How to use Java GUI programming menu components

Common menu-related components are given in the following table:

Menu component name	Function
MenuBar	Menu bar, container of menu.
Menu	Menu component, container of menu items. It is also a subclass of Menultem, so it can be used as a menu item
PopupMenu	Context menu component (right-click menu component)
Menultem	Menu item component.
CheckboxMenuItem	Checkbox menu item component

The following figure is a common menu-related component integration system diagram ：

Use of menu related components:

1. Prepare menu item components, these components can be MenuItem and its subclass objects

2. Prepare the menu component Menu or PopupMenu (right-click to pop up the submenu), and add the menu item component prepared in the first step;

3. Prepare the menu bar component MenuBar, and add the menu item component prepared in the second step. The good menu component Menu is added;

4. Add the menu bar component prepared in the third step to the window object for display.

Tips:

1. If you want to add a dividing line between menu items in a menu, you only need to call Menu's add (new MenuItem(-)).

2. If you want to associate a shortcut key function with a menu item, you only need to set it when creating the menu item object. For example, to associate the ctrl shift / shortcut key with a menu item, you only need: new MenuItem( "Menu item name", new MenuShortcut(KeyEvent.VK_Q,true);

Case 1:

Use common menu components in awt to complete the effect below

Demo code 1:

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class SimpleMenu {
    //创建窗口
    private Frame frame = new Frame("这里测试菜单相关组件");
    //创建菜单条组件
    private MenuBar menuBar = new MenuBar();
    //创建文件菜单组件
    private Menu fileMenu = new Menu("文件");
    //创建编辑菜单组件
    private Menu editMenu = new Menu("编辑");
    //创建新建菜单项
    private MenuItem newItem = new MenuItem("新建");
    //创建保存菜单项
    private MenuItem saveItem = new MenuItem("保存");
    //创建退出菜单项
    private MenuItem exitItem = new MenuItem("退出");
    //创建自动换行选择框菜单项
    private CheckboxMenuItem autoWrap = new CheckboxMenuItem("自动换行");
    //创建复制菜单项
    private MenuItem copyItem = new MenuItem("复制");
    //创建粘贴菜单项
    private MenuItem pasteItem = new MenuItem("粘贴");
    //创建格式菜单
    private Menu formatMenu = new Menu("格式");
    //创建注释菜单项
    private MenuItem commentItem = new MenuItem("注释");
    //创建取消注释菜单项
    private MenuItem cancelItem = new MenuItem("取消注释");
    //创建一个文本域
    private TextArea ta = new TextArea(6, 40);
    public void init(){
        //定义菜单事件监听器
        ActionListener listener = new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                String command = e.getActionCommand();
                ta.append("单击“"+command+"”菜单\n");
                if (command.equals("退出")){
                    System.exit(0);
                }
            }
        };
        //为注释菜单项和退出菜单项注册监听器
        commentItem.addActionListener(listener);
        exitItem.addActionListener(listener);
        //为文件菜单fileMenu添加菜单项
        fileMenu.add(newItem);
        fileMenu.add(saveItem);
        fileMenu.add(exitItem);
        //为编辑菜单editMenu添加菜单项
        editMenu.add(autoWrap);
        editMenu.add(copyItem);
        editMenu.add(pasteItem);
        //为格式化菜单formatMenu添加菜单项
        formatMenu.add(commentItem);
        formatMenu.add(cancelItem);
        //将格式化菜单添加到编辑菜单中，作为二级菜单
        editMenu.add(new MenuItem("-"));
        editMenu.add(formatMenu);
        //将文件菜单和编辑菜单添加到菜单条中
        menuBar.add(fileMenu);
        menuBar.add(editMenu);
        //把菜单条设置到frame窗口上
        frame.setMenuBar(menuBar);
        //把文本域添加到frame中
        frame.add(ta);
        //设置frame最佳大小并可见
        frame.pack();
        frame.setVisible(true);
    }
    public static void main(String[] args) {
        new SimpleMenu().init();
    }
}

Case 2:

Achieve the following effect through PopupMenu:

Achieved Ideas:

1. Create the PopubMenu menu component;

2. Create multiple MenuItem menu items and add them to the PopupMenu;

3. Add the PopupMenu to the target component Medium;

For components that need to display the PopubMenu menu, register a mouse listener event. When the user releases the right button, the menu pops up.

Demo code 2:

import java.awt.*;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
public class PopupMenuTest {
    private Frame frame = new Frame("这里测试PopupMenu");
    // 创建PopubMenu菜单
    private PopupMenu popupMenu = new PopupMenu();
    // 创建菜单条
    private MenuItem commentItem = new MenuItem("注释");
    private MenuItem cancelItem = new MenuItem("取消注释");
    private MenuItem copyItem = new MenuItem("复制");
    private MenuItem pasteItem = new MenuItem("保存");
    // 创建一个文本域
    private TextArea ta = new TextArea("我爱中华！！！", 6, 40);
    // 创建一个Panel
    private Panel panel = new Panel();
    public void init() {
        // 把菜单项添加到PopupMenu中
        popupMenu.add(commentItem);
        popupMenu.add(cancelItem);
        popupMenu.add(copyItem);
        popupMenu.add(pasteItem);
        // 设置panel大小
        panel.setPreferredSize(new Dimension(300, 100));
        // 把PopupMenu添加到panel中
        panel.add(popupMenu);
        // 为panel注册鼠标事件
        panel.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseReleased(MouseEvent e) {
                boolean flag = e.isPopupTrigger();
                // 判断当前鼠标操作是不是触发PopupMenu的操作
                if (flag) {
                    // 让PopupMenu显示在panel上，并且跟随鼠标事件发生的地方显示
                    popupMenu.show(panel, e.getX(), e.getY());
                }
            }
        });
        // 把ta添加到frame中间区域中
        frame.add(ta);
        // 把panel添加到frame底部
        frame.add(panel, BorderLayout.SOUTH);
        // 设置frame最佳大小，并可视；
        frame.pack();
        frame.setVisible(true);
    }
    public static void main(String[] args) {
        new PopupMenuTest().init();
    }
}

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