jprogressbar visible and working on button click

Question

public NewJDialog(java.awt.Frame parent, boolean modal) {
    super(parent, modal);
    initComponents();
  jProgressBar1.setVisible(false);

}  

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                     
    jButton1.setEnabled(false);
    jProgressBar1.setVisible(true);        
   repaint();            
   for(int i=0;i<=100;i+=5){
          jProgressBar1.setValue(i);
         // jProgressBar1.setIndeterminate(false);              
          try{
              jProgressBar1.paintImmediately(0, 0, 100, 100);//0, 1, 100, 10
          Thread.sleep(100);
          jProgressBar1.setStringPainted(true);

     }catch(Exception e){}
    }

I use above code for using a Jprogressbar in a JDialog. If I use this I can see a progressbar after completing its process(100 %) and also I don't want to show the progressbar upto buttonclick.

Answer 1

1. Use a separate Thread for running your task. The progress bar doesn't have a chance to get painted on the GUI thread. You need something like SwingWorker to help you out.
2. Add the progress bar to the GUI after the button click.
3. Refer to the Java tutorial for a walk through on how to set it up.

Answer 2

//Simplest way of using JProgressBar

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.sql.*;
import java.util.*;
class logindemo extends JFrame implements ActionListener
   {
      JProgressBar pb;
      JButton b1;
          logindemo()
          {
             super("LOGIN FORM");
             setLayout(null);
             b1=new JButton("LOGIN");
             b1.setBackground(Color.yellow);             
             pb=new JProgressBar(1,100);
             pb.setValue(0);
             pb.setStringPainted(true);
             pb.setForeground(Color.red);   
             pb.setBackground(Color.white); 
             b1.setBounds(20,20,80,25);pb.setBounds(110,20,200,25);
             pb.setVisible(false);
             add(b1);
             add(pb);             
             b1.addActionListener(this);
             setResizable(false);
             setDefaultCloseOperation(EXIT_ON_CLOSE);
          }
           public void actionPerformed(ActionEvent e)
           {
              int i=0;
              if(e.getSource()==b1)
                 {
                   pb.setVisible(true);
                try
                {
                   while(i<=100)
                   {
                    Thread.sleep(50);
    pb.paintImmediately(0, 0, 200, 25);
        pb.setValue(i);
                     i++;
    }
                 }
                 catch(Exception e1)
                 {
    System.out.print("Caughted exception is ="+e1);
                 }
                }
           }
          public static void main(String arg[])
          {
          logindemo m=new logindemo();
          m.setSize(330,100);
          m.setVisible(true);
          Dimension dimension = Toolkit.getDefaultToolkit().getScreenSize();
          int x = (int) ((dimension.getWidth() - m.getWidth()) / 2);
          int y = (int) ((dimension.getHeight() - m.getHeight()) / 2);
          m.setLocation(x, y); 
          }
   }

/* 
By 
Dr. Amit Kumar Kapoor
Assistant Professor, Maharaja Agrasen Institute of Management & Technology, Jagadhri
E-mail ID: - akbrightfuture@gmail.com
*/