When we create JDialog inside Thread's run() method it is creating problem

Question

I have application that has feature that mainframe will be locked after three minutes and the time when it is locked it will show other locked dialog.
Now my problem is given below:
I have created one Dialog inside Threads run() method and this thread will execute when mainframe is locked.So what is happening is when mainframe is locked internally Thread is doing its job (its job is to display one dialog) and it is displaying dialog but mainframe is locked and still it is showing that dialog.This should not happen in our application when mainframe is locked nothing should come outside.
simple code sample is given below:
SwingUtilities.invokeLater(new Runnable()
JDailog dlg = new JDialog();
dlg.pack();
dlg.show();
Now when my applications mainframe is locked and thread is doing its job when mainframe is locked and it will show one dialog when its run() method will execute and it showing dialog even though mainframe is locked.This is major issue for me.please help me.
sample code may contain compile errror but this only to give understanding what i am doing actually i cant show my original code.
But show me some work around for this problem.Why dialog is coming outside when mainframe is locked?
Please help me.I cant use delay inside run() method because of performance.
Is there any way to control this behaviour?

Answer 1

public class BackGroundThread extends javax.swing.JFrame implements BackgroundTaskInf {
    boolean isMainWindowActive = false;
    /** Creates new form BackGroundThread */
    public BackGroundThread() {
        initComponents();
        new DBBackgroudProcess(this).start();
    /** 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() {
        jDialog1 = new javax.swing.JDialog();
        jLabel1 = new javax.swing.JLabel();
        jLabel2 = new javax.swing.JLabel();
        jButton1 = new javax.swing.JButton();
        jLabel1.setText("JOB DONE");
        javax.swing.GroupLayout jDialog1Layout = new javax.swing.GroupLayout(jDialog1.getContentPane());
        jDialog1.getContentPane().setLayout(jDialog1Layout);
        jDialog1Layout.setHorizontalGroup(
            jDialog1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jDialog1Layout.createSequentialGroup()
                .addGap(95, 95, 95)
                .addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 65, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(240, Short.MAX_VALUE))
        jDialog1Layout.setVerticalGroup(
            jDialog1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jDialog1Layout.createSequentialGroup()
                .addGap(22, 22, 22)
                .addComponent(jLabel1)
                .addContainerGap(22, Short.MAX_VALUE))
        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        jLabel2.setText("Background work in progess");
        jButton1.setText("unlock");
        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(56, 56, 56)
                .addComponent(jLabel2, javax.swing.GroupLayout.PREFERRED_SIZE, 218, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(126, Short.MAX_VALUE))
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addContainerGap(263, Short.MAX_VALUE)
                .addComponent(jButton1)
                .addGap(74, 74, 74))
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(40, 40, 40)
                .addComponent(jLabel2)
                .addGap(37, 37, 37)
                .addComponent(jButton1)
                .addContainerGap(43, Short.MAX_VALUE))
        pack();
    }// </editor-fold>                       
    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                        
        isMainWindowActive = true;
        backgroundTaskFinished();
     * @param args the command line arguments
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new BackGroundThread().setVisible(true);
    public void backgroundTaskFinished(){
        if(isMainWindowActive) {
            jDialog1.setSize(200,200);
            jDialog1.setVisible(true);
            jLabel2.setText("Task is finished");
    // Variables declaration - do not modify                    
    private javax.swing.JButton jButton1;
    private javax.swing.JDialog jDialog1;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    // End of variables declaration                  
class DBBackgroudProcess extends Thread {
    BackgroundTaskInf infObj;
    public DBBackgroudProcess(BackgroundTaskInf infObj){
        this.infObj = infObj;
    public void run(){
        try{
            // here you can do your backgroudn task
            System.out.println("In BackGroud task");
            Thread.sleep(1000);
            System.out.println("task completed");
            infObj.backgroundTaskFinished();
        }catch(Exception e){
            e.printStackTrace();
interface BackgroundTaskInf{
    public void backgroundTaskFinished();
}