Java Nullpointer Exception

import java.util.Random;
import java.util.Scanner;

public class Die {
	
Scanner scan;
Random ran;
int choice;

public static void main(String []arg){
	
Die dice1 = new Die();
Die dice2 = new Die();
dice1.ran = new Random();
dice1.scan = new Scanner(System.in);


	int result = dice1.returnDice()	+ dice2.returnDice();
	System.out.print(result);



} 
    
  
    
    
    
public void Roll(){
	
choice = ran.nextInt(8);

}

public int returnDice(){
return ran.nextInt(8);

}

}