Preferred style of event handling?

Question

Having developed several java applications I found that my preferred method of event handling in java is to have one component (often named EventHandler) which implements ActionListener's, MouseListener's, ListSelectionListeners, etc. I like this approach because it allows me to finalize code such as menu bars, toolbars, etc and essentially turns the EventHandler into the engine of the application.
The problem I often run into is that while a lot of our code is finalized and can be left alone, the EventHandler becomes monstrously large with all of the logic code necessary to make the application accomplish it's task.
I would really appreciate some ideas/opinions on this topic and possibly ways to improve this design which might make it easier to handle the events of a java app.

Answer 1

I find it useful to create event handlers that focus on a particular function like a toolbar or menubar or whatever. For example, I would create a MyFrameMenuEventHandler for all menu events. If that became to cumbersome I would break the event handler up into menus like MyFrameFileMenuEventHandler and MyFrameEditMenuEventHandler.
All of my event handlers really do nothing but call handler methods on the parent object from which the event originated (usually a frame object). This allows mapping of the same event from different sources to the same handler code.
It also allows subclasses to override the handler methods without needing to modify the event handlers. It is also useful for providing hooks like afterFileOpen and beforeFileOpen for the handleFileOpen handler method.
If the class containing the handler methods becomes to cumbersome you could subclass the frame, for instance, and include a logical subset of handler methods. Provide additional subclasses for the remaining handler methods. For example, you might have MyFrame, which creates components, sets layout, providers component accessor methods, and creates event handlers and registers components. Then create a subclass of MyFrame called MyFrameMenuHandler that contains all handler methods for menu events and so on.
Although if classes start getting this big you probably would need to break it up into logical components to make it more manageable.
I have used this technique both in Java and Forte 4GL--where I original used the technique.