Update JPanel in JDialog

Question

Hey,
need some help please....
I've searched long and hard but can't find anything.
I've got an application that opens a JDialog, then jDialog has a JPanel within
it.
Once the JDialog has loaded on the screen i want to update the Jpanel based on
a button click.
My problem is that the JPanel wont update.
I've made a simple program that displays the same behaviour.
Frame with a button on it to open a JDialog :
public class testFrame extends javax.swing.JFrame {
    /** Creates new form testFrame */
    public testFrame() {
        initComponents();
    /** This method is called from within the constructor to
     * initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is
     * always regenerated by the Form Editor.
    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {
        jButton1 = new javax.swing.JButton();
        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        jButton1.setText("Show Dialog");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(150, 150, 150)
                .addComponent(jButton1)
                .addContainerGap(159, Short.MAX_VALUE))
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(135, 135, 135)
                .addComponent(jButton1)
                .addContainerGap(142, Short.MAX_VALUE))
        pack();
    }// </editor-fold>
    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
        // TODO add your handling code here:
        testJDialog test = new testJDialog(this,true);
        test.setVisible(true);
     * @param args the command line arguments
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new testFrame().setVisible(true);
    // Variables declaration - do not modify
    private javax.swing.JButton jButton1;
    // End of variables declaration
}JDialog code :
import javax.swing.JTree;
* @author  wesley
public class testJDialog extends javax.swing.JDialog {
    /** Creates new form testJDialog */
    public testJDialog(java.awt.Frame parent, boolean modal) {
        super(parent, modal);
        initComponents();
    /** This method is called from within the constructor to
     * initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is
     * always regenerated by the Form Editor.
    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {
        jPanel1 = new javax.swing.JPanel();
        jButton1 = new javax.swing.JButton();
        setDefaultCloseOperation(javax.swing.WindowConstants.DISPOSE_ON_CLOSE);
        jPanel1.setBorder(javax.swing.BorderFactory.createTitledBorder("TitleBorder"));
        javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
        jPanel1.setLayout(jPanel1Layout);
        jPanel1Layout.setHorizontalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 347, Short.MAX_VALUE)
        jPanel1Layout.setVerticalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 128, Short.MAX_VALUE)
        jButton1.setText("Add Tree");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(layout.createSequentialGroup()
                        .addContainerGap()
                        .addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                    .addGroup(layout.createSequentialGroup()
                        .addGap(145, 145, 145)
                        .addComponent(jButton1)))
                .addContainerGap(31, Short.MAX_VALUE))
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(18, 18, 18)
                .addComponent(jButton1)
                .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
        pack();
    }// </editor-fold>
    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
        // TODO add your handling code here:
        this.jPanel1.add(new JTree());
        this.pack();
        this.repaint();
     * @param args the command line arguments
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                testJDialog dialog = new testJDialog(new javax.swing.JFrame(), true);
                dialog.addWindowListener(new java.awt.event.WindowAdapter() {
                    public void windowClosing(java.awt.event.WindowEvent e) {
                        System.exit(0);
                dialog.setVisible(true);
    // Variables declaration - do not modify
    private javax.swing.JButton jButton1;
    private javax.swing.JPanel jPanel1;
    // End of variables declaration
}Ive tried
this.pack();
this.repaint();but i cant get the JPanel to repaint.
Im using Vista Java version
C:\Users\wesley>java -version
java version "1.6.0_03"
Java(TM) SE Runtime Environment (build 1.6.0_03-b05)
Java HotSpot(TM) Client VM (build 1.6.0_03-b05, mixed mode, sharing)Cheers
Wesley

Answer 1

wesleyelder wrote:
Thanks so much for taking the time to reply, that worked a treat.you're welcome
i agree the netbeans code is a mess sometimes but when i just need a simple JDialog i sometimes use it, just lazy a guess :)But then you run into problems like this one. I'd much prefer to make my own simple JDialog:
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTree;
public class TestMyDialog
    private JPanel mainPanel = new JPanel();
    private JPanel centerPanel = new JPanel();
    public TestMyDialog()
        JButton addTreeBtn = new JButton("Add Tree");
        addTreeBtn.addActionListener(new ActionListener()
            public void actionPerformed(ActionEvent e)
                addTreeAction();
        JPanel buttonPanel = new JPanel();
        buttonPanel.add(addTreeBtn);
        centerPanel.setBorder(BorderFactory.createTitledBorder("Title Border"));
        centerPanel.setPreferredSize(new Dimension(400, 200));
        centerPanel.setLayout(new BorderLayout());
        mainPanel.setBorder(BorderFactory.createEmptyBorder(15, 15, 15, 15));
        mainPanel.setLayout(new BorderLayout(20, 20));
        mainPanel.add(centerPanel, BorderLayout.CENTER);
        mainPanel.add(buttonPanel, BorderLayout.SOUTH);
    private void addTreeAction()
        JTree tree = new JTree();
        tree.setOpaque(false);
        centerPanel.add(new JScrollPane(tree), BorderLayout.CENTER);
        centerPanel.revalidate();
    public JPanel getMainPanel()
        return mainPanel;
    private static void createAndShowUI()
        final JFrame frame = new JFrame("Test My Dialog");
        JPanel framePanel = new JPanel();
        framePanel.setBorder(BorderFactory.createEmptyBorder(200, 200, 200, 200));
        framePanel.setPreferredSize(new Dimension(500, 500));
        JButton showDialogBtn = new JButton("Show Dialog");
        showDialogBtn.addActionListener(new ActionListener()
            public void actionPerformed(ActionEvent e)
                showDialogAction(frame);
        framePanel.add(showDialogBtn);
        frame.getContentPane().add(framePanel);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    private static void showDialogAction(JFrame frame)
        JDialog dialog = new JDialog(frame, "My Dialog", true);
        dialog.getContentPane().add(new TestMyDialog().getMainPanel());
        dialog.pack();
        dialog.setLocationRelativeTo(null);
        dialog.setVisible(true);
    public static void main(String[] args)
        java.awt.EventQueue.invokeLater(new Runnable()
            public void run()
                createAndShowUI();
}