java - Prevent/Cancel closing of primary stage in JavaFX 2.2

Question

As the title says, my question is, how can I prevent/cancel closing of primary stage in JavaFX 2.2? I have done some research on Google, and the following two links seemed to address the issue:

• Prevent or cancel exit JavaFX 2
• Thread: JavaFX 2.0 Stage onClose event

I tried the methods explained by those two links, but sadly for me, none of them works. So, without further ado, here is what I had done.

Firstly, I tried to attach an OnCloseRequest to the primaryStage as follows.

primaryStage.setOnCloseRequest(new EventHandler<WindowEvent>() {
    @Override
    public void handle(WindowEvent event) {
        if (!canExit()) {
            event.consume();
            primaryStage.show(); // I tried without this line also.
        }
    }
});

When canExit() returns false, I tried to prevent the event from propagating further and cause to exit the app by callingevent.consume(). But the stage is getting closed/hidden and I got the following error messages on Netbeans output window. It keeps coming repeatedly until I force close the app from Netbeans.

(java:6731): Gtk-CRITICAL **: IA__gtk_widget_get_visible: assertion `GTK_IS_WIDGET (widget)' failed

(java:6731): Gtk-CRITICAL **: IA__gtk_widget_get_visible: assertion `GTK_IS_WIDGET (widget)' failed

(java:6731): Gtk-CRITICAL **: IA__gtk_widget_get_visible: assertion `GTK_IS_WIDGET (widget)' failed

Having tasted failure in this attempt, I changed OnCloseRequest to OnHiding with the expectation of success.

primaryStage.setOnHiding(new EventHandler<WindowEvent>() {
    @Override
    public void handle(WindowEvent event) {
        if (!canExit()) {
            event.consume();
            primaryStage.show(); // I tried without this line also.
        }
    }
});

Although, I tasted failure in this attempt too, I think I have made some progress. There is no error messages this time, and no need to force close the application from Netbeans.

Then I read about some magic method named setImplicitExit() in the Platform class. Thinking that this is what I was missing, I tried Platform.setImplicitExit(false); with both of the two methods as follows:

1. OnCloseRequest version

   Platform.setImplicitExit(false);
   
   primaryStage.setOnCloseRequest(new EventHandler<WindowEvent>() {
       if (!canExit()) {
           // ...
       } else {
           Platform.exit();
       }
   });
   

   No difference, the stage gets closed/hidden, and the same error message comes repeatedly.

2. OnHiding version

   Platform.setImplicitExit(false);
   
   primaryStage.setOnHiding(new EventHandler<WindowEvent>() {
       if (!canExit()) {
           // ...
       } else {
           Platform.exit();
       }
   });
   

   Beginning on a positive note, the application doesn't get exited as earlier. But, the negative note is that the stage is still getting closed/hidden.

Now, I am out of weapons/equipments in my armoury to solve it, and so I am here to request the help of you heroes and champions. So, How can I solve this problem or what have I done wrong or what am I missing?

Answer 1

I have used following code in my application and it works perfectly,

Platform.setImplicitExit(false);

primaryStage.setOnCloseRequest(new EventHandler<WindowEvent>() {
    @Override
    public void handle(WindowEvent event) {
        event.consume();
    }
});