尝试将ActionListener添加到JButtons [英] Trying to add ActionListener to JButtons
问题描述
我无法弄清楚如何将 Actionlisteners
添加到 JButton
,任何帮助都将不胜感激。
I cannot figure out how to add Actionlisteners
to the JButton
s, any help would be much appreciated.
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
}
}
推荐答案
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,以帮助更好地解释它们,以及评论中的一些链接以供将来参考。
There are plenty of ways to add an ActionListener
, to a given JComponent
(that supports it's use). I have added some comments in the code snippets, to help explain them a bit better, and some links in the comments for future reference.
1。)如果该类实现 ActionListener
接口,即类本身包含 actionPerformed(...)
方法 ,然后就可以这样做:
1.) If the class implements the ActionListener
interface, i.e. the class itself contains the actionPerformed(...)
method, then one can do it, in this manner:
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。)如果没有想要创建不必要的类
文件。然后可以使用这种方法,使用 EventHandler
:
2.) If one doesn't wants to create unnecessary class
files. Then this approach, which uses, EventHandler
can be used:
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。)如果更关心一个关于 Encapsulation
的概念,这种方法是有益的:
3.) If one is more concern about the concept of Encapsulation
, then this approach is beneficial:
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。)如果更倾向于为了创建匿名类,可以使用以下方法:
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);
}
}
编辑:
5。)此方法包括使用 Action
而不是 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
5.) This approach, includes using Action
instead of ActionListener
. This is to be used for sharing same functionality among various JComponent
s, which leads to code reusability
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);
}
}
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