How do I remove an old JPanel and add a new one?

I would like to remove an old JPanel from the Window (JFrame) and add a new one. How should I do it?

I tried the following:

public static void showGUI() {
    JFrame frame = new JFrame("Colored Trails");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);       
    frame.add(partnerSelectionPanel);
    frame.setSize(600,400);
    frame.setVisible(true);
}

private static void updateGUI(final int i, final JLabel label, final JPanel partnerSelectionPanel) {
    SwingUtilities.invokeLater( 
        new Runnable() {
            public void run() {
                label.setText(i + " seconds left.");
            }
            partnerSelectionPanel.setVisible(false); \\ <------------
        }
    );
}

My code updates the "old" JPanel and then it makes the whole JPanel invisible, but it does not work. The compiler complains about the line indicated with <------------. It writes: <identifier> expected, illegal start of type.

ADDED:

I have managed to do what I needed and I did it in the following way:

public static void showGUI() {
    frame = new JFrame("Colored Trails");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);       
    frame.add(partnerSelection开发者_开发百科Panel);
    //frame.add(selectionFinishedPanel);
    frame.setSize(600,400);
    frame.setVisible(true);
}

public static Thread counter = new Thread() {
    public void run() {
        for (int i=4; i>0; i=i-1) {
            updateGUI(i,label);
            try {Thread.sleep(1000);} catch(InterruptedException e) {};
        }
        partnerSelectionPanel.setVisible(false);
        frame.add(selectionFinishedPanel);
    }
};

It works but it does not look to me like a safe solution for the following reasons:

1. I change and add elements to the JFrame from another thread.
2. I add a new JPanel to a JFrame, after I have already "packed" the JFrame and made it visible.

Should I be doing that?

setVisible(false), even in the correct place, will not actually remove the panel from the container. If you want to replace the panel do this:

frame.getContentPane().remove(partnerSelectionPanel);
frame.add(new JPanel());
frame.getContentPane().invalidate();
frame.getContentPane().validate();

Note that frame.getContentPane().add(Component) is the same as frame.add(Component) - the components are actually contained within the content pane.

Don't forget or overlook the approach of using the Layout, namely the CardLayout as the Frames Layout, to allow this type of behavior (This is a good strategy for a "Wizard" for example). One advantage to this is it doesn't cause any weird flash or draw effects as that is what this Layout is meant to do--Allow a panels to be swapped out, assuming they have exclusive "real estate" or can share the same areas (i.e. "Wizard" like behavior.)

You can use

  Frame.setContentPane(jPanel);

partnerSelectionPanel.setVisible(false); \\ <------------

This line is actualy out the method run.

You probably want something like this:

public void run() {
   label.setText(i + " seconds left.");
   try {
      Thread.sleep (i * 1000);
   } catch (InterruptedException e) {
      handleException (e);
   }
   partnerSelectionPanel.setVisible(false);
}