Listeners are common in the java world, espacially in swing. It is easy to implement a listener, and it is easy to call an existing method that notifies all registered listeners, but it's laborious to implement this notification code itself.
I present a small, typesafe solution called GenericListeners based on Dynamic Proxies and Generics that reduces the notification code to just a single line of code:
IGenericListeners<FooListener> fooListeners = GenericListeners.create(FooListener.class);If FooListener looks like
public interface FooListener {
  public onEnter(int id);
  public onExit();
}then you can register and call Listeners with
fooListeners.addListener(foo);
fooListeners.call().onEnter(1);If you are interested, please have a look at
http://www.sebastian-baltes.de/SebWiki/Wiki.jsp?page=GenericListeners
What do you think about this?
Message was edited by:
Sebastian_Baltes

Answer 1

Interesting point, and so I've done some tests:
0:00:01.391 - plainest implementation
0:00:02.469 - GenericListeners
0:00:03.422 - javax.swing.event.EventListenerListI used a test that registers a listener and calls it 10,000,000 times in a for loop on Java 6, AMD Athlon 3000.
I would say that GenericListeners performs well, especially compared to the EventListenerList that is used in all swing components. The problem with EventListenerList is that it stores different classes of listeners at once and has to find the right ones every time you raise an event. For my tests, I only stored one single listener into the list.
You can imagine how bad the performance of the swing implementation would be if you have a real life example with a lot of different listener classes.