How could I get the number of visible windows of my app?

Question

Or more exact:

I need to know on a window close event, if any other window is still visible.

If not, System.exit(0) would be called.

Answer 1

1) I need to know on a window close event

there are WindowConstants and WindowEvent

2) if any other window is still visible.

you can get number of Top-Level Containers by using Window[] wins = Window.getWindows(); for testing their visibility or by adding WindowStateListener

some important notice here

Answer 2

Try

if(Frame.getFrames().length == 0) {
    // work here.
}

(Frame is java.awt.Frame, that is the parent of JFrame, so you will capture them, too).

Answer 3

Thanks to everyone for answers. With this help I managed to get a working solution:

Strange, it doesn't works with windowClosed. Only works with windowClosing.

Code

public final class CloseOnLastWindowListener extends WindowAdapter {

    @Override
    public void windowClosing(WindowEvent e) {
        System.out.println("\tCLOSING!!!");

        int nRelevant = 0;
        for (Window w : Window.getWindows()) {
            // get only visible windows, except the one being closed
            if (w != e.getWindow() && w.isVisible()) {
                System.out.println("\tRELEVANT: " + w);
                ++nRelevant;
            } else {
                System.out.println("\tirrelevant: " + w);
            }
        }

        if (nRelevant == 0) {
            System.out.println("\tEXIT!!!");
            System.exit(0);
        }
    }
}

Answer 4

I need to know on a window close event, if any other window is still visible. If not, System.exit(0) would be called.

Just use:

frame.dispose();

When the last window is close the JVM will exit automatically.

Or when you create you frames and dialogs use:

frame.setDefaultCloseOperation(JFrema.DISPOSE_ON_CLOSE);