Java Popup Menu

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

public class PopupTest extends JFrame
     {
     private JRadioButtonMenuItem items[];
     private Color colorValues[] = { Color.blue, Color.yellow, Color.red };
  
     public PopupTest()
         {
         super( "Using JPopupMenus" );
      
         final JPopupMenu popupMenu = new JPopupMenu();
         ItemHandler handler = new ItemHandler();
         String colors[] = { "Blue", "Yellow", "Red" };
         ButtonGroup colorGroup = new ButtonGroup();
         items = new JRadioButtonMenuItem[ 3 ];
      
         // construct each menu item and add to popup menu; also
         // enable event handling for each menu item
         for ( int i = 0; i < items.length; i++ )
             {
             items[ i ] = new JRadioButtonMenuItem( colors[ i ] );
             popupMenu.add( items[ i ] );
             colorGroup.add( items[ i ] );
             items[ i ].addActionListener( handler );
         }
      
         getContentPane().setBackground( Color.white );
      
         // define a MouseListener for the window that displays
         // a JPopupMenu when the popup trigger event occurs
         addMouseListener( new MouseAdapter()
             {
             public void mousePressed( MouseEvent e )
                 {
                 checkForTriggerEvent( e );
             }
          
             public void mouseReleased( MouseEvent e )
                 {
                 checkForTriggerEvent( e );
             }
          
             private void checkForTriggerEvent( MouseEvent e )
                 {
                 if ( e.isPopupTrigger() )
                 popupMenu.show( e.getComponent(), e.getX(), e.getY() );
             }
         } );
      
         setSize( 300, 200 );
         show();
     }
  
     public static void main( String args[] )
         {
         PopupTest app = new PopupTest();
      
         app.addWindowListener( new WindowAdapter()
             {
             public void windowClosing( WindowEvent e )
                 {
                 System.exit( 0 );
             }
         });
     }
  
     private class ItemHandler implements ActionListener
         {
         public void actionPerformed( ActionEvent e )
             {
             // determine which menu item was selected
             for ( int i = 0; i < items.length; i++ )
             if ( e.getSource() == items[ i ] )
                 {
                 getContentPane().setBackground( colorValues[ i ] );
                 repaint();
                 return;
             }
         }
     }
}