尝试将ActionListener添加到JButtons

Question

我无法弄清楚如何将Actionlisteners添加到JButton，我们将非常感谢您的帮助。

public class Translator extends JPanel implements MouseListener, ActionListener {       

    private JButton french = new JButton();
    private JButton german = new JButton();
    private JButton irish = new JButton();

    public Translator(){
        french = new JButton("French");
        german = new JButton("German");
        irish = new JButton("Irish");           
        setLayout(new GridLayout(2,1));         
        buttonPanel.setLayout(new GridLayout(1,3));
        buttonPanel.add(french);
        buttonPanel.add(german);
        buttonPanel.add(irish);
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        // TODO Auto-generated method stub
    }

    @Override
    public void mouseClicked(MouseEvent e) {
        // TODO Auto-generated method stub
    }

    @Override
    public void mouseEntered(MouseEvent e) {
        // TODO Auto-generated method stub
    }
}

Answer 1

有很多方法可以将ActionListener添加到给定的JComponent（支持它的使用）。我在代码片段中添加了一些注释，以帮助解释它们更好一些，以及评论中的一些链接以供将来参考。

1。）如果类实现了ActionListener接口，即类本身包含actionPerformed(...)方法，那么就可以这样做：

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

public class Skeleton implements ActionListener {   

    private JFrame frame;
    private JPanel contentPane;
    private JButton button;

    private void displayGUI() {
        frame = new JFrame("Skeleton");
        /*
         * EXIT_ON_CLOSE is same as putting System.exit(0),
         * which in some sense, doesnot allows one's
         * application to terminate graciously.
         */ 
        frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);

        contentPane = new JPanel();
        button = new JButton("This is a button.");
        /*
         * This is one way of attaching an ActionListener
         * to the JButton, but the main disadvantage of
         * this approach is, it breaks encapsulation,
         * as you can see the public method, actionPerformed(),
         * is lying free to be accessed by any code outside
         * the scope of the class
         */
        button.addActionListener(this);

        contentPane.add(button);

        frame.setContentPane(contentPane);        
        frame.pack();
        frame.setLocationByPlatform(true);
        frame.setVisible(true);                                
    }

    public static void main(String[] args) {
        Runnable runnable = new Runnable() {
            @Override
            public void run() {
                new Skeleton().displayGUI();
            }
        };
        EventQueue.invokeLater(runnable);
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        JOptionPane.showMessageDialog(frame, "BINGO!",
            "Information: ", JOptionPane.INFORMATION_MESSAGE);
    }    
}

2。）如果不想创建不必要的class文件。然后可以使用EventHandler这种方法：

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

public class Example1 { 

    private JFrame frame;
    private JPanel contentPane;
    private JButton button;

    private void displayGUI() {
        frame = new JFrame("Skeleton");
        /*
         * EXIT_ON_CLOSE is same as putting System.exit(0),
         * which in some sense, doesnot allows one's
         * application to terminate graciously.
         */ 
        frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);

        contentPane = new JPanel();
        button = new JButton("This is a button.");
        /*
         * This is another way of attaching 
         * an ActionListener to the JButton,
         * the main advantage of this approach
         * is, that one does not have to create
         * a new class to handle events
         * More info regarding the use of this 
         * approach, can be found on this link : 
         * http://docs.oracle.com/javase/tutorial/uiswing/events/generalrules.html
         */
        button.addActionListener((ActionListener)
                EventHandler.create(ActionListener.class
                        , Example1.this, "buttonAction", ""));

        contentPane.add(button);

        frame.setContentPane(contentPane);        
        frame.pack();
        frame.setLocationByPlatform(true);
        frame.setVisible(true);                                
    }

    public static void main(String[] args) {
        Runnable runnable = new Runnable() {
            @Override
            public void run() {
                new Example1().displayGUI();
            }
        };
        EventQueue.invokeLater(runnable);
    }

    public void buttonAction(ActionEvent e) {
        JOptionPane.showMessageDialog(frame, "BINGO!",
            "Information: ", JOptionPane.INFORMATION_MESSAGE);
    }    
}

3。）如果有人更关注Encapsulation的概念，那么这种方法是有益的：

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

public class Example2 { 

    private JFrame frame;
    private JPanel contentPane;
    private JButton button;

    private ActionListener buttonActions = 
                            new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent ae) {
            JOptionPane.showMessageDialog(frame, "BINGO!",
                "Information: ", JOptionPane.INFORMATION_MESSAGE);
        }
    };

    private void displayGUI() {
        frame = new JFrame("Skeleton");
        /*
         * EXIT_ON_CLOSE is same as putting System.exit(0),
         * which in some sense, doesnot allows one's
         * application to terminate graciously.
         */ 
        frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);

        contentPane = new JPanel();
        button = new JButton("This is a button.");
        /*
         * This is another way of attaching 
         * an ActionListener to the JButton,
         * the main advantage of this approach
         * is, it adheres to encapsulation.
         */
        button.addActionListener(buttonActions);

        contentPane.add(button);

        frame.setContentPane(contentPane);        
        frame.pack();
        frame.setLocationByPlatform(true);
        frame.setVisible(true);                                
    }

    public static void main(String[] args) {
        Runnable runnable = new Runnable() {
            @Override
            public void run() {
                new Example2().displayGUI();
            }
        };
        EventQueue.invokeLater(runnable);
    }    
}

4。）如果更倾向于创建匿名类，则可以使用此方法：

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

public class Example3 { 

    private JFrame frame;
    private JPanel contentPane;
    private JButton button;

    private void displayGUI() {
        frame = new JFrame("Skeleton");
        /*
         * EXIT_ON_CLOSE is same as putting System.exit(0),
         * which in some sense, doesnot allows one's
         * application to terminate graciously.
         */ 
        frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);

        contentPane = new JPanel();
        button = new JButton("This is a button.");
        /* 
         * This is the fourth way of attaching  
         * an ActionListener to the JButton, 
         * the main advantage of this approach 
         * is, it adheres to encapsulation, the 
         * public method remains hidden
         * inside the Anonymous Class
         * More info can be found on this link : 
         * http://docs.oracle.com/javase/tutorial/java/javaOO/anonymousclasses.html
         * The main disadvantage of this approach is
         * that it doesnot gives you the privilege
         * of separation of concerns, which can
         * be done using the fifth approach,
         * which is MVC - Pattern (Model-View-Controller)
         * and moreover, it creates a hell lot of classes, in 
         * your project, which can lead to extra overhead
         */
        button.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent ae) {
                JOptionPane.showMessageDialog(frame, "BINGO!",
                    "Information: ", JOptionPane.INFORMATION_MESSAGE);
            }
        });

        contentPane.add(button);

        frame.setContentPane(contentPane);        
        frame.pack();
        frame.setLocationByPlatform(true);
        frame.setVisible(true);                                
    }

    public static void main(String[] args) {
        Runnable runnable = new Runnable() {
            @Override
            public void run() {
                new Example3().displayGUI();
            }
        };
        EventQueue.invokeLater(runnable);
    }    
}

修改

5.。此方法包括使用Action代替ActionListener。这将用于在各种JComponent之间共享相同的功能，从而导致代码可重用性

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

public class Example4 { 

    private JFrame frame;
    private JPanel contentPane;
    private JMenuItem showMenuItem;
    private JButton button;

    private Action myActions;

    /*
     * This approach is basically used, when
     * one wants to share the same functionality
     * of different JComponents among each other,
     * without writing redundant codes for each
     * one of those components. Here JMenuItem
     * and JButton are both using the same 
     * functionality, to perform the same task.
     * More info can be found on this link:
     * http://docs.oracle.com/javase/tutorial/uiswing/misc/action.html
     */
    private class MyActions extends AbstractAction {
        public MyActions(String title, String desc) {
            super(title);
            putValue(SHORT_DESCRIPTION, desc);
        }

        @Override
        public void actionPerformed(ActionEvent ae) {
            JOptionPane.showMessageDialog(frame, "BINGO!",
                    "Information: ", JOptionPane.INFORMATION_MESSAGE);
        }
    }

    private void displayGUI() {
        frame = new JFrame("Skeleton");
        /*
         * EXIT_ON_CLOSE is same as putting System.exit(0),
         * which in some sense, doesnot allows one's
         * application to terminate graciously.
         */ 
        frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);

        contentPane = new JPanel();
        button = new JButton("This is a button.");

        myActions = new MyActions("Show", "A small description");
        button.setAction(myActions);

        contentPane.add(button);

        frame.setJMenuBar(getJMenuBar());
        frame.setContentPane(contentPane);        
        frame.pack();
        frame.setLocationByPlatform(true);
        frame.setVisible(true);                                
    }

    private JMenuBar getJMenuBar() {
        JMenuBar menuBar = new JMenuBar();
        JMenu fileMenu = new JMenu("File");
        showMenuItem = new JMenuItem(myActions);
        fileMenu.add(showMenuItem);

        menuBar.add(fileMenu);

        return menuBar;
    }

    public static void main(String[] args) {
        Runnable runnable = new Runnable() {
            @Override
            public void run() {
                new Example4().displayGUI();
            }
        };
        EventQueue.invokeLater(runnable);
    }    
}

Answer 2

french.addActionListener(an_instance_of_the_class_where_actionPerformed_is);

，正如我在编辑后看到的那样，this

此外，请参阅网络角落的this Example和一些教程文字

我认为对教程和许多示例的引用具有高度相关性。

Answer 3

button.addActionListener(<your_ActionListener_here>);

在您的情况下，它将是：

french.addActionListener(this);

如果要对所有三个按钮使用相同的ActionListener，可以使用ActionEvent e的getSource（）函数来检测实际按下的按钮。

Answer 4

如果您使用的是Java8，可以试试这个。

JButton french = new JButton("French");
french.addActionListener(new ActionListener(){
    @Override
    public void actionPerformed(ActionEvent ae){
        System.out.println("Button french clicked!");
    }
});
french.addActionListener(button -> System.out.println("Button Click listener..."));
JFrame frame = new JFrame("Button Listener Test");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(french, BorderLayout.CENTER);
frame.setSize(250, 250);
frame.setVisible(true);

Answer 5

显然，答案是将this放入addActionListener方法。

addActionListener方法将实现 ActionListener接口的对象作为参数，此接口强制您实现/置于代码中{{1当一个动作被触发到被分配的组件时，被调用的方法。

因此，在您的方法中放置actionPerformed，它将在您传递的对象内部搜索this方法的Translator对象并调用它。

actionPerformed

当然，为了工作，有很多代码缺失。

我真的很喜欢@Sandeep使用lambda表达式的答案。 您可以在下面看到完整的示例。

this.french.addActionListener(this);

Answer 6

JButton button = new JButton("Button");
button.addActionListener(new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent e) {
        //To-Do
        //Button clicked
        });

希望这有帮助，它相对简单！您只需要将ActionListener添加到所需的JButton

即可

为了让您更广泛地了解如何在案例场景中实现它，我想在按下按钮后运行新的GUI框架：

startNewFrame.addActionListener(new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent e) {
            System.out.println("Starting new frame");
            SwingUtilities.invokeLater(new Runnable() {
                @Override
                public void run() {
                    NewFrame newFrame = new NewFrame();
                    newFrame.setVisible(true);
                    dispose();//Disposes of current frame
                }
            });
        }
    });