How does an ActionListener work?

java swing actionlistener
aditya_gaur picture aditya_gaur · Feb 3, 2011 · Viewed 10.4k times · Source

I have an idea of how to use action listeners and implementing them but I was wondering if anyone could tell me how do they listen to the events? Is there some kind of polling mechanism?

Answer

Joel picture Joel · Feb 3, 2011

Action listeners register for Events using the Observer pattern and they are notified, by the main event loop, of any events they are registered for. So no, it's not a polling (pull) mechanism, but the opposite - a (push) callback. This is an example of 'don't call us, we'll call you' programming. Because everything in your code runs off a single thread (the event loop) you don't have to worry about synchronizing between different events - so your code is threadsafe.

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