SWING - JProgressBar Class

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Introduction

The class JProgressBar is a component which visually displays the progress of some task.

Class Declaration

Following is the declaration for javax.swing.JProgressBar class −

public class JProgressBar
   extends JComponent
      implements SwingConstants, Accessible

Field

Following are the fields for javax.swing.JProgressBar class −

• protected ChangeEvent changeEvent − Only one ChangeEvent is needed per instance since the event's only interesting property is the immutable source, which is the progress bar.

• protected ChangeListener changeListener − Listens for change events sent by the progress bar's model, redispatching them to change-event listeners registered upon this progress bar.

• protected BoundedRangeModel model − The object that holds the data for the progress bar.

• protected int orientation − Whether the progress bar is horizontal or vertical.

• protected boolean paintBorder − Whether to display a border around the progress bar.

• protected boolean paintString − Whether to display a string of text on the progress bar.

• protected String progressString − An optional string that can be displayed on the progress bar.

Class Constructors

Class Methods

Methods Inherited

This class inherits methods from the following classes −

• javax.swing.JComponent
• java.awt.Container
• java.awt.Component
• java.lang.Object

JProgressBar Example

Create the following Java program using any editor of your choice in say D:/ > SWING > com > tutorialspoint > gui >

SwingControlDemo.java

package com.tutorialspoint.gui;
 
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
 
public class SwingControlDemo {
   private JFrame mainFrame;
   private JLabel headerLabel;
   private JLabel statusLabel;
   private JPanel controlPanel;
   
   public SwingControlDemo(){
      prepareGUI();
   }
   public static void main(String[] args){
      SwingControlDemo  swingControlDemo = new SwingControlDemo();      
      swingControlDemo.showProgressBarDemo();
   }
   private void prepareGUI(){
      mainFrame = new JFrame("Java Swing Examples");
      mainFrame.setSize(400,400);
      mainFrame.setLayout(new GridLayout(3, 1));
      
      mainFrame.addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent windowEvent){
            System.exit(0);
         }        
      });    
      headerLabel = new JLabel("", JLabel.CENTER);        
      statusLabel = new JLabel("",JLabel.CENTER);    
      statusLabel.setSize(350,100);

      controlPanel = new JPanel();
      controlPanel.setLayout(new FlowLayout());

      mainFrame.add(headerLabel);
      mainFrame.add(controlPanel);
      mainFrame.add(statusLabel);
      mainFrame.setVisible(true);  
   }
   private JProgressBar progressBar;
   private Task task;
   private JButton startButton;
   private JTextArea outputTextArea;
   
   private void showProgressBarDemo(){
      headerLabel.setText("Control in action: JProgressBar"); 
      progressBar = new JProgressBar(0, 100);
      progressBar.setValue(0);
      progressBar.setStringPainted(true);
      startButton = new JButton("Start");
      outputTextArea = new JTextArea("",5,20);
      JScrollPane scrollPane = new JScrollPane(outputTextArea);    
      
      startButton.addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
            task = new Task();                
            task.start();
         }
      });
      controlPanel.add(startButton);
      controlPanel.add(progressBar);
      controlPanel.add(scrollPane);
      mainFrame.setVisible(true);  
   }
   private class Task extends Thread {    
      public Task(){
      }
      public void run(){
         for(int i =0; i<= 100; i+=10){
            final int progress = i;
            
            SwingUtilities.invokeLater(new Runnable() {
               public void run() {
                  progressBar.setValue(progress);
                  outputTextArea.setText(outputTextArea.getText() 
                     + String.format("Completed %d%% of task.\n", progress));
               }
            });
            try {
               Thread.sleep(100);
            } catch (InterruptedException e) {}
         }
      }
   }   
}

Compile the program using the command prompt. Go to D:/ > SWING and type the following command.

D:\SWING>javac com\tutorialspoint\gui\SwingControlDemo.java

If no error occurs, it means the compilation is successful. Run the program using the following command.

D:\SWING>java com.tutorialspoint.gui.SwingControlDemo

Verify the following output.