Java----如何在窗口中创建菜单

package stu1;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.lang.*;
public class menu {
    public static class MainForm extends JFrame {


        private void init(String title)
        {
            setTitle(title);//设置窗口标题


            JMenuBar menuBar = new JMenuBar();//创建菜单栏对象
            setJMenuBar(menuBar);// 将菜单栏对象添加到窗体的菜单栏中

            JMenu menu1 = new JMenu("菜单1");// 创建菜单对象
            menuBar.add(menu1);//将菜单对象添加到菜单栏对象中
            JMenuItem item1 = new JMenuItem("菜单选项1");//创建子菜单对象
            menu1.add(item1);//将子菜单对象添加到一级菜单对象中


            menu1.addSeparator();//在菜单项中间添加分界线

            JMenu menu2 = new JMenu("菜单2");
            menuBar.add(menu2);
            JMenuItem item2 = new JMenuItem("菜单选项2");
            menu1.add(item2);


            JMenu submenu = new JMenu("子菜单1");
            menu1.add(submenu);
            submenu.add(new JMenuItem("子菜单1"));
            submenu.add(new JMenuItem("子菜单2"));



            //item1.setAccelerator(KeyStroke.getKeyStroke(‘A‘));
            item1.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_S,KeyEvent.CTRL_MASK));//添加热键




        }
        public MainForm(String title,int posX,int posY,int width,int height)
        {
            init(title);
            setLocation(posX,posY);
            setSize(width,height);
            setVisible(true);
            setResizable(true);

        }

        public static void main(String[] args){
            int x=0,y=0,w=1000,h=1000;
            MainForm windows1 = new MainForm("一个小窗",x,y,w,h);
            MainForm windows2 = new MainForm("一个小小窗",x,y,w,h);
            Container container= windows1.getContentPane();
            container.setBackground(Color.darkGray);

            windows1.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            windows2.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);

        }
    }
}