creating a button using Swing

creating a button

import java.awt.color.*;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class SimpleFrame
{
public static void main(String args[])
{
 MyFrame F=new MyFrame();
}
}
class MyFrame extends JFrame implements ActionListener
{
    JPanel p=new JPanel();
    JButton a=new JButton("YELLOW");
    JButton b=new JButton("BLUE");
    JButton c=new JButton("RED");
    JButton d=new JButton("GREEN");
MyFrame()
{
    p.add(a);
    p.add(b);
    p.add(c);
    p.add(d);
    a.addActionListener(this);
    b.addActionListener(this);
    c.addActionListener(this);
    d.addActionListener(this);
    add(p);
    setVisible(true);
}
public void actionPerformed(ActionEvent e)
{
    if(e.getSource()==a)
    {
        p.setBackground(Color.yellow);
    }
    if(e.getSource()==b)
    {
        p.setBackground(Color.blue);
    }
      if(e.getSource()==c)
      {
           p.setBackground(Color.red);
    }
    if(e.getSource()==d)
    {
     p.setBackground(Color.green);
}
}
}

output:

if u click the yellow button below colour will be display.