16.3

import java.awt.BorderLayout;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ComponentEvent;
import java.awt.event.ComponentListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class Test_16 extends JFrame implements ActionListener{
    private JButton j1 = new JButton("left");
    private JButton j2 = new JButton("right");
    private JButton j3 = new JButton("up");
    private JButton j4 = new JButton("down");
    private JP j = new JP();
    private int x =100,y =200;
    
    public Test_16(){
        JPanel J = new JPanel();
        J.add(j1);J.add(j2);J.add(j3);J.add(j4);
        j1.addActionListener(this);
        j2.addActionListener(this);
        j3.addActionListener(this);
        j4.addActionListener(this);
        add(J,BorderLayout.SOUTH);
        add(j,BorderLayout.CENTER);
    }    
    
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Test_16 t1 = new Test_16();
        t1.setTitle("Test_16");
        t1.setSize(400,400);
        t1.setFocusable(true);
        t1.setLocationRelativeTo(null);
        t1.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        t1.setVisible(true);        
    }    
    
    class JP extends JPanel{
        private int radius = 5;
        
        protected void paintComponent(Graphics g){
            super.paintComponent(g);
            g.drawOval(x, y, 2*radius, 2*radius);
        }        
    }
    public void actionPerformed(ActionEvent e) {
        // TODO Auto-generated method stub
        if(e.getSource() == j1)
        {        
            x -= 20;
            repaint();
        }
        else if(e.getSource() == j2){
            x += 20;
            repaint();
        }else if(e.getSource() == j3){
            y -= 20;
            repaint();
        }else if(e.getSource() == j4){
            y += 20;
            repaint();
        }            
    }    
}