Java 如何使 JMenu 项在单击时执行某些操作

How to make a JMenu item do something when it's clicked

提问by PulsePanda

I'm making a GUI that has a Jmenu; it has the jmenu items that will be doing things when clicked. That is the problem. I've looked and looked, but I can't find out how to make it do something when clicked. Also, I am kind of a noob, so if you could make it do it in a pretty simple way, that would be great!

我正在制作一个带有 Jmenu 的 GUI；它有 jmenu 项，单击时将执行操作。那就是问题所在。我看了又看，但我不知道如何让它在点击时做一些事情。另外，我是个菜鸟，所以如果你能以一种非常简单的方式做到这一点，那就太好了！

Here's the code:

这是代码：

import java.awt.Color;
import java.awt.Component;
import javax.swing.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import javax.swing.*;

public abstract class windowMaker extends JFrame implements ActionListener {
private JMenu menuFile;

public static void main(String[] args) {
    createWindow();

}

public static void createWindow() {
    JFrame frame = new JFrame();
    frame.setTitle("*Game Title* Beta 0.0.1");
    frame.setSize(600, 400);
    frame.setLocation(100, 100);
    frame.setVisible(true);
    frame.setResizable(false);
    frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
    frame.setJMenuBar(windowMaker.menuBarCreator());
    frame.add(windowMaker.setTitle());
}

public static void launchURL(String s) {
    String s1 = System.getProperty("os.name");
    try {

        if (s1.startsWith("Windows")) {
            Runtime.getRuntime()
                    .exec((new StringBuilder())
                            .append("rundll32   url.dll,FileProtocolHandler ")
                            .append(s).toString());
        } else {
            String as[] = { "firefox", "opera", "konqueror",   "epiphany",
                    "mozilla", "netscape" };
            String s2 = null;
            for (int i = 0; i < as.length && s2 == null; i++)
                if (Runtime.getRuntime()
                        .exec(new String[] { "which", as[i]   }).waitFor() == 0)
                    s2 = as[i];

            if (s2 == null)
                throw new Exception("Could not find web browser");
            Runtime.getRuntime().exec(new String[] { s2, s });
        }
    } catch (Exception exception) {
        System.out
                .println("An error occured while trying to open the            web browser!\n");
    }
}

public static  JMenuBar menuBarCreator() {
    // create the menu parts
    JMenuBar menuBar = new JMenuBar();
    JMenu menuFile = new JMenu("File");
    JMenu menuHelp = new JMenu("Help");
    JMenuItem menuFileWebsite = new JMenuItem("Website");
    JMenuItem menuFileExit = new JMenuItem("Exit");
    JMenuItem menuHelpRules = new JMenuItem("Rules");
    JMenuItem menuHelpAbout = new JMenuItem("About");
    JMenuItem menuHelpHow = new JMenuItem("How To Play");

    // make the shortcuts for the items
    menuFile.setMnemonic(KeyEvent.VK_F);
    menuHelp.setMnemonic(KeyEvent.VK_H);

    // put the menu parts with eachother
    menuBar.add(menuFile);
    menuBar.add(menuHelp);
    menuFile.add(menuFileWebsite);
    menuFile.add(menuFileExit);
    menuHelp.add(menuHelpRules);
    menuHelp.add(menuHelpAbout);
    menuHelp.add(menuHelpHow);


    return menuBar;
}

public static Component setTitle() {
    JLabel title = new JLabel("Welcome To *the game*");
    title.setVerticalAlignment(JLabel.TOP);
    title.setHorizontalAlignment(JLabel.CENTER);
    return title;
}

}

BTW: I want the website option (let's just work with that for now) to use the launchURL method; I know that one works.

顺便说一句：我希望网站选项（让我们现在就使用它）使用 launchURL 方法；我知道一个有效。

采纳答案by Steve Kuo

A JMenuItemis a form of a button (AbstractButton). The normal pattern is to construct your button with an Action(see JMenuItem's constructor). The Actiondefines the name and action to be performed. Most people extend AbstractActionand implement actionPerformedwhich is invoked when the button is pressed.

AJMenuItem是按钮 ( AbstractButton) 的一种形式。正常模式是用 构造按钮Action（请参阅JMenuItem的构造函数）。该Action定义的名称和要执行的操作。大多数人扩展AbstractAction并实现actionPerformed按下按钮时调用的功能。

A possible implementation might look like:

一个可能的实现可能如下所示：

JMenuItem menuItem = new JMenuItem(new AbstractAction("My Menu Item") {
    public void actionPerformed(ActionEvent e) {
        // Button pressed logic goes here
    }
});

or:

或者：

JMenuItem menuItem = new JMenuItem(new MyAction());
...
public class MyAction extends AbstractAction {
    public MyAction() {
        super("My Menu Item");
    }

    public void actionPerformed(ActionEvent e) {
        // Button pressed logic goes here
    }
}

Note that everything I said above also applies to JButton. Also take a look at Java's very helpful How to Use Actionstutorial.

请注意，我上面所说的一切也适用于JButton. 还可以查看 Java 非常有用的How to Use Actions教程。

回答by Costis Aivalis

Although it is better to use Actions, you can also add an ActionListener to your JMenuItem1 like this:

虽然使用 Actions 更好，但您也可以像这样向 JMenuItem1 添加 ActionListener：

jMenuItem1.addActionListener(new java.awt.event.ActionListener() {
    public void actionPerformed(java.awt.event.ActionEvent evt) {
        jMenuItem1ActionPerformed(evt);
    }
});

and then implement the action in jMenuItem1ActionPerformed(evt):

然后在 jMenuItem1ActionPerformed(evt) 中实现动作：

private void jMenuItem1ActionPerformed(java.awt.event.ActionEvent evt) {
    // TODO add your handling code here:
    javax.swing.JOptionPane.showMessageDialog(null, "foo");
    // more code...
}

For your code:

对于您的代码：

    ...
    JMenuItem menuFileWebsite = new JMenuItem("Website");
    JMenuItem menuFileExit = new JMenuItem("Exit");
    menuFileExit.addActionListener(new java.awt.event.ActionListener() {
        @Override
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            menuFileExitActionPerformed(evt);
        }
    });
    JMenuItem menuHelpRules = new JMenuItem("Rules");

and:

和：

private static void menuFileExitActionPerformed(java.awt.event.ActionEvent evt) {
    System.exit(0);
}

回答by Wajdy Essam

For adding any actions into button, just make object from class that implement ActionListener interface:

要将任何操作添加到按钮中，只需从实现 ActionListener 接口的类中创建对象：

menuFileWebsite.addActionListener(new ActionListener() {
    public void actionPerformed(ActionEvent e) {
        launchURL("http://www.google.com");
    }
});

here we make anonymous inner object that implement Actionlistener interface, and override actionperforemed method to do its work

这里我们创建了实现 Actionlistener 接口的匿名内部对象，并覆盖 actionperforemed 方法来完成它的工作

i make some changes in your code, to follow java standard on naming class, and create any GUI components in EDT.

我对您的代码进行了一些更改，以遵循命名类的 Java 标准，并在 EDT 中创建任何 GUI 组件。

// WindowMakerDemo.java

import java.awt.Component;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;

import javax.swing.*;


public final class WindowMakerDemo  {
    public static void main(String[] args) {
       EventQueue.invokeLater(new Runnable() {
           @Override
           public void run() {
                JFrame frame = new MyFrame();
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setTitle("*Game Title* Beta 0.0.1");
                frame.setSize(600, 400);
                frame.setLocation(100, 100);
                frame.setResizable(false);
                frame.setVisible(true);
           }
       });
    }
}

 final class MyFrame extends JFrame{

    public MyFrame() {
       createWindow();
    }

    private void createWindow() {
        setJMenuBar(menuBarCreator());
        add(setTitle());
    }

    private JMenuBar menuBarCreator() {
        // create the menu parts
        JMenuBar menuBar = new JMenuBar();
        JMenu menuFile = new JMenu("File");
        JMenu menuHelp = new JMenu("Help");

        JMenuItem menuFileWebsite = new JMenuItem("Website");
        JMenuItem menuFileExit = new JMenuItem("Exit");
        JMenuItem menuHelpRules = new JMenuItem("Rules");
        JMenuItem menuHelpAbout = new JMenuItem("About");
        JMenuItem menuHelpHow = new JMenuItem("How To Play");

        // website button action
        menuFileWebsite.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                launchURL("http://www.google.com");
            }
        });

        // exit action
        menuFileExit.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                System.exit(0); 
            }
        });

        // make the shortcuts for the items
        menuFile.setMnemonic(KeyEvent.VK_F);
        menuHelp.setMnemonic(KeyEvent.VK_H);

        // put the menu parts with eachother
        menuBar.add(menuFile);
        menuBar.add(menuHelp);

        menuFile.add(menuFileWebsite);
        menuFile.add(menuFileExit);

        menuHelp.add(menuHelpRules);
        menuHelp.add(menuHelpAbout);
        menuHelp.add(menuHelpHow);

        return menuBar;
    }

    private Component setTitle() {
        JLabel title = new JLabel("Welcome To *the game*");
        title.setVerticalAlignment(JLabel.TOP);
        title.setHorizontalAlignment(JLabel.CENTER);
        return title;
    }

    private void launchURL(String s) {
        String s1 = System.getProperty("os.name");
        try {

            if (s1.startsWith("Windows")) {
                Runtime.getRuntime().exec((new StringBuilder()).append("rundll32 url.dll,FileProtocolHandler ").append(s).toString());
            } else {
                String as[] = {"firefox", "opera", "konqueror", "epiphany",
                    "mozilla", "netscape"};
                String s2 = null;
                for (int i = 0; i < as.length && s2 == null; i++) {
                    if (Runtime.getRuntime().exec(new String[]{"which", as[i]}).waitFor() == 0) {
                        s2 = as[i];
                    }
                }

                if (s2 == null) {
                    throw new Exception("Could not find web browser");
                }
                Runtime.getRuntime().exec(new String[]{s2, s});
            }
        } catch (Exception exception) {
            System.out.println("An error occured while trying to open the            web browser!\n");
        }
    }
}