SWING - JButton Class


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Introduction

The class JButton is an implementation of a push button. This component has a label and generates an event when pressed. It can have Image also.

Class declaration

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

public class JButton
   extends AbstractButton
      implements Accessible

Class constructors

S.N. Constructor & Description
1 JButton()

Creates a button with no set text or icon.

2 JButton(Action a)

Creates a button where properties are taken from the Action supplied.

3 JButton(Icon icon)

Creates a button with an icon.

4 JButton(String text)

Creates a button with text.

5 JButton(String text, Icon icon)

Creates a button with initial text and an icon.

Class methods

S.N. Method & Description
1 AccessibleContext getAccessibleContext()

Gets the AccessibleContext associated with this JButton.

2 String getUIClassID()

Returns a string that specifies the name of the L&F class that renders this component.

3 boolean isDefaultButton()

Gets the value of the defaultButton property, which if true means that this button is the current default button for its JRootPane.

4 boolean isDefaultCapable()

Gets the value of the defaultCapable property.

5 protected String paramString()

Returns a string representation of this JButton.

6 void removeNotify()

Overrides JComponent.removeNotify to check if this button is currently set as the default button on the RootPane, and if so, sets the RootPane's default button to null to ensure the RootPane doesn't hold onto an invalid button reference.

7 void setDefaultCapable(boolean defaultCapable)

Sets the defaultCapable property, which determines whether this button can be made the default button for its root pane.

8 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.AbstractButton

  • javax.swing.JComponent

  • java.awt.Container

  • java.awt.Component

  • java.lang.Object

JButton 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.showButtonDemo();
   }

   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 static ImageIcon createImageIcon(String path, 
      String description) {
      java.net.URL imgURL = SwingControlDemo.class.getResource(path);
      if (imgURL != null) {
         return new ImageIcon(imgURL, description);
      } else {            
         System.err.println("Couldn't find file: " + path);
         return null;
      }
   }   

   private void showButtonDemo(){

      headerLabel.setText("Control in action: Button"); 

      //resources folder should be inside SWING folder.
      ImageIcon icon = createImageIcon("/resources/java_icon.png","Java");

      JButton okButton = new JButton("OK");        
      JButton javaButton = new JButton("Submit", icon);
      JButton cancelButton = new JButton("Cancel", icon);
      cancelButton.setHorizontalTextPosition(SwingConstants.LEFT);   

      okButton.addActionListener(new ActionListener() {
         public void actionPerformed(ActionEvent e) {
            statusLabel.setText("Ok Button clicked.");
         }          
      });

      javaButton.addActionListener(new ActionListener() {
         public void actionPerformed(ActionEvent e) {
            statusLabel.setText("Submit Button clicked.");
         }
      });

      cancelButton.addActionListener(new ActionListener() {
         public void actionPerformed(ActionEvent e) {
            statusLabel.setText("Cancel Button clicked.");
         }
      });

      controlPanel.add(okButton);
      controlPanel.add(javaButton);
      controlPanel.add(cancelButton);       

      mainFrame.setVisible(true);  
   }
}

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

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

If no error comes that means compilation is successful. Run the program using following command.

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

Verify the following output

Swing JButton
swing_controls.htm

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