帮我看看这个事件处理的程序！它有个错误帮我改一下

Question

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class ButtonTest
{
public static void main(String args[])
{
ButtonFrame frame=new ButtonFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}class ButtonFrame extends JFrame
{
public ButtonFrame()
{
setTitle("ButtonTest");
setSize(300,200);
ButtonPanel panel=new ButtonPanel();
add(panel);
}
}
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);
}
} class ColorAction implements ActionListener
{
public ColorAction(Color c)
{
backgroundColor=c;
}
public void actionPerformed(ActionEvent event)
{
setBackground(backgroundColor);
}
     private Color backgroundColor;
}

Answer 1

import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;public class ButtonTest
{
public static void main(String[] args)
{
ButtonFrame frame = new ButtonFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}class ButtonFrame extends JFrame
{
public ButtonFrame()
{
setTitle("ButtonTest");
setSize(300, 200);
ButtonPanel panel = new ButtonPanel();
add(panel);
}
}class ButtonPanel extends JPanel implements ActionListener
{
public ButtonPanel()
{
JButton yellowButton = new JButton("yellow");
JButton blueButton = new JButton("Blue");
JButton redButton = new JButton("red");
add(yellowButton);
add(blueButton);
add(redButton);
yellowButton.addActionListener(this);
yellowButton.setActionCommand("yellow");
blueButton.addActionListener(this);
blueButton.setActionCommand("blue");
redButton.addActionListener(this);
redButton.setActionCommand("red");
} public void actionPerformed(ActionEvent e)
{
if(e.getActionCommand().equals("yellow"))
setBackground(Color.yellow);
else if(e.getActionCommand().equals("blue"))
setBackground(Color.blue);
else if(e.getActionCommand().equals("red"))
setBackground(Color.red);
}
}

Answer 2

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class ButtonTest
{
public static void main(String args[])
{
ButtonFrame frame=new ButtonFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}class ButtonFrame extends JFrame
{
public ButtonFrame()
{
setTitle("ButtonTest");
setSize(300,200);
ButtonPanel panel=new ButtonPanel();
add(panel);
}
}
class ButtonPanel extends JPanel implements ActionListener
{
public ButtonPanel()
{
JButton yellowButton=new JButton("yellow");
JButton blueButton=new JButton("Blue");
JButton redButton=new JButton("red");
add(yellowButton);
add(blueButton);
add(redButton);
yellowButton.addActionListener(this);
blueButton.addActionListener(this);
redButton.addActionListener(this);
}
public void actionPerformed(ActionEvent event){
//System.out.println("111");
if(event.getActionCommand()=="yellow") {
System.out.println("0000");
setBackground(Color.yellow);
}
if(event.getActionCommand()=="Blue") {
setBackground(Color.blue);
}
if(event.getActionCommand()=="red") {
setBackground(Color.red);
}
}
}