Second JFrame closes first

Question

two JFrames,

JFrame Main; // Main JFrame

JFrame Sub; //Second JFrame that is initialized from within Main via a JMenuItems ActionListener.

mainMenuItem.setActionListener(new ActionListener(){
    public void actionPerformed(ActionEvent arg0) {
        try{
            Sub subFrame = new Sub();
            subFrame.setVisible(true);
        }catch(Exception e){}
        }
    });
}

The problem is whenever i close the second JFrame (Sub) it closes the first aswell.

Both JFrames have:

setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

Is that part of the problem?

score 5 · Answer 1 · answered Oct 21 '13 at 16:45

EXIT_ON_CLOSE means to exit the program immediately (System.exit()) when the frame is closed.

You probably want to set this to DISPOSE_ON_CLOSE, then add a WindowListener and close the program only if both frames have been closed.

(Or, perhaps you want only the main frame to have EXIT_ON_CLOSE)

score 3 · Accepted Answer · answered Oct 21 '13 at 16:46

3

Yes. JFrame.EXIT_ON_CLOSE by definition exits the application. For your second Frame use DISPOSE_ON_CLOSE or HIDE_ON_CLOSE.

Hope this helps!

answered Oct 21 '13 at 16:46

Mechkov

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score 2 · Answer 3 · edited May 23 '17 at 11:57

You state:

JFrame Sub; //Second JFrame that is initialized from within Main via a JMenuItems ActionListener.

This suggests you've a design problem:

Your 2nd "frame" shouldn't even be a JFrame since it is not behaving as a separate independent main program window.
Instead it's acting as a dialog since it is dependent on and shown from a parent window, the main JFrame. So make the secondary window a JDialog not a JFrame, and all these problems will go away.
You will need to consider whether it should be a modal dialog where the main window is not accessable to the user while the dialog is open, or a non-modal dialog.
Having said that, you may even be better off using one window/JFrame and swapping views via a CardLayout.

Please read this link: The Use of Multiple JFrames, Good/Bad Practice?, and in particular please have a look at Andrew Thompson's community wiki answer.

Thanks, i didnt realise it was bad practice to have multiple JFrames. I just want a pop up window with some text like the "about" window that most software contains where you see the version number etc. What would be a better way of doing this without another JFrame? — Eduardo, Oct 21 '13 at 17:31
@clairharrison: again what you are trying to do is show a dialog window. The standard way to do this is as I describe above in my answer. — Hovercraft Full Of Eels, Oct 21 '13 at 18:13

Second JFrame closes first

3 Answers3