How to minimize a jFrame when the window close button is pressed?

Question

I want to minimize the JFrame when the close button is pressed, I am using the code shown below, but whenever I press the close button, the frame first minimizes and then closes automatically. I am working on Ubuntu.

How can I prevent the JFrame from closing?

public class MainClass {

    public static void main(String args[]) throws ClassNotFoundException {

        final Gui frame = new Gui();

        frame.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                frame.setExtendedState(Frame.ICONIFIED);
            }
        });

    }
}

Answer 1

Try maybe this way

final Gui frame = new Gui();
frame.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);// <- prevent closing
frame.addWindowListener(new WindowAdapter() {
    public void windowClosing(WindowEvent e) {
        frame.setExtendedState(JFrame.ICONIFIED);
    }
});

frame.setSize(200,200);
frame.setVisible(true);

This will prevent window from closing, and your current code will minimize it (at least this is how it works on Win7, let me know if it helps or not).