Changing the main frame's center panel

Question

I have a JPanel that I've added to my application's main frame's content pane's center, i.e.
JPanel myPanel = new JPanel ();
mainframe.getContentPane().add (myPanel, BorderLayout.CENTER);
Then, I'd like to change that panel, and I do the following
JPanel myNewPanel = new JPanel();
mainframe.getContentPane().remove(myPanel);
mainframe.getContentPane().add(myNewPanel, BorderLayout.CENTER);
mainframe.pack();
This seems to work except that the call to pack() also resizes my application's window. I'd like the application's window to remain the same size as I change the panel throughout the program. How can I achieve this?
BTW, I'm new to swing and GUI programming, so not sure if my choice of implementation is a good one. Basically, what I want to do is, based on user selection, display the selected item in an "appropriate way". This mean sometimes, I want to use a set of GUI labels while other times I want to use a mix of radio buttons, check boxes, and labels.
Thanks in advance.

Answer 1

Can't you just do frame.getContentPane().revalidate()?No, because using the add(...) method does not remove the original component from the panel. So essentially what you have is two components added to the container with the same bounds. Generally the first component added is the one that gets painted.
So to add a new component to a BorderLayout the code should be something like.
contentPane.add(originalComponent, BorderLayout.CENTER );
contentPane.remove( originalComponent );
contentPane.add(anotherComponent, BorderLayout.CENTER);
contentPane.revalidate();
contentPane.repaint(); // sometimes required