Re: Adding ExitListeners to Netbeans generated Desktop Application?

"Rexx Magnus" <>
Thu, 07 Aug 2008 17:18:07 +0100
On Thu, 07 Aug 2008 16:08:18 +0100, John B. Matthews =

<nospam@nospam.invalid> wrote:

Ah, I see. The problem isn't NetBeans itself; it's (protected) GUI cod=


generated by NetBeans. You only need to invoke setQuitHandler(), but y=


need to do it in the JFrame's constructor.

FWIW, the ant target "package," which builds a Mac application bundle,=

is somewhat more transparent than the corresponding Xcode facility.

I look forward to hearing how this progresses.

It's proven to be simpler than expected (for handling Mac menu events, =

that is). Instructions on how I got the hooks to work easily are below. =

Right at the bottom is the problem I still haven't yet fixed (regards to=

catching the close action).

In the variables section of your application's GUI class (usually =

something-View in the case of netbeans):

     public static boolean MAC_OS_X = =

(System.getProperty("").toLowerCase().startsWith("mac os x"));
     final static int MENU_MASK = =


They detect which OS you're running, and the format of the shortcut keys=

(not sure how necessary the latter is).

After the netbeans generated Code at the beginning of your GUI =

public MyAppView(SingleFrameApplication app) {

I simply place:
    if (MAC_OS_X){
        //hide the menus if it's running on a Mac.

This enables you to check at runtime whether you're running on a Mac and=

then destroy the menu so it fits the usual look and feel of Mac OS X. It=
's =

a bit of a kludge, but it seemed to be the only way of removing the menu=
s =

since the construction code is guarded (not that I'm complaining).

In the IDE generated code for the GUI (after the constructor, not within=

it obviously), you can simply insert the registerForMacOSXEvents() metho=
d =

and then include the class in your project, replacing th=
e =

default package name with the one for your project.
That then provides for the About, Preferences, File (open) and Quit menu=
s =

which are the usual items for Mac apps.

My version of the method is trimmed down, as I only need a Quit/Exit and=

About menu:
      public void registerForMacOSXEvents() {
         if (MAC_OS_X) {
             try {
                 // Generate and register the OSXAdapter, passing it a h=
ash =

of all the methods we wish to
                 // use as delegates for various = methods
                 OSXAdapter.setQuitHandler(this, =

getClass().getDeclaredMethod("exitProperly", (Class[])null));
                 OSXAdapter.setAboutHandler(this, =

getClass().getDeclaredMethod("about", (Class[])null));
             } catch (Exception e) {
                 System.err.println("Error while loading the OSXAdapter:=
The OSXAdapter.setXXXXHandler methods simply get given the actual name o=
f =

the method you wish to call from your GUI's class. In my example, I'm =

calling exitProperly() - note that there are no brackets in the string =

passed as the method names above.

The problem I'm having now is that when I have attached a WindowListener=

which then points to my exitProperly() method, it carries out those =

actions, but is still closing the window if I add a "Do you wish to quit=
?" =

dialog. It seems that the default close action is not being set to do =

I had the following code just after the initComponents() line:
    this.getFrame().addWindowListener(new Closer());

    //I've also tried this, but this gives an error saying it can't be =

    //app being mentioned at the start of the constructor and as super(app)=
    app.addExitListener(new Closer());

Now this works fine for the non-resizing window and also adds the =

listener, which gets executed when you close the window. However it is =

still exiting the program after performing my specified task in the =

exitProperly() method. The only reason I can see for this is that I am n=
ot =

setting the default close operation for the right 'thing'. If I could wo=
rk =

out what to apply the default close operation to, I won't need to add an=

exitlistener (which I don't think would help, as I need to be able to =

totally abort the close operation).
The official Mac example is of no use as it basically closes the window,=

but not the menu when you shut it (via the window close button) - then i=
f =

you quit via the menu which is the normal mac method for multiwindow app=
s, =

it pops back up but then closes. They don't seem to have catered for =

single-window applications in that regard, but that's because it basical=
ly =

uses the method I have below - it seems that if it returns true, it quit=
s, =

if it doesn't then it doesn't quit, or at least it shouldn't - if you =

override the default close operation.

I am truly poking around in the dark on this one, as I don't understand =

the way that Netbeans has formed the application.

     public boolean exitProperly() {
         boolean val = false;
         if ((JOptionPane.showConfirmDialog(null, "Are you sure?", "Quit=
", =

JOptionPane.YES_NO_OPTION)) == JOptionPane.YES_OPTION) {
             val = true;
             System.out.println("yes came up, I saved");
         } else {
             System.out.println("no came up");

         return val;

     public class Closer extends WindowAdapter {

         public void windowClosing(WindowEvent e) {

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