Change JFrame content pane without window resizing

[Jon Brasted]

Hi.

Inside a JFrame's container, I have a JPanel. I have a JScrollPane inside that which currently has a JTextArea object. Using a menu item, I want to be able to change the contents of the scroll pane to a JTree. I can currently do it by getting the JPanel and then adding a new JScollPane object containing the JTree. However, when I do so, the frame shrinks and then (nearly) instantly resizes. I want the frame to 'stay put'.

Is there any way of doing this?

Thanks,
Jon

[Michael Dunn]

can you post a sample program, similar to below, showing the problem.

simple demo from your description, seems to work OK

    
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
class Testing
{
  public void buildGUI()
  {
    JPanel p = new JPanel(new BorderLayout());
    final JScrollPane sp = new JScrollPane(new JTextArea("Hello World",10,10));
    JButton btn = new JButton("Change scrollPane");
    p.add(sp,BorderLayout.CENTER);
    p.add(btn,BorderLayout.SOUTH);
    JFrame f = new JFrame();
    f.getContentPane().add(p);
    f.setSize(150,150);
    f.setLocationRelativeTo(null);
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.setVisible(true);
    btn.addActionListener(new ActionListener(){
      public void actionPerformed(ActionEvent ae){
        sp.setViewportView(new JTree());
      }
    });
  }
  public static void main(String[] args)
  {
    SwingUtilities.invokeLater(new Runnable(){
      public void run(){
        new Testing().buildGUI();
      }
    });
  }
}