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

/** This class is used to demo the use of a JPanel. An
    An instance has labels in the north and south and
    a JPanel with four buttons in the center.
  */
public class PanelDemo extends JFrame {

 JPanel p= new JPanel();
 
 /** Constructor: an invisible frame with title t, two labels in the 
     north and south and a JPanel of 4 buttons in the center */
 public PanelDemo(String t) {
  super(t);
  
  p.add(new JButton("0"));
  p.add(new JButton("1"));
  p.add(new JButton("2"));
  p.add(new JButton("3"));
  
  Container cp= getContentPane();
  cp.add(new JLabel("north"),BorderLayout.NORTH);
  cp.add(new JLabel("south"),BorderLayout.EAST);
  cp.add(p,BorderLayout.CENTER);
   
  pack();
 }
 
 public static void main(String[] args) {
  PanelDemo pd= new PanelDemo("demo JPanel");
  pd.setVisible(true);
 }

}