SWING - ItemListener Interface


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The class which processes the ItemEvent should implement this interface.The object of that class must be registered with a component. The object can be registered using the addItemListener() method. When the action event occurs, that object's itemStateChanged method is invoked.

Interface Declaration

Following is the declaration for java.awt.event.ItemListener interface −

public interface ItemListener
   extends EventListener

Interface Methods

Sr.No. Method & Description
1

void itemStateChanged(ItemEvent e)

Invoked when an item has been selected or deselected by the user.

Methods Inherited

This interface inherits methods from the following interfaces −

  • java.awt.EventListener

ItemListener Example

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

SwingListenerDemo.java

package com.tutorialspoint.gui;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class SwingListenerDemo {
   private JFrame mainFrame;
   private JLabel headerLabel;
   private JLabel statusLabel;
   private JPanel controlPanel;

   public SwingListenerDemo(){
      prepareGUI();
   }
   public static void main(String[] args){
      SwingListenerDemo  swingListenerDemo = new SwingListenerDemo();  
      swingListenerDemo.showItemListenerDemo();
   }
   private void prepareGUI(){
      mainFrame = new JFrame("Java SWING Examples");
      mainFrame.setSize(400,400);
      mainFrame.setLayout(new GridLayout(3, 1));

      headerLabel = new JLabel("",JLabel.CENTER );
      statusLabel = new JLabel("",JLabel.CENTER);        
      statusLabel.setSize(350,100);
      
      mainFrame.addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent windowEvent){
            System.exit(0);
         }        
      });    
      controlPanel = new JPanel();
      controlPanel.setLayout(new FlowLayout());

      mainFrame.add(headerLabel);
      mainFrame.add(controlPanel);
      mainFrame.add(statusLabel);
      mainFrame.setVisible(true);  
   }
   private void showItemListenerDemo(){
      headerLabel.setText("Listener in action: ItemListener");      
      JCheckBox chkApple = new JCheckBox("Apple");
      JCheckBox chkMango = new JCheckBox("Mango");
      JCheckBox chkPeer = new JCheckBox("Peer");
   
      chkApple.addItemListener(new CustomItemListener());
      chkMango.addItemListener(new CustomItemListener());
      chkPeer.addItemListener(new CustomItemListener());

      controlPanel.add(chkApple);
      controlPanel.add(chkMango);
      controlPanel.add(chkPeer);               
      mainFrame.setVisible(true); 
   }
   class CustomItemListener implements ItemListener {
      public void itemStateChanged(ItemEvent e) {
         statusLabel.setText(((JCheckBox)e.getItem()).getText()
            +" Checkbox: " + (e.getStateChange()==1?"checked":"unchecked"));
      }    
   }
}

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

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

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

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

Verify the following output.

SWING ItemListener
swing_event_listeners.htm

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