Detect if Java Swing component has been hidden

Question

Assume we have the following Swing application:

    final JFrame frame = new JFrame();

    final JPanel outer = new JPanel();
    frame.add(outer);

    JCompon         


        

Answer 1

Have a look at the ComponentListener (or ComponentAdapter)

http://java.sun.com/docs/books/tutorial/uiswing/events/componentlistener.html

http://docs.oracle.com/javase/8/docs/api/java/awt/event/ComponentListener.html

And specifically the method:

void componentHidden(ComponentEvent e)
    Invoked when the component has been made invisible.

A complete solution would look something like:

inner.addComponentListener(new ComponentAdapter() {
    public void componentHidden(ComponentEvent ce) {
        System.out.println("Component hidden!");
    }
});

If the actions that should be carried out upon hiding is tightly coupled with the SomeSpecialCompnent, I would suggest to let SomeSpecialComponent implement ComponentListener, and add itself as a listener for the ComponentEvents in its constructor.

Another useful way (more related to add/remove operations and perhaps not suitable for your specific scenario) is to override addNotify() and removeNotify().