In this topic, we will discuss ItemListener in the AWT 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
| S.N. | 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:/ > AWT > com > adglob > gui >AwtListenerDemo.java
package com.adglob.gui;
import java.awt.*;
import java.awt.event.*;
public class AwtListenerDemo {
private Frame mainFrame;
private Label headerLabel;
private Label statusLabel;
private Panel controlPanel;
public AwtListenerDemo(){
prepareGUI();
}
public static void main(String[] args){
AwtListenerDemo awtListenerDemo = new AwtListenerDemo();
awtListenerDemo.showItemListenerDemo();
}
private void prepareGUI(){
mainFrame = new Frame("Java AWT 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 Label();
headerLabel.setAlignment(Label.CENTER);
statusLabel = new Label();
statusLabel.setAlignment(Label.CENTER);
statusLabel.setSize(350,100);
controlPanel = new Panel();
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");
Checkbox chkApple = new Checkbox("Apple");
Checkbox chkMango = new Checkbox("Mango");
Checkbox chkPeer = new Checkbox("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(e.getItem()
+" Checkbox: "
+ (e.getStateChange()==1?"checked":"unchecked"));
}
}
}
Compile the program using command prompt. Go to D:/ > AWT and type the following command.
D:\AWT>javac com\adglob\gui\AwtListenerDemo.java
If no error comes that means compilation is successful. Run the program using following command.
D:\AWT>java com.adglob.gui.AwtListenerDemo
Verify the following output
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