Help Refreshing JFrame, Validate not working...

Question

Hi,
I've read many post suggesting that calling the JFrame.getContentPane().Validate() should refresh my JFrame and display the modifications made to the components on it, but it doesn't work for me. OK, so i'm creating a login screen where i want to hide 2 combos/2 labels, move the buttons and resize the frame when i click on a button (similar to the Windows Login screen where you can click "Options" to view the Domain Combo). When I hide my comtrols, works perfect, when i want to re-display them, the section of the frame that was hidden does not refresh what was behind it. The Option Button calls the ButtonOptionHandler() function, that's where the Validate() is executed.
Here is the complete code for easier understanding, you can run it and see the effects:
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.JPasswordField;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JPanel;
import javax.swing.SwingConstants;
import javax.swing.ImageIcon;
import java.awt.event.*;
public class screenLogin extends JFrame implements ActionListener {
private static String OK = "OK";
private static String CANCEL = "Cancel";
private static String OPTION = "Option";
private boolean showODBC = false;
     private JLabel lblUser;
     private JLabel lblPass;
     private JLabel lblOraODBC;
     private JLabel lblSqlODBC;
     private JTextField txtUser;
     private JPasswordField txtPass;
     private JComboBox cboOraODBC;
     private JComboBox cboSqlODBC;
     private JButton btnOK;
     private JButton btnCancel;
     private JButton btnOption;
     private JLabel lblImage;
     public screenLogin() {
          InitUI();
     private void InitUI() {
          this.setSize(400,230);
          this.getContentPane().setLayout(null);
          /* Labels */
          lblUser = new JLabel("NorLims User", SwingConstants.RIGHT);
          lblPass = new JLabel("Password", SwingConstants.RIGHT);
          lblOraODBC = new JLabel("Oracle ODBC", SwingConstants.RIGHT);
          lblSqlODBC = new JLabel("SQL Anywhere ODBC", SwingConstants.RIGHT);
          lblUser.setBounds(10, 65, 120, 23);
          lblPass.setBounds(10, 90, 120, 23);
          lblOraODBC.setBounds(10, 115, 120, 23);
          lblSqlODBC.setBounds(10, 140, 120, 23);
          txtUser = new JTextField();
          txtUser.setBounds(140, 65, 100, 20);
          txtPass = new JPasswordField();
          txtPass.setBounds(140, 90, 100, 20);
          txtPass.setEchoChar('*');
          cboOraODBC = new JComboBox();
          cboOraODBC.setBounds(140, 115, 200, 20);
          cboSqlODBC = new JComboBox();
          cboSqlODBC.setBounds(140, 140, 200, 20);
          btnOK = new JButton("OK");
          btnOK.setSize(80, 25);
          btnOK.setActionCommand(OK);
          btnOK.addActionListener(this);
          btnCancel = new JButton("Cancel");
          btnCancel.setSize(80, 25);
          btnCancel.setActionCommand(CANCEL);
          btnCancel.addActionListener(this);
          btnOption = new JButton("Options");
          btnOption.setSize(80, 25);
          btnOption.setActionCommand(OPTION);
          btnOption.addActionListener(this);
          // position Buttons and display labels/combos
          ButtonOptionHandler();
          // I commented this part since you dont have the login.jpg
          //lblImage = new JLabel(new ImageIcon("login.jpg"));
          //lblImage.setBounds(0, 0, 400, 60);
          this.getContentPane().add(lblUser, null);
          this.getContentPane().add(lblPass, null);
          this.getContentPane().add(lblOraODBC, null);
          this.getContentPane().add(lblSqlODBC, null);
          this.getContentPane().add(txtUser, null);
          this.getContentPane().add(txtPass, null);
          this.getContentPane().add(cboOraODBC, null);
          this.getContentPane().add(cboSqlODBC, null);
          this.getContentPane().add(btnOK, null);
          this.getContentPane().add(btnCancel, null);
          this.getContentPane().add(btnOption, null);
          //this.getContentPane().add(lblImage, null);
     public void actionPerformed(ActionEvent e) {
          String cmd = e.getActionCommand();
          if (OK.equals(cmd)) { //Process the OK Button
               ButtonOkHandler();
          } else if (CANCEL.equals(cmd)) {
               ButtonCancelHandler();
          } else if (OPTION.equals(cmd)) {
               ButtonOptionHandler();
     private void ButtonOkHandler() {
          System.out.println("OK Button");
     private void ButtonCancelHandler() {
          System.out.println("Cancel Button");
          System.exit(0);
     private void ButtonOptionHandler() {
          showODBC = !showODBC;     // Toggle the value
          int top = (showODBC ? 165 : 115);          // determine the top for the buttons
          this.setSize(400, (showODBC ? 230 : 180));
          lblOraODBC.setVisible(showODBC);
          lblSqlODBC.setVisible(showODBC);
          cboOraODBC.setVisible(showODBC);
          cboSqlODBC.setVisible(showODBC);     
          btnOK.setLocation(100, top);
          btnCancel.setLocation(180, top);
          btnOption.setLocation(260, top);
          this.getContentPane().validate(); // This dont refresh ?!?
I hope someone can help me with this!
Thanks,
XiNull

Answer 1

First suggestion would be to use a layout manager. Then changing the visibility of components within the layout mgr will cause all the proper resizing, refreshing, etc. to happen for you. You should never have to call validate on your own like that (unless you are doing something really bizarre, which you aren't). Generally null or XY layout managers are more hassle than they are worth (and a maintenance nightmare). Do yourself a favor and learn to use gridbaglayout, etc. While a bit wacky to get used to, you will be glad you spent the time on it.