Issues when running Applet

[Richard Greere]

Hi,

I'm trying to create an applet that simulates a race between a tortoise and a hare. The code seems to make sense to me, however I get a series of errors when attempting to run the program. I know its a lot of code, but any help is appreciated and the errors received are posted beneath the code.
(I know this isn't the most efficient way to do this, but I'm fairly new to Java)

import java.awt.*;
import java.awt.image.BufferedImage;
import java.applet.*;
import java.net.URL;
import java.util.*;

public class project2 extends Applet {
	
	Random gen=new Random();
	private int harePos;
	private int turtPos;
	Image turt;
	Image hare;
	URL url;
	Timer timer=new Timer();
	private static int end = 2500;
	Graphics g;
 
    public void init(){
    	url=getDocumentBase();
        turt = getImage(url,"tortoise.gif");
        hare = getImage(url,"hare.gif");
        
    }
  
 
    public void paint (Graphics g){
    	makeGrid(g);
    	
    	g.drawImage(turt, 0, 0, 50, 50, this);
    	g.drawImage(hare, 0, 50, 50, 50, this);
    	while (turtPos < end && harePos < end){
    		turtle();
    		hare();
    		
    		
    	}
    	if (harePos==end)
    		g.drawString("The Hare Wins!", 100, 110);
    	else if (turtPos==end)
    		g.drawString("The Tortoise Wins!", 100, 110);


    	
    }
    
    public void makeGrid(Graphics g){
        int x=50;
        for(int i=0;i<50;i++){
          g.drawLine(x, 0, x, 100);
             x=x+50;
        }
        g.drawLine(0, 50, 2500, 50);
        }
    
    public void turtle(){
    	int action=gen.nextInt(10)+1;
    	int [] fast={1,2,3,4,5};
    	int [] slow={6,7,8};
    	int [] slip={9,10};
    	
    	for (int i=0;i<fast.length;i++)
    		if (action==fast[i])
    			turtFast();
    	for (int i=0;i<slow.length;i++)
    		if (action==slow[i])
    			turtSlow();
    	for (int i=0;i<slip.length;i++)
    		if (action==slip[i])
    			turtSlip();
    	
    }
    
    public void turtFast(){
    	g.clearRect(turtPos,0,50,50);
    	if ((end-turtPos)<150)
    		turtPos=end;
    	else
    	turtPos=turtPos+150;
    	
    	g.drawImage(turt, turtPos, 0, 50, 50, this);
    }

    public void turtSlow(){
    	g.clearRect(turtPos, 0, 50,50);
    	if ((end-turtPos)<50)
    		turtPos=end;
    	else
    	turtPos=turtPos+50;
    	
    	g.drawImage(turt, turtPos, 0, 50,50,this);
    }
    
    public void turtSlip(){
    	g.clearRect(turtPos,0,50,50);
    	if (turtPos<300)
    		turtPos=0;
    	else
    		turtPos=turtPos-300;
    	
    	g.drawImage(turt, turtPos, 0,50,50,this);
    	
    	
    }
    
    
    /////////////////////////////////////////////////////////////////////////////////////////////////
    
    public void hare(){
    	int action=gen.nextInt(10)+1;
    	int [] big={1,2};
    	int [] small={3,4,5};
    	int [] bigSlip={6};
    	int [] smallSlip={7,8};
    	int [] sleep={9,10};
    	
    	for (int i=0;i<big.length;i++)
    		if (action==big[i])
    			hareBig();
    	for (int i=0;i<small.length;i++)
    		if (action==small[i])
    			hareSmall();
    	for (int i=0;i<bigSlip.length;i++)
    		if (action==bigSlip[i])
    			hareBigSlip();
    	for (int i=0;i<smallSlip.length;i++)
    		if (action==smallSlip[i])
    			hareSmallSlip();
    	for (int i=0;i<sleep.length;i++)
    		if (action==sleep[i])
    			hareSleep();
    }
    
    public void hareBig(){
    	g.clearRect(harePos,50,50,50);
    	if ((end-harePos)<450)
    		harePos=end;
    	else
    	harePos=harePos+450;
    	
    	g.drawImage(hare, harePos, 50, 50, 50, this);
    }
	public void hareSmall(){
		g.clearRect(harePos,50,50,50);
		if ((end-harePos)<50)
    		harePos=end;
    	else
    	harePos=harePos+50;
		
    	g.drawImage(hare, harePos, 50, 50, 50, this);
	}
	public void hareBigSlip(){
		g.clearRect(harePos, 50,50,50);
		if (harePos<600)
			harePos=0;
		else
			harePos=harePos-600;
		
		g.drawImage(hare, harePos, 50,50,50,this);
	}
	public void hareSmallSlip(){
		g.clearRect(harePos, 50,50,50);
		if (harePos<100)
			harePos=0;
		else
			harePos=harePos-100;
		
		g.drawImage(hare, harePos, 50,50,50,this);
	}
	public void hareSleep(){
		
	}
  
 }

I receive the following errors when I compile and run this:

Exception in thread "AWT-EventQueue-1" java.lang.NullPointerException
	at project2.turtSlip(project2.java:98)
	at project2.turtle(project2.java:73)
	at project2.paint(project2.java:34)
	at sun.awt.RepaintArea.paintComponent(Unknown Source)
	at sun.awt.RepaintArea.paint(Unknown Source)
	at sun.awt.windows.WComponentPeer.handleEvent(Unknown Source)
	at java.awt.Component.dispatchEventImpl(Unknown Source)
	at java.awt.Container.dispatchEventImpl(Unknown Source)
	at java.awt.Component.dispatchEvent(Unknown Source)
	at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
	at java.awt.EventQueue.access$000(Unknown Source)
	at java.awt.EventQueue$1.run(Unknown Source)
	at java.awt.EventQueue$1.run(Unknown Source)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
	at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
	at java.awt.EventQueue$2.run(Unknown Source)
	at java.awt.EventQueue$2.run(Unknown Source)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
	at java.awt.EventQueue.dispatchEvent(Unknown Source)
	at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
	at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
	at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
	at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
	at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
	at java.awt.EventDispatchThread.run(Unknown Source)

Again, any help is appreciated and thanks in advance.