在Swing中建立彈出選單項

下面的範例展示了如何在Java Swing應用程式中顯示彈出選單。

使用以下API -

• JPopupMenu - 建立彈出選單。
• JMenuItem - 建立選單項。

範例

package com.yiibai.swingdemo;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.JPopupMenu;

public class SwingTester {
    private JFrame mainFrame;
    private JLabel headerLabel;
    private JLabel statusLabel;
    private JPanel controlPanel;

    public SwingTester() {
        prepareGUI();
    }

    public static void main(String[] args) {
        SwingTester swingMenuDemo = new SwingTester();
        swingMenuDemo.showPopupMenuDemo();
    }

    private void prepareGUI() {
        mainFrame = new JFrame("Java SWING建立彈出選單項");
        mainFrame.setSize(400, 400);
        mainFrame.setLayout(new GridLayout(3, 1));

        headerLabel = new JLabel("", JLabel.CENTER);
        statusLabel = new JLabel("", JLabel.CENTER);
        statusLabel.setSize(350, 100);

        mainFrame.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent windowEvent) {
                System.exit(0);
            }
        });
        controlPanel = new JPanel();
        controlPanel.setLayout(new FlowLayout());

        mainFrame.add(headerLabel);
        mainFrame.add(controlPanel);
        mainFrame.add(statusLabel);
        mainFrame.setVisible(true);
    }

    private void showPopupMenuDemo() {
        final JPopupMenu editMenu = new JPopupMenu("Edit");

        JMenuItem cutMenuItem = new JMenuItem("剪下");
        cutMenuItem.setActionCommand("Cut");

        JMenuItem copyMenuItem = new JMenuItem("複製");
        copyMenuItem.setActionCommand("Copy");

        JMenuItem pasteMenuItem = new JMenuItem("貼上");
        pasteMenuItem.setActionCommand("Paste");

        MenuItemListener menuItemListener = new MenuItemListener();

        cutMenuItem.addActionListener(menuItemListener);
        copyMenuItem.addActionListener(menuItemListener);
        pasteMenuItem.addActionListener(menuItemListener);

        editMenu.add(cutMenuItem);
        editMenu.add(copyMenuItem);
        editMenu.add(pasteMenuItem);

        mainFrame.addMouseListener(new MouseAdapter() {
            public void mouseClicked(MouseEvent e) {
                editMenu.show(mainFrame, e.getX(), e.getY());
            }
        });
        mainFrame.add(editMenu);
        mainFrame.setVisible(true);
    }

    class MenuItemListener implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            statusLabel.setText(e.getActionCommand() + " MenuItem clicked.");
        }
    }
}

執行上面範例程式碼，得到以下結果：