Preventing a PApplet closing the calling Java program

edited April 2016 in How To...

Ok, so I have this Java Program developed primarily in Swing (Enthusiasm yay!). A small part of it uses Unfolding, a processing library for create maps (like geographical maps). Anyway, all of this is built in a class called MapProcessingApplet an extension of PApplet.

Now to open this window from the calling window I implement and actionlistener on a button, await the click and then do the following:

MapProcessingApplet mapApplet = new MapProcessingApplet();
PApplet.runSketch(new String[]{"<Package>.MapProcessingApplet"}, mapApplet);

(Where the is actually configured correctly).

Now, this runs fine, the window opens, it shows a rather lovely map (thank you, unfolding), but when I click the close button (the cross in the top right) it doesn't just close the PApplet window, it also closes the window from which I call it and terminates the entire program.

Is there a way to prevent it from doing this?

(You know, because kamikaze maps are cool and all, but not really what the end user is looking for in a program)


  • Thank you, except I think I'm using processing 2 not processing 3, I am assuming I remove window listeners from the frame rather than the surface right?

  • Yes remove them from the frame.

  • edited March 2016

    Variable frame in both P2 & P1 is already a JFrame.
    I guess it's very easy to adapt my solution to old Processing versions. :D

  • the frame variable is actual just a Frame although it can be cast to a JFrame. I cast it to JFrame and did:

    ((JFrame) frame).setDefaultCloseOperation(HIDE_ON_CLOSE);

    with no success, also removed the WindowListeners

  • edited March 2016

    The frame variable is actual just a Frame although it can be cast to a JFrame.

    Indeed field frame is declared as datatype Frame. However it points to a JFrame object instead. :P

    ... with no success, ...

    My solution relies on class Window's removeWindowListener() method: :-B

    static final void removeExitEvent(final PSurface surf) {
      final java.awt.Window win
        = ((processing.awt.PSurfaceAWT.SmoothCanvas) surf.getNative()).getFrame();
      for (final java.awt.event.WindowListener evt : win.getWindowListeners())
  • Ok, but PSurface doesn't seem to be part of the Processing 2 Core library

  • Did you remove all WindowListeners?

    If you have removed them all you can try the DO_NOTHING_ON_CLOSE option and add your own WindowListener/ WindowAdapter to handle the window closing event.

  • Actually that's probably a more elegant solution, I'll try attaching my own WindowListener event. The DO_NOTHING_ON_CLOSE seems to be having no effect.

  • Ok, so removing all the WindowListeners and attaching my own to open a new window hasn't worked either. It kills even the newly open window

  • It is the approach I took in the G4P library and it worked for me. :)

  • edited March 2016

    Ok, but PSurface doesn't seem to be part of the Processing 2 Core library...
    Thank you, except I think I'm using Processing 2 not Processing 3, ...

    • You've already confirmed you're using P2.
    • I have already told you that you need to port my P3 solution to P2.
    • And I have already told you that frame already points to a JFrame object.
  • Ok, well I've attempted to port you solution. I created a loop for removing all the WindowListeners from the JFrame. I ran this program in a Debugging session and did a variable watch on the JFrame in PApplet.

    Upon inspection of the WindowListeners within this frame, there were no windowListeners set to the PApplet.

    As far as I can tell all windowListeners have been removed from the frame. The default close operation was also set on both "HIDE ON CLOSE" and "DO NOTHING ON CLOSE"

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