Swing Hacks

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Chapter 12, Miscellany

#94 Fire Events and Stay Bug Free

HACK

H A C K

#94

Fire Events and Stay Bug Free Hack #94

Most developers think that writing an event-firing method is trivial. Most

developers are wrong.

As you develop your own Swing components, it’s likely that you’ll eventu-

ally need to have them fire off events; this comes up as soon as you have a

model that needs to update a view. If you’ve strongly typed everything by

writing new classes for the model, view, event, and listener, then you’ll have

to write your own fire method.

Most developers assume this to be trivial. For example, to manage a list of

FooListeners, they’ll typically maintain a Vector or ArrayList and fire off the

event with a block like this:

Iterator it = listeners.iterator( );

while (it.hasNext( ))

((FooListener).it.next( )).handleEvent (fooEvent);

And there you have it. It’s simple. It’s clean. It’s elegant. It’s wrong.

Figure 12-9. Incremental self-loading with a progress bar