大家帮我改下这个程序看？麻烦了！！！

Question

if (ce==yellowButton) this.setBackground(Color.yellow);
        else if (e==blueButton) this.setBackground(Color.blue);
        else if (e==redButton) this.setBackground(Color.red);
是“==“不是“=“，还有几个问题，我还没有改好

Answer 1

修订程序如下》：
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;class ButtonPanel extends JPanel
{
public ButtonPanel()
{
JButton yellowButton=new JButton("yellow");
JButton blueButton=new JButton("blue");
JButton redButton=new JButton("red");


add(yellowButton);
add(blueButton);
add(redButton);

ColorAction yellowAction=new ColorAction(Color.yellow);
ColorAction blueAction=new ColorAction(Color.blue);
ColorAction redAction=new ColorAction(Color.red);

yellowButton.addActionListener(yellowAction);
blueButton.addActionListener(blueAction);
redButton.addActionListener(redAction);
}

private class ColorAction implements ActionListener{
public ColorAction(Color c)
{
backgroundColor=c;
}
public void actionPerformed(ActionEvent event)
{
setBackground(backgroundColor);
repaint();
}

private Color backgroundColor;
}
}class ButtonFrame extends JFrame
{
public ButtonFrame()
{
setTitle("ButtonTest");
setSize(WIDTH,HEIGHT);

ButtonPanel panel=new ButtonPanel();
Container contentPanel=getContentPane();
contentPanel.add(panel);
}
public static final int WIDTH=300;
public static final int HEIGHT=500;
}public class ButtonTest
{
public static void main(String[] args)
{
ButtonFrame frame=new ButtonFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.show();
}
}

Answer 2

程序我自己已经该好了，如下：
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.EventObject;
public class ButtonTest2
{
    public static void main(String[] args)
    {
        ButtonFrame frame=new ButtonFrame();
        frame.setDefaultCloseOperation(frame.EXIT_ON_CLOSE);
        frame.show();
    }
}
class ButtonFrame2 extends JFrame
{
    public ButtonFrame2()
    {
        setTitle("ButtonTest");
        this.setSize(WIDTH,HEIGHT);
        ButtonPanel2 panel=new ButtonPanel2();
        Container contentpanel=this.getContentPane();
        contentpanel.add(panel);
    }
    public final int WIDTH=300;
    public final int HEIGHT=200;
}class ButtonPanel2 extends JPanel implements ActionListener
{
    JButton yellowButton,blueButton,redbutton;
    Object source;
    public ButtonPanel2()
    {
        //create button
        JButton yellowButton=new JButton("yellow");
        JButton blueButton=new JButton("blue");
        JButton redButton=new JButton("red");
        //add button
        this.add(yellowButton);
        this.add(blueButton);
        this.add(redButton);
        yellowButton.addActionListener(this);
        blueButton.addActionListener(this);
        redButton.addActionListener(this);
    }
    public void actionPerformed(ActionEvent e)
    {
        EventObject event=new EventObject(source);
        Object ce=event.getSource();
        if (ce==yellowButton) this.setBackground(Color.yellow);
        else if (e==blueButton) this.setBackground(Color.blue);
        else if (e==redButton) this.setBackground(Color.red);
    }}但是我还是有个问题，我记得比较基本类型的字段是用＝＝，但比较对象字段是用
equals(object)阿。但这里用了＝＝竟然也可以，不知道为什么？

Answer 3

equals比较的只是对象的参数！！！

Answer 4

topology:equals() compares the reference of the two objects

Answer 5

JButton yellowButton,blueButton,redbutton;
    Object source;
    public ButtonPanel2()
    {
        //create button
        JButton yellowButton=new JButton("yellow");
        JButton blueButton=new JButton("blue");
        JButton redButton=new JButton("red");这种写法是错误的,全局变量中的按钮是空值.

Answer 6

class ButtonPanel2 extends JPanel implements ActionListener
{
    JButton yellowButton,blueButton,redbutton;
    Object source;
    public ButtonPanel2()
    {
        //create button
        JButton yellowButton=new JButton("yellow");
        JButton blueButton=new JButton("blue");
        JButton redButton=new JButton("red");
        //add button
        this.add(yellowButton);
        this.add(blueButton);
        this.add(redButton);
        yellowButton.addActionListener(this);
        blueButton.addActionListener(this);
        redButton.addActionListener(this);
    }
    public void actionPerformed(ActionEvent e)
    {
        EventObject event=new EventObject(source);
                                         <<=====source在那里得到值？
        ... ...
    }

Answer 7

假如我不声明：
JButton yellowButton,blueButton,redbutton;
编译就不能通过阿，何况这里虽然是空值，但在构造方法中已经新建了对象了阿。这里只是声明一下。至于<<=====source在那里得到值，确实这是个问题，我是想用EventObject的getSource方法，但这个方法的参数是（Object source），所以我就那样写了，程序也没有报错。具体请高手详细说明一下吧！！！期待.........

Answer 8

我发现程序这样写也可以运行：
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.EventObject;
public class ButtonTest2
{
    public static void main(String[] args)
    {
        ButtonFrame frame=new ButtonFrame();
        frame.setDefaultCloseOperation(frame.EXIT_ON_CLOSE);
        frame.show();
    }
}
class ButtonFrame2 extends JFrame
{
    public ButtonFrame2()
    {
        setTitle("ButtonTest");
        this.setSize(WIDTH,HEIGHT);
        ButtonPanel2 panel=new ButtonPanel2();
        Container contentpanel=this.getContentPane();
        contentpanel.add(panel);
    }
    public final int WIDTH=300;
    public final int HEIGHT=200;
}class ButtonPanel2 extends JPanel implements ActionListener
{
    //JButton yellowButton,blueButton,redButton;
    Object yellowButton,blueButton,redButton,source;
    public ButtonPanel2()
    {
        //create button
        JButton yellowButton=new JButton("yellow");
        JButton blueButton=new JButton("blue");
        JButton redButton=new JButton("red");
        //add button
        this.add(yellowButton);
        this.add(blueButton);
        this.add(redButton);
        yellowButton.addActionListener(this);
        blueButton.addActionListener(this);
        redButton.addActionListener(this);
    }
    public void actionPerformed(ActionEvent e)
    {
        EventObject event=new EventObject(source);//or new EventObject(null)
        Object ce=event.getSource();
        if (ce.equals(yellowButton)) this.setBackground(Color.yellow);
        else if (ce.equals(blueButton)) this.setBackground(Color.blue);
        else if (ce.equals(redButton)) this.setBackground(Color.red);
    }}

Answer 9

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.EventObject;public class ButtonTest {
    
    public static void main(String[] args) {
        
        ButtonFrame frame=new ButtonFrame();
        frame.addWindowListener(new WindowAdapter(){
            public void windowClosing(WindowEvent e)
                {System.exit(0);}
            });
        frame.show();
    }
}
class ButtonFrame extends JFrame {
    
    public final int WIDTH=300;
    public final int HEIGHT=200;
    
    public ButtonFrame() {
        setTitle("ButtonTest");
        this.setSize(WIDTH,HEIGHT);
        ButtonPanel panel=new ButtonPanel();
        Container contentpanel=this.getContentPane();
        contentpanel.add(panel);
    }
    
}
class ButtonPanel extends JPanel implements ActionListener {
    
    public JButton yellowButton, blueButton, redButton;
    
    public ButtonPanel() {
        
        //create button
        yellowButton = new JButton("yellow");
        blueButton = new JButton("blue");
        redButton = new JButton("red");
        
        //add button
        this.add(yellowButton);
        this.add(blueButton);
        this.add(redButton);
        
        yellowButton.addActionListener(this);
        blueButton.addActionListener(this);
        redButton.addActionListener(this);
    }
    
    public void actionPerformed(ActionEvent e) {
        
        if (e.getSource() == yellowButton) this.setBackground(Color.yellow);
        else if (e.getSource() == blueButton) this.setBackground(Color.blue);
        else if (e.getSource() == redButton) this.setBackground(Color.red);
    }}

Answer 10

frame.setDefaultCloseOperation(frame.EXIT_ON_CLOSE);这句怎么报错？？Container contentpanel=this.getContentPane(); 是什么意思，哪位给解释一下。

Answer 11

for HawaiiLeo(红桃K)
你那个肯定不行的，ActionEvent没有getsource()的方法，所以e.getSource() == yellowButton肯定编译通不过。我用的是java.swing.*,所以必须把组件放在内容面板上，所以有：
Container contentpanel=this.getContentPane();