Extending a JFrame

Question

What are the pros and cons of extending a JFrame rather than create a new JFrame?

For example:

public class Test extends JFrame {

setVisible(true);

}

or

public class Test {

JFrame test = new JFrame():

test.setVisible(true);

}

Answer 1

You should not extend a class, unless you want to actually extend its functionality, in the example you've shown, you should use option 2, as option 1 is an abuse of the extending feature.

In other words - as long as the answer to the question is Test a JFrame? is NO, it should not extend JFrame.

Answer 2

pros of not extending JFrame (or any Swing component for that matter):

• Avoid unintentional method overrides. I've stepped into this several times, first when I gave my class int getX() and int getY() methods. Try it and you'll see some not so funny abnormal behaviors.
• Simplify the method options available when using Eclipse or NetBeans to only those methods you've created. This is actually my favorite advantage.
• Gearing your GUI's to create JPanels rather than JFrames which increases deployment flexibility 100-fold.
• And most importantly, exposing only that which needs exposing.