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;
            }
      }
   }
}