MenuItemActionListenerTest.java - AWT Menu Item Action Listener

Java Swing Tutorials - Herong's Tutorial Examples

∟MenuItemActionListenerTest.java - AWT Menu Item Action Listener

This section provides a tutorial example on how to use java.awt.event.ActionListener, button action listener interface, to catch events fired by MenuItem objects.

Like any other user interface components, MenuItem objects also fire events when users interact with them. If you want to perform a task when an event occurs on a MenuItem object, you need to add an event listener to that MenuItem item object. Because a MenuItem is a sub class of AbstractButton, it shares the listener interface and event class with AbstractButton:

java.awt.event.ActionListener - An AWT interface that allows you to implement your own event handler methods:

actionPerformed(ActionEvent) - Event handler method called when the associated component is clicked. You need to implement this method to perform your own task.

java.awt.event.ActionEvent - An AWT class that represents an event occurred on a component. The most important method in this class is:

getActionCommand() - Method returns the action command string.

Here is an example program I wrote to test the ActionListener interface:

/* MenuItemActionListenerTest.java
 * Copyright (c) 1997-2024 HerongYang.com. All Rights Reserved.
 */
import java.awt.Frame;
import java.awt.MenuBar;
import java.awt.Menu;
import java.awt.MenuItem;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class MenuItemActionListenerTest {
   Frame myFrame = null;
   public static void main(String[] a) {
      (new MenuItemActionListenerTest()).test();
   }
   private void test() {
      myFrame = new Frame("Menu Listener Test");
      myFrame.setBounds(50,50,250,150);

      MenuBar myMenuBar = new MenuBar();
      Menu myMenu = getFileMenu();
      myMenuBar.add(myMenu);
      myMenu = getColorMenu();
      myMenuBar.add(myMenu);
      myMenu = getOptionMenu();
      myMenuBar.add(myMenu);

      myFrame.setMenuBar(myMenuBar);
      myFrame.setVisible(true);
   }
   private Menu getFileMenu() {
      Menu myMenu = new Menu("File");
      MyMenuItem myItem = new MyMenuItem("Open");
      myMenu.add(myItem);
      myItem = new MyMenuItem("Close");
      myMenu.add(myItem);
      myMenu.addSeparator();
      myItem = new MyMenuItem("Exit");
      myMenu.add(myItem);
      return myMenu;
   }
   private Menu getColorMenu() {
      Menu myMenu = new Menu("Color");
      MenuItem myItem = new MyMenuItem("Red");
      myMenu.add(myItem);
      myItem = new MyMenuItem("Green");
      myMenu.add(myItem);
      myItem = new MyMenuItem("Blue");
      myMenu.add(myItem);
      return myMenu;
   }
   private Menu getOptionMenu() {
      Menu myMenu = new Menu("Option");
      MenuItem myItem = new MyMenuItem("Sound");
      myMenu.add(myItem);
      myItem = new MyMenuItem("Auto save");
      myMenu.add(myItem);
      return myMenu;
   }
   private class MyMenuItem extends MenuItem 
      implements ActionListener {
      public MyMenuItem(String text) {
         super(text);
         addActionListener(this);
      }
      public void actionPerformed(ActionEvent e) {
         System.out.println("Item clicked: "+e.getActionCommand());
      }
   }
}

If you run this example, you will see the frame window shows up with the menu bar like this:

AWT enu Item Action Listener Test — AWT Menu Item Action Listener Test

If you click the "Help" menu item, click "Open" and "Close" in the "File" menu, then click "Red", "Green" and "Blue" in the "Color" menu, you will see some messages printed on the Java console window:

Item clicked: Help
Item clicked: Open
Item clicked: Close
Item clicked: Red
Item clicked: Green
Item clicked: Blue

Interesting notes about this tutorial example:

"private class MyMenuItem extends MenuItem implements ActionListener" declaration is used to create an inner class, MyMenuItem, which extends MenuItem, implements ActionListener, and adds itself to handle action events.
"addActionListener(this);" statement is used to add my inner class, MyMenuItem, itself to handle action events.
"e.getActionCommand()" expression is used to get action command string, the menu item button text in this case.