Java NullPointerException

I seem to keep getting the same Exception in my code and I can seem to figure out why ..

public class BattleShip {

public static void main(String[] args) {

System.out.println("Hello World");
Game game = new Game();
Prompter prompter = new Prompter(game);
game.createMap(5);
game.createBattleShips();
prompter.promptForGuess();
game.getxCo();  

}

}

import java.util.ArrayList;

import java.util.Random;

public class Game {

private int mapSize;

private String hits;

private String misses;

ArrayList map = new ArrayList();

public final int NUMBER_OF_SHIPS = 3;

private int[] cooX;

private int[] cooY;

ArrayList guesses = new ArrayList();

private static final int MAX_TRIES = 10;

public void createBattleShipX() {

Random rand = new Random();

int x = 0;

while (x < NUMBER_OF_SHIPS) {

  x++;

  cooX[x] = rand.nextInt(5);

}

}

public void createBattleShipY() {

Random rand = new Random();

int x = 0;

while (x < NUMBER_OF_SHIPS) {

  x++;

  cooY[x] = rand.nextInt(5);

}

}

}

Exception in thread "main" java.lang.NullPointerException
at Game.createBattleShipX(Game.java:94)
at Game.createBattleShips(Game.java:17)
at BattleShip.main(BattleShip.java:8)

I didn't add much of the code due to it not being recognized as 'code'. Thanks for taking the time to read this and help me.