Developing the optimal GUI

Question

Hi all,
I am developing a program with a main window that appears at run. From there, the user can click on one of two buttons to tell the program which type of calculation he would like to perform. I am okay up to that point, no problem.
The next part of the program will have:
1. Screen where user sees a combo box and button
2. After hitting OK, user will see a larger screen that uses the combo box to determine the number of text fields the user will enter data in
3. After entering the data, different calculations will take place and different screens will display results using graphs or just text.
I was wondering, if between the different cards, would I be able to change the window size even if they went to the previous card? It would be pointless to have a combo box on a window the size 800 x 600, but 800 x 600 may be ideal for the next screen.
I've tried getPreferredSize() and had nothing but problems with it. Maybe I shouldn't use CardLayout? Or use JOptionPane for the first window, then use the cards for the rest of the program. Any ideas, suggestions, or help would be greatly appreciated.

Answer 1

Here is an example:
public class CopyDialog  extends JDialog implements ActionListener{
     private JTextArea dataArea= new JTextArea();
     /*Constructor*/
     public CopyDialog(JFrame parent){
          super(parent, "Copy", true);
          JButton ok = new JButton("OK");
          ok.addActionListener(this);
          JPanel buttonPanel = new JPanel();
          buttonPanel.add(ok);
          JPanel content = new JPanel(new BorderLayout());
          content.add(new JLabel("Enter data:"),
                    BorderLayout.PAGE_START);
          content.add(new JScrollPane(dataArea), BorderLayout.CENTER);
          content.add(buttonPanel, BorderLayout.PAGE_END);
          setContentPane(content);
          setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
          setSize(new Dimension(450,300));
          setLocationRelativeTo(parent);
          setVisible(true);
     public void actionPerformed(ActionEvent arg0) {
          setVisible(false);
     public List<String> getData(){
          return dataArea.getText();
}