JFrame on applet

Here a code to make JFrame on applet,This program demonstrates the basics of creating a frame user interface with a menubar. It also shows how to add a menubar and dropdown menus to the applet, which wasn't possible in the basic AWT heavyweight component.
java code

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

/**
  * This program demonstrates the basics of creating a frame
  * user interface with a menubar. It also shows how to
  * add a menubar and dropdown menus to the applet, which wasn't
  * possible in the basic AWT heavyweight component.
 **/
public class FrameApplet extends JApplet
       implements ActionListener
{
  JFrame fFrame;
  JMenuItem fMenuClose ;
  JMenuItem fMenuOpen;

  /** Build an applet interface with a menubar. A
    * a drop down menu includes Open/Close items
    * for opening and closing an instance of ParticleFrame.
   **/
  public void init () {
    JMenuBar mb = new JMenuBar ();
    JMenu m = new JMenu ("File");
    fMenuOpen= new JMenuItem ("Open");
    m.add (fMenuOpen);
    fMenuOpen.addActionListener (this);

    fMenuClose = new JMenuItem ("Close");
    m.add (fMenuClose);
    fMenuClose.addActionListener (this);
    mb.add (m);

    setJMenuBar (mb);

    fFrame = new ParticleFrame (this);
    fFrame.setVisible (true);
    fMenuOpen.setEnabled (false);
    fMenuClose.setEnabled (true);

  } // init

  /** Get the menu events here. Open an instance of ParticleFrame
    * or close the one currently displayed.
   **/
  public void actionPerformed (ActionEvent e) {
    String command = e.getActionCommand ();
    if (command.equals ("Close")) {
        close ();
    } else { // Open
        if (fFrame == null) {
            fFrame = new ParticleFrame (this);
            fFrame.setVisible (true);
            fMenuOpen.setEnabled (false);
            fMenuClose.setEnabled (true);
        }
    }
  } // actionPerformed

  /** Close the frame. **/
  void close () {
    fFrame.dispose ();
    fFrame = null;
    fMenuOpen.setEnabled (true);
    fMenuClose.setEnabled (false);
  } // close

} // class FrameApplet


/** A JFrame subclass that displays a menu bar
  * and a JComboBox.
 **/
class ParticleFrame extends JFrame
                    implements ActionListener, ItemListener
{
  JLabel fLabelA;
  JLabel fLabelB;

  FrameApplet fApplet;

  ParticleFrame (FrameApplet applet) {
    super ("Frame Test");

    fApplet = applet;
    Container content_pane = getContentPane ();

    content_pane.setLayout (new GridLayout (1,3));

    JPanel choice_panel = new JPanel ();
    choice_panel.add (new JLabel ("Quark", JLabel.RIGHT) );

    JComboBox c = new JComboBox ();
    c.addItem ("Up");
    c.addItem ("Down");
    c.addItem ("Strange");
    c.addItem ("Charm");
    c.addItem ("Top");
    c.addItem ("Bottom");
    c.addItemListener (this);
    choice_panel.add (c);

    content_pane.add (choice_panel);

    fLabelA =new JLabel ("Quark: Up");
    content_pane.add (fLabelA);
    fLabelB =new JLabel ("Lepton: Electron");
    content_pane.add (fLabelB);

    // Use the helper method makeMenuItem
    // for making the menu items and registering
    // their listener.
    JMenu m = new JMenu ("Lepton");
    m.add (makeMenuItem ("electron"));
    m.add (makeMenuItem ("muon"));
    m.add (makeMenuItem ("tau"));

    JMenu sm = new JMenu ("Neutrino");
    sm.add (makeMenuItem ("e Neutrino"));
    sm.add (makeMenuItem ("mu Neutrino"));
    sm.add (makeMenuItem ("tau Neutrino"));

    m.add (sm);
    m.add (makeMenuItem ("Quit"));
    JMenuBar mb = new JMenuBar ();
    mb.add (m);

    setJMenuBar (mb);
    setSize (200,200);
    pack ();
    setDefaultCloseOperation (JFrame.DISPOSE_ON_CLOSE);
  } // ctor

  /** Get the combobox item events here. **/
  public void itemStateChanged (ItemEvent e) {
    String command = e.getItem ().toString ();
    if (command.equals ("Quit") )
        dispose ();
    else
        fLabelA.setText ("Quark: " + command);
  } // itemStateChanged

  /** Get the menu events here. **/
  public void actionPerformed (ActionEvent e) {
    String command = e.getActionCommand ();
    if (command.equals ("Quit")) {
        fApplet.close ();
    } else {
        fLabelB.setText ("Lepton: " + command);
    }
  } // actionPerformed

  /** This "helper method" makes a menu item and then
    * registers this applet as a listener to it.
   **/
  private JMenuItem makeMenuItem (String name) {
    JMenuItem m = new JMenuItem (name);
    m.addActionListener (this);
    return m;
  } // makeMenuItem

} // class ParticleFrame