SWING - JProgressBar Class

---

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

Sr.No.	Constructor & Description
1	JProgressBar() Creates a horizontal progress bar that displays a border but no progress string.
2	JProgressBar(BoundedRangeModel newModel) Creates a horizontal progress bar that uses the specified model to hold the progress bar's data.
3	JProgressBar(int orient) Creates a progress bar with the specified orientation, which can be either SwingConstants. VERTICAL or SwingConstants.HORIZONTAL.
4	JProgressBar(int min, int max) Creates a horizontal progress bar with the specified minimum and maximum.
5	JProgressBar(int orient, int min, int max) Creates a progress bar using the specified orientation, minimum, and maximum.

Class Methods

Sr.No.	Method & Description
1	void addChangeListener(ChangeListener l) Adds the specified ChangeListener to the progress bar.
2	protected ChangeListener createChangeListener() Subclasses that want to handle change events from the model differently can override this to return an instance of a custom ChangeListener implementation.
3	protected void fireStateChanged() Send a ChangeEvent, whose source is JProgressBar, to all ChangeListeners that have registered interest in ChangeEvents.
4	AccessibleContext getAccessibleContext() Gets the AccessibleContext associated with this JProgressBar.
5	ChangeListener[] getChangeListeners() Returns an array of all the ChangeListeners added to this progress bar with addChangeListener.
6	int getMaximum() Returns the progress bar's maximum value from the BoundedRangeModel.
7	int getMinimum() Returns the progress bar's minimum value from the BoundedRangeModel.
8	BoundedRangeModel getModel() Returns the data model used by this progress bar.
9	int getOrientation() Returns SwingConstants.VERTICAL or SwingConstants.HORIZONTAL, depending on the orientation of the progress bar.
10	double getPercentComplete() Returns the percent complete for the progress bar.
11	String getString() Returns a String representation of the current progress.
12	ProgressBarUI getUI() Returns the look-and-feel object that renders this component.
13	String getUIClassID() Returns the name of the look-and-feel class that renders this component.
14	int getValue() Returns the progress bar's current value from the BoundedRangeModel.
15	boolean isBorderPainted() Returns the borderPainted property.
16	boolean isIndeterminate() Returns the value of the indeterminate property.
17	boolean isStringPainted() Returns the value of the stringPainted property.
18	protected void paintBorder(Graphics g) Paints the progress bar's border if the borderPainted property is true.
19	protected String paramString() Returns a string representation of this JProgressBar.
20	void removeChangeListener(ChangeListener l) Removes a ChangeListener from the progress bar.
21	void setBorderPainted(boolean b) Sets the borderPainted property, which is true if the progress bar should paint its border.
22	void setIndeterminate(boolean newValue) Sets the indeterminate property of the progress bar, which determines whether the progress bar is in determinate or indeterminate mode.
23	void setMaximum(int n) Sets the progress bar's maximum value (stored in the progress bar's data model) to n.
24	void setMinimum(int n) Sets the progress bar's minimum value (stored in the progress bar's data model) to n.
25	void setModel(BoundedRangeModel newModel) Sets the data model used by the JProgressBar.
26	void setOrientation(int newOrientation) Sets the progress bar's orientation to newOrientation, which must be SwingConstants.VERTICAL or SwingConstants.HORIZONTAL.
27	void setString(String s) Sets the value of the progress string.
28	void setStringPainted(boolean b) Sets the value of the stringPainted property, which determines whether the progress bar should render a progress string.
29	void setUI(ProgressBarUI ui) Sets the look-and-feel object that renders this component.
30	void setValue(int n) Sets the progress bar's current value to n.
31	void updateUI() Resets the UI property to a value from the current look and feel.

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.