package com.yjq.lesson06; //import java.awt.Color; //import java.awt.event.ActionEvent; //import java.awt.event.ActionListener; //import java.awt.event.WindowAdapter; //import java.awt.event.WindowEvent; import javax.swing.; import java.awt.; import java.awt.event.*; public class Test_4 extends JFrame { //三个按钮 JButton jb1,jb2,jb3; //三原色初始值 int r=100,g=100,b=255; JPanel jp=new JPanel(); Test_4() { jp.setBackground(new Color(r,g,b)); jp.setLayout(null); this.setSize(320, 240); this.add(jp); this.addWindowListener(new WindowAdapter() { public void windowClosed(WindowEvent e) { System.exit(0); } }); //对三个按钮的设置 jb1=new JButton("红色"); jb2=new JButton("绿色"); jb3=new JButton("蓝色"); jb1.setBackground(Color.RED); jb2.setBackground(Color.GREEN); jb3.setBackground(Color.BLUE); jb1.setBounds(20,80,80,40); jb2.setBounds(120,80,80,40); jb3.setBounds(220,80,80,40); jb1.addActionListener(new changeColor()); jb2.addActionListener(new changeColor()); jb3.addActionListener(new changeColor()); jp.add(jb1); jp.add(jb2); jp.add(jb3); this.setVisible(true); } private class changeColor implements ActionListener { public void actionPerformed(ActionEvent e) { if(e.getSource()==jb1) { r+=10; if(r>255)r=0; jp.setBackground(new Color(r,g,b)); } if(e.getSource()==jb2) { g+=10; if(g>255) g=0; jp.setBackground(new Color(r,g,b)); } if(e.getSource()==jb3) { b+=10; if(b>255) b=0; jp.setBackground(new Color(r,g,b)); } } } public static void main(String[] args) { new Test_4(); } } 帮我注释一下代码

package com.yjq.lesson06;

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

public class Test_4 extends JFrame {

    // 三个按钮
    JButton jb1, jb2, jb3;

    // 三原色初始值
    int r = 100, g = 100, b = 255;

    JPanel jp = new JPanel();

    Test_4() {
        jp.setBackground(new Color(r, g, b));
        jp.setLayout(null);
        this.setSize(320, 240);
        this.add(jp);

        // 窗口关闭事件
        this.addWindowListener(new WindowAdapter() {
            public void windowClosed(WindowEvent e) {
                System.exit(0);
            }
        });

        // 对三个按钮的设置
        jb1 = new JButton("红色");
        jb2 = new JButton("绿色");
        jb3 = new JButton("蓝色");

        jb1.setBackground(Color.RED);
        jb2.setBackground(Color.GREEN);
        jb3.setBackground(Color.BLUE);

        jb1.setBounds(20, 80, 80, 40);
        jb2.setBounds(120, 80, 80, 40);
        jb3.setBounds(220, 80, 80, 40);

        jb1.addActionListener(new changeColor());
        jb2.addActionListener(new changeColor());
        jb3.addActionListener(new changeColor());

        jp.add(jb1);
        jp.add(jb2);
        jp.add(jb3);

        this.setVisible(true);
    }

    private class changeColor implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            if (e.getSource() == jb1) {
                r += 10;
                if (r > 255)
                    r = 0;
                jp.setBackground(new Color(r, g, b));
            }
            if (e.getSource() == jb2) {
                g += 10;
                if (g > 255)
                    g = 0;
                jp.setBackground(new Color(r, g, b));
            }
            if (e.getSource() == jb3) {
                b += 10;
                if (b > 255)
                    b = 0;
                jp.setBackground(new Color(r, g, b));
            }
        }
    }

    public static void main(String[] args) {
        new Test_4();
    }

}

注释：

1.导入需要的类

2.定义一个类Test_4，继承JFrame

3.定义三个按钮jb1,jb2,jb3

4.定义三原色初始值r,g,b

5.定义一个面板jp

6.在构造函数中初始化窗口、面板、按钮

7.添加窗口关闭事件

8.为三个按钮设置背景色、位置和监听器

9.定义一个内部类changeColor，实现ActionListener接口

10.在内部类中实现对三个按钮的监听事件

11.定义main方法，创建Test_4对象，运行程序