2021-09-23 GUI(菜单)

import java.awt.FlowLayout;
import java.awt.Frame;
import java.awt.Menu;
import java.awt.MenuBar;
import java.awt.MenuItem;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

public class MyMenuDemo {

    private Frame f;
    private MenuBar menuBar;
    private Menu menu, subMenu;
    private MenuItem closeItem, subItem;

    public MyMenuDemo() {
        init();
    }

    private void init() {
        f = new Frame("my window");
        f.setBounds(300, 100, 500, 600);
        f.setLayout(new FlowLayout());
        menuBar = new MenuBar();
        menu = new Menu("文件");
        subMenu = new Menu("子菜单");
        subItem = new MenuItem("子条目");
        closeItem = new MenuItem("退出");
        subMenu.add(subItem);
        menu.add(subMenu);
        menu.add(closeItem);
        menuBar.add(menu);
        MyEvent();
        f.setMenuBar(menuBar);
        f.setVisible(true);
    }

    private void MyEvent() {
        closeItem.addActionListener(e -> System.exit(0));

        f.addWindowListener(new WindowAdapter() {

            @Override
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }

        });
    }

    public static void main(String[] args) {
        new MyMenuDemo();
    }

}