🚀 go-pugleaf

Thanks for your comments John, now I know a bit more about Java's internal
life.

Now I am having problems with the following feature. I want to cancel
termination of application in "windowclosing" event, but it does not work as
expected.

If I select "yes" from the confirmdialog, then application is terminated
(windowclosing and windowclosed handlers are called).
If I select "no" from the confirmdialog, then application keeps running BUT
still main window dissapear from the screen. Main window is a subclass of
JFrame.

How to cancel terminaton and still keep main window visible on screen?

====
[Snippet from code]

  void mnuitmExit_actionPerformed(ActionEvent e) {
    // this will invoke "windowclosing" handler
    this.dispatchEvent(new WindowEvent(this, WindowEvent.WINDOW_CLOSING));
  }

  void this_windowClosing(WindowEvent e) {
    if (JOptionPane.showConfirmDialog(this,
          "Do you want to close application?",
          "Exit",
          JOptionPane.YES_NO_OPTION, JOptionPane.QUESTION_MESSAGE) ==
JOptionPane.YES_OPTION) {
      System.out.println("Exit...");
      this.dispose();   // release native window resources and invokes
"windowclosed" handler
    } else {
      // cancel exit and continue running application
      this.setVisible(true);
      System.out.println("Cancel...");
    }
  }
  void this_windowClosed(WindowEvent e) {
    System.out.println("Exit done.");
    System.exit(0);
 }


====
John P. McGrath kirjoitti viestiss� ...
>On Wed, 19 Jul 2000 12:50:49 +0300, X_Aki Nieminen_X wrote:
>
>> If I call "this.dispose()" inside button handler, then
>> "windowClosing" event handler is never called, but only
>> "windowClosed" one.
>>
>> Finally, I created explicitly a new WindowEvent and
>> dispatch it to dialog instance. See my code below with
>> dispatching code.
>>
>> Is it legal to do it this way in Java to handle window
>> close operation, can I dispatch window message without
>> any side effects?  Is there some better and efficient
>> way to this?
>
>I think you got it right.
>
>The windowClosing() event is poorly named, which is the source of much
>confusion.  It is sent by the operating system to request that the window
>be closed.  This occurs on Windows when you press the close [x] button,
>choose "Close" from the system menu, or press Alt+F4.  Other operating
>systems have their own ways to send the event.
>
>The windowClosing() event does not actually close the window -- it is
>your dispose() call that closes it.  If you want, you can ignore the
>event, and then the close button will do nothing.
>
>Since you call dispose(), the window is closed.  The operating system
>then notifies your program that the window has been closed, and Java lets
>your code know by sending the windowClosed() event.
>
>If the AWT designers had thought about it a little more, they would have
>used a name like windowCloseRequest() rather than windowClosing().  This
>would have avoided a lot of confusion.
>
>--
>Regards,
>
>John McGrath