How can a Swing WindowListener veto JFrame closing

Question

I have a frame, and want to prompt when the user closes it to save the document. But if they cancel, the frame shouldn\'t close.

frame.addWindowListener(new          


        

Answer 1

I think that this is the logical expression of Thirler's answer, and kind of what I was trying to avoid.

frame.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
frame.addWindowListener(new SaveOnCloseWindowListener(fileState, JFrame.EXIT_ON_CLOSE));

public class SaveOnCloseWindowListener extends WindowAdapter {

    private final int closeOperation;
    private final Document document;

    public SaveOnCloseWindowListener(int closeOperation, Document document) {
        this.closeOperation = closeOperation;
        this.document = document;
    }

    public void windowClosing(WindowEvent e) {
        if (!document.onClose())
            doClose((Window) e.getSource());
    }

    private void doClose(Window w) {
        switch (closeOperation) {
        case JFrame.HIDE_ON_CLOSE:
            w.setVisible(false);
            break;
        case JFrame.DISPOSE_ON_CLOSE:
            w.dispose();
            break;
        case JFrame.DO_NOTHING_ON_CLOSE:
        default:
            break;
        case JFrame.EXIT_ON_CLOSE:
            System.exit(0);
            break;
        }
    }
}