Run function on JFrame close

Question

void terminate() {}
protected JFrame frame = new JFrame();

How can I get frame to run the terminate function when I press the close button?

Edit: I tried to run this, but for some reason it doesn't print test (however, the program closes). Does anyone have an idea what could be the problem?

frame.addWindowListener(new WindowAdapter() {
    public void WindowClosing(WindowEvent e) {
        System.out.println("test");
        frame.dispose();
    }
});

Kirbykirch

Answer 1

You can use addWindowListener:

frame.addWindowListener(new WindowAdapter() {
    public void windowClosing(WindowEvent e) {
        // call terminate
    }
});

See void windowClosing(WindowEvent e) and Class WindowAdapter too.

Heid

Will I have to create a new class that extends JFrame and implements WindowAdapter? (or is it ok to keep frame as a JFrame?) It doesn't really work yet, and I get the warning "The method WindowClosed(WindowEvent) from the type new WindowAdapter(){} is never used locally" on the WindowClosing function – Kirbykirch

windowClosing and not WindowClosing with uppercase W. – Heid

Answer 2

Not only do you have to add the window listener, you have to set the default close operation to do nothing on close. This allows your code to execute.

frame.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
frame.addWindowListener(new WindowAdapter() {
    @Override
    public void windowClosing(WindowEvent event) {
        exitProcedure();
    }
});

Finally, you have to call System exit to actually stop your program from running.

public void exitProcedure() {
    frame.dispose();
    System.exit(0);
}

Beacon

+1 for the answer, but especially @Override. Very good advice. No (reconsiders) excellent advice. :) – Leadsman

Remove the frame.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE); – Bailiff

Answer 3

Frame.dispose() method does not terminate the program. To terminate the program you need to call System.exit(0) method

Quatrefoil

Answer 4

If you want to terminate your program after the JFrame is closed, you have to set the default close operation on your JFrame.

In your constructor of your JFrame write:

setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

If you just want to call a method when the window is closed and not terminate the whole program, than go with the answer of Maroun.

Labbe

I would like to do both (run a function, then terminate). Here's my current code: frame.addWindowListener(new WindowAdapter() { public void WindowClosing(WindowEvent e) { System.out.println("test"); frame.dispose(); } }); The problem is that it doesn't print "test". Do you have any idea what could be the problem? – Kirbykirch

The method is "windowClosing" not "WindowClosing". You need to override it, so it has to be the exact name. – Labbe