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When to use anonymous class

Krishnamurthy Dara

Joined: Jul 27, 2006
Posts: 7
Hi All,

I am developing a screen in applets which contains 5 Buttons. I need to handle all buttons action events. For this I have two choices to do.

1.Adding action listeners to all buttons and handling the events in single method called
public void actionPerformed(ActionEvent actionEvent) {} with five if else condition checking.

2.I can write actionPerfomed method for each and every button by using ActionListener() Anonymous Class.
eg: sendButton.addActionListener(new ActionListener(){

public void actionPerformed(ActionEvent e) {

Please suggest me which one is better in terms of different prospects like performance and coding standards......
Campbell Ritchie

Joined: Oct 13, 2005
Posts: 36478
Performance: don't know.

If you search these fora, you will find differing opinions, some people favouring anonymous classes, others disliking them. Fortunately there are few people who recommend "addActionListener(this);"

I am one of those hwo like anonymous inner classes, but have a little rule of thumb:-
If your Listener does something completely different from all the other Listeners, then anonymous is easiest to code. Keep the code in the actionPerformed() method short; it might be better to call a method elsewhere in the class than to have a long actionPerformed() method.

If you have two Listeners which do the same thing, or several similar things, then you are better off with a named Listener class.

But I think the actionPerformed method with banks of if elses in is an abomination against good programming.

I have posted replies to similar questions many times, Here I was quite restrained.
Paul Clapham

Joined: Oct 14, 2005
Posts: 18118

Originally posted by Campbell Ritchie:
Performance: don't know.
I would go farther than that: you would have to do some seriously awful programming to make any noticeable difference, performance-wise, no matter what choice you made.

As for coding standards, if the coding standards at your place of work require (or forbid) inner classes then follow the coding standards.

And for the general advice, I agree completely with Campbell Ritchie.
Krishnamurthy Dara

Joined: Jul 27, 2006
Posts: 7
Thank you very much Campbell and Paul for your reply. Hope there is no much difference in Perfomance also..
Campbell Ritchie

Joined: Oct 13, 2005
Posts: 36478
. . . only too pleased to be able to help.
Ilja Preuss

Joined: Jul 11, 2001
Posts: 14112
Originally posted by Krishnamurthy Dara:
Hope there is no much difference in Perfomance also..

The difference should be at an order of magnitude of nano- to micro-seconds.

The soul is dyed the color of its thoughts. Think only on those things that are in line with your principles and can bear the light of day. The content of your character is your choice. Day by day, what you do is who you become. Your integrity is your destiny - it is the light that guides your way. - Heraclitus
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subject: When to use anonymous class
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