java menu program

import java.awt.*;
import java.awt.event.*;

public class MainWindow extends Frame {
  public MainWindow() {
    super("Menu Window");
    setSize(400, 400);
    FileMenu fileMenu = new FileMenu(this);
    HelpMenu helpMenu = new HelpMenu(this);
    MenuBar mb = new MenuBar();
    mb.add(fileMenu);
    mb.add(helpMenu);
    setMenuBar(mb);
    addWindowListener(new WindowAdapter() {
      public void windowClosing(WindowEvent e) {
        exit();
      }
    });
  }

  public void exit() {
    setVisible(false);
    dispose();
    System.exit(0);
  }

  public static void main(String args[]) {
    MainWindow w = new MainWindow();
    w.setVisible(true);
  }
}

class FileMenu extends Menu implements ActionListener {
  MainWindow mw; 
  public FileMenu(MainWindow m) {
    super("File");
    mw = m;
    MenuItem mi;
    add(mi = new MenuItem("Open"));
    mi.addActionListener(this);
    add(mi = new MenuItem("Close"));
    mi.addActionListener(this);
    add(mi = new MenuItem("Exit"));
    mi.addActionListener(this);
  }

  public void actionPerformed(ActionEvent e) {
    String item = e.getActionCommand();
    if (item.equals("Exit")) 
      mw.exit();
    else 
      System.out.println("Selected FileMenu " + item);
  }
}

class HelpMenu extends Menu implements ActionListener {
  MainWindow mw; 
  public HelpMenu(MainWindow m) {
    super("Help");
    mw = m;
    MenuItem mi;
    add(mi = new MenuItem("Basics"));
    mi.addActionListener(this);
    add(mi = new MenuItem("Advanced"));
    mi.addActionListener(this);
    addSeparator();
    add(mi = new CheckboxMenuItem("Manual"));
    mi.addActionListener(this);
  
    Menu subMenu = new Menu("Miscellaneous");
    subMenu.add(mi = new MenuItem("Help"));
    mi.addActionListener(this);
    subMenu.add(mi = new MenuItem("Other Option"));
    mi.addActionListener(this);
    add(subMenu);
  }
 
  public void actionPerformed(ActionEvent e) {
    String item = e.getActionCommand();
    if (item.equals("Basics"))
      System.out.println("Basics");
    else if (item.equals("Help")) 
      System.out.println("Help");
  }
}