Thread: Null Pointer Exception-Freecell

Hello, I am looking for some help for a class I have, I am currently getting a null pointer exception on line 10 of my Freecell.java class

Here's my code:

Freecell.java:

import java.awt.*;
import javax.swing.*;
import java.util.*;
public class Freecell extends JApplet{
	Deck a = new Deck();
	public static ArrayList [] piles = new ArrayList[8];
	public void init() {
		a = Deck.shuffle(a);
		for(int i = 0; i<8; i++){
			piles[i].add(new ArrayList());
			Pile.makePile(a, i);
		}
		repaint();
	}
	public void paint (Graphics g){
 
	}
}

Card.java:

import java.awt.*;
import javax.swing.*;
import java.util.*;
public class Card {
	public int suite;
	public int rank;
	public Card(){
		suite= 0;
		rank=0;
	}
	public Card(int rnk, int sui){
		rank = rnk;
		suite = sui;
	}
	public static String cardString(Card crd){
		int rnk = crd.rank;
		int sui = crd.suite;
		String output = new String();
		if(rnk == 2){
			output = "Two";
		}else if(rnk == 3){
			output = "Three";
		}else if(rnk == 4){
			output = "Four";
		}else if(rnk == 5){
			output = "Five";
		}else if(rnk == 6){
			output = "Six";
		}else if(rnk == 7){
			output = "Seven";
		}else if(rnk == 8){
			output = "Eight";
		}else if(rnk == 9){
			output = "Nine";
		}else if(rnk == 10){
			output = "Ten";
		}else if(rnk == 11){
			output = "Jack";
		}else if(rnk == 12){
			output = "Queen";
		}else if(rnk == 13){
			output = "King";
		}else if(rnk == 14){
			output = "Ace";
		}else if(rnk == 0){
			output = "Zero";
		}else {
			output = "" + rnk;
		}
		output += " of ";
		if(sui == 1){
			output += "Diamonds";
		}else if(sui == 2){
			output += "Hearts";
		}else if(sui == 3){
			output += "Clubs";
		}else if(sui == 4){
			output += "Spades";
		}else if(sui == 0){
			output += "Nothing";
		}else{
			output += sui;
		}
		return output;
	}
	public static String cardFileString(Card crd){
		int rnk = crd.rank;
		int sui = crd.suite;
		String output = new String();
		if(rnk == 2){
			output = "2";
		}else if(rnk == 3){
			output = "3";
		}else if(rnk == 4){
			output = "4";
		}else if(rnk == 5){
			output = "5";
		}else if(rnk == 6){
			output = "6";
		}else if(rnk == 7){
			output = "7";
		}else if(rnk == 8){
			output = "8";
		}else if(rnk == 9){
			output = "9";
		}else if(rnk == 10){
			output = "t";
		}else if(rnk == 11){
			output = "j";
		}else if(rnk == 12){
			output = "q";
		}else if(rnk == 13){
			output = "k";
		}else if(rnk == 14){
			output = "a";
		}else if(rnk == 0){
			output = "0";
		}else {
			output = "e";
		}
		if(sui == 1){
			output += "d";
		}else if(sui == 2){
			output += "h";
		}else if(sui == 3){
			output += "c";
		}else if(sui == 4){
			output += "s";
		}else if(sui == 0){
			output += "0";
		}else{
			output += "e";
		}
		output += ".gif";
		return output;
	}
	public static Card getCard(int numb){
		Card crd = new Card((((numb-1)%13)+2),(((numb -1)/13)+1));
		return crd;
	}
}

Deck.java:

import java.awt.*;
import javax.swing.*;
import java.util.*;
public class Deck {
	public Card [] deck = new Card [52];
	Deck(){
		for(int i = 1; i < 53; i++){
			Card crd = new Card();
			crd = Card.getCard(i);
			deck[i - 1] = crd;
		}
	}
	public static Deck shuffle (Deck dk){
		Deck tmp = dk;
		for(int i = 0; i < 100; i++){
			Random r = new Random();
			int rnd1 = r.nextInt(51)+1;
			int rnd2 = r.nextInt(51)+1;
			Card temp = tmp.deck[rnd1];
			tmp.deck[rnd1] = tmp.deck[rnd2];
			tmp.deck[rnd2] = temp;
		}
		return tmp;
	}
}

Pile.java:

import java.awt.*;
import javax.swing.*;
import java.util.*;
public class Pile {
	public static ArrayList <Card> pile = new ArrayList();
	public Pile() {
		pile = pile;
	}
	public static void makePile (Deck dk, int num){
		if(num < 1 || num > 8){
			return;
		}else{
			for(int i = 44; i%8+num > -1; i--){
				Freecell.piles[num].add(dk.deck[i]);
			}
		}
	}
}

Any help would be appreciated,

Thanks