java程序得不到想要的结果

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.Frame;
import java.awt.LayoutManager;
import java.awt.Panel;
import java.awt.font.LayoutPath;

import javax.swing.JButton;

public class TextPanel {

/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
Frame f=new Frame("aaa");
f.setLayout(null);
f.setBounds(200, 200, 400, 400);
Panel p1=new Panel();
Panel p2=new Panel();
Panel p3=new Panel();
Panel p4=new Panel();
p1.setBounds(0,0,200,200);
p1.setBackground(Color.black);
p2.setBounds(200,0,200,200);
p2.setBackground(Color.blue);
p3.setBounds(0,200,200,200);
p3.setBackground(Color.green);
p4.setBounds(200,200,200,200);
p4.setBackground(Color.red);
JButton b1=new JButton("黑色");