Basic operation statements of Java forms

package com.swift;
    import java.awt.Color;
    import java.awt.GridLayout;
    import java.util.Random;
    import javax.swing.JFrame;
    import javax.swing.JPanel;
    public class RP_Frame extends JFrame {
    private static final long serialVersionUID = 1L;
    public RP_Frame() {
    setBounds(200, 200, 500, 300);
    //设置窗体大小位置 setTitle("Java窗体的基本操作语句");
    //设置窗体标题 JPanel pnBasic=new JPanel();
    //生成一个大画布 setContentPane(pnBasic);
    //放在窗体中 pnBasic.setLayout(new GridLayout(4,3,5,5));
    //画布按照两行一列网格布局,行与行列与列间隔5像素// JPanel pnGreen=new JPanel();
    //再生成一个小绿画布// JPanel pnYellow=new JPanel();
    //再生成一个小黄画布// pnYellow.setBackground(Color.YELLOW);
    //画布设置颜色// pnGreen.setBackground(Color.GREEN);
    //画布设置颜色// pnBasic.add(pnYellow);
    // pnBasic.add(pnGreen);
    for(int i=0;
    i<(4*3);
    i++) {
    JPanel pn=new JPanel();
    //生成多个小画布 Random ran=new Random();
    int red=ran.nextInt(256);
    int yellow=ran.nextInt(256);
    int blue=ran.nextInt(256);
    pn.setBackground(new Color(red,yellow,blue));
    //画布设置随机颜色 pnBasic.add(pn);
    //放入大画布 }
// final JButton btn = new JButton();
    // btn.setText(" ఠൠఠ小破钮 ఠൠఠ");
    // setContentPane(btn);
    // btn.addActionListener(new ActionListener() {
    // @Override // public void actionPerformed(ActionEvent e) {
    // Random ran = new Random();
    // int index = ran.nextInt(101);
    // System.out.println("Hello!" + index);
    // btn.setText("变变变" + index);
    // }
// }
);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    //设置关闭窗体时程序停止运行 setVisible(true);
    //设置窗体可见，否则什么都不会显示 }
public static void main(String[] args) {
    new RP_Frame();
}
}