problem

Coin

package twelve;
import java.awt.Image;
import java.awt.Graphics;

public class Coin {
	private Image heads;
	private Image tails; 
	private char side;
	
	
	
	public Coin(Image h, Image t){
		this.heads = h;
		this.tails = t;
		side = 'h';
	}
	
	public void flip(){
		if (side == 'h'){
			side = 'j';
		}
		else side = 'h';
		
	}
	
	public void draw(Graphics g, int x, int y){
		if (side == 'h'){
			g.drawImage(heads, x, y, null);

		}
		else g.drawImage(tails, tails.getHeight(null), tails.getWidth(null), null);
		
	}
	
	
}

CoinTest

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

public class CoinTest extends JPanel
   implements ActionListener
{
  private Coin coin;

  public CoinTest ()
  {
    Image heads = (new ImageIcon("heads.gif")).getImage();
    Image tails = (new ImageIcon("tails.gif")).getImage();
    coin = new Coin(heads, tails);

    Timer clock = new Timer(2000, this);
    clock.start();
  }

  public void paintComponent(Graphics g)
  {
    super.paintComponent(g);

    int x = getWidth() / 2;
    int y = getHeight() / 2;
    coin.draw(g, x, y);
  }

  public void actionPerformed(ActionEvent e)
  {
    coin.flip();
    repaint();
  }

  public static void main(String[] args)
  {
    JFrame w = new JFrame("Flipping coin");
    w.setSize(300, 300);
    w.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    CoinTest panel = new CoinTest();
    panel.setBackground(Color.WHITE);
    Container c = w.getContentPane();
    c.add(panel);

    w.setVisible(true);
  }
}