Java摇摆 |弹出菜单

JPopupMenu 是 javax.swing 包中的一个类。它是 PopupMenu 的一个实现。 JPopupMenu 生成一个小窗口，弹出并显示一系列选项。 JPopupMenu 可用于在容器内的任何位置生成一个小窗口。
该类的构造函数是：

1. JPopupMenu() : 创建一个空名称的弹出菜单
   
2. JPopupMenu(String name) : 创建一个带有指定标题的弹出菜单。
   

JPopupMenu 常用的方法有：

1. add(JMenuItem menuItem) ：将 menuItem 添加到弹出菜单。
   
2. add(String s) ：将字符串添加到弹出菜单中。
   
3. String getLabel() : 获取弹出菜单的标签。
   
4. boolean is Visible() : 返回 JPopup 菜单是否可见。
   
5. setLabel(String s) ：设置弹出菜单的标签。
   
6. setLocation(int x, int y) ：将弹出菜单的位置设置为给定坐标
   
7. setPopupSize(int width, int height) ：设置弹出窗口的大小以给出高度和宽度
   
8. setVisible(boolean b) ：设置弹出菜单的可见性，如果 true 作为参数传递，则可见，反之亦然。
   
9. show(Component c, int x, int y) : 在组件 c 内的 x, y 位置显示弹出菜单。
   

1.程序显示一个简单的弹出菜单

Java

// Java program to show a simple popup menu
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
class Popup extends JFrame implements ActionListener {
 
    // java button
    static JButton b;
 
    // java frame
    static JFrame f;
 
    // popup menu
    static JPopupMenu pm;
 
    // default constructor
    Popup()
    {
    }
 
    // main class
    public static void main(String[] args)
    {
        // create a frame
        f = new JFrame("Popup");
 
        // set the size of the frame
        f.setSize(400, 400);
 
        // close the frame when close button is pressed
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 
        // create anew panel
        JPanel p = new JPanel();
 
        // create an object of mouse class
        Popup pop = new Popup();
 
        // create a button
        b = new JButton("click");
 
        // addActionListener
        b.addActionListener(pop);
        p.add(b);
        f.add(p);
        f.show();
    }
 
    // when the button is clicked
    public void actionPerformed(ActionEvent e)
    {
        String s = e.getActionCommand();
        if (s.equals("click")) {
            // create a popup menu
            pm = new JPopupMenu("Message");
 
            // create a label
            JLabel l = new JLabel("this is the popup menu");
 
            // add the label to the popup
            pm.add(l);
 
            // add the popup to the frame
            pm.show(f, 100, 100);
        }
    }
}

输出 ：

2.程序显示弹出菜单和菜单项

Java

// Java program to show a popup menu
// and menu items to it
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
class Popup extends JFrame implements ActionListener {
 
    // java button
    static JButton b;
 
    // java frame
    static JFrame f;
 
    // popup menu
    static JPopupMenu pm;
 
    // JLabel
    JLabel l;
 
    // default constructor
    Popup()
    {
    }
 
    // main class
    public static void main(String[] args)
    {
        // create a frame
        f = new JFrame("Popup");
 
        // set the size of the frame
        f.setSize(400, 400);
 
        // close the frame when close button is pressed
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 
        // create anew panel
        JPanel p = new JPanel();
 
        // create an object of mouse class
        Popup pop = new Popup();
 
        // create a button
        b = new JButton("click");
 
        // addActionListener
        b.addActionListener(pop);
 
        // create a popup menu
        pm = new JPopupMenu("Message");
 
        // create menuItems
        JMenuItem m1 = new JMenuItem("Item1");
        JMenuItem m2 = new JMenuItem("Item2");
        JMenuItem m3 = new JMenuItem("Item3");
 
        // create a Jlabel
        JLabel l = new JLabel("nothing clicked");
 
        // add menuitems to popup menu
        pm.add(m1);
        pm.add(m2);
        pm.add(m3);
 
        // addActionListener
        m1.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e)
            {
                l.setText("Item 1 clicked.");
            }
        });
 
        m2.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e)
            {
                l.setText("Item 2 clicked.");
            }
        });
 
        m3.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e)
            {
                l.setText("Item 3 clicked.");
            }
        });
 
        // add button and label to frame
        p.add(b);
        p.add(l);
 
        f.add(p);
        f.show();
    }
 
    // when the button is clicked
    public void actionPerformed(ActionEvent e)
    {
        String s = e.getActionCommand();
        if (s.equals("click")) {
 
            // add the popup to the frame
            pm.show(f, 200, 200);
        }
    }
}

输出 ：

注意：此代码可能无法在在线 IDE 中运行，请使用离线编译器