NullReferenceException on a copy of working code

Unity Engine
1

So I’ve got this piece of code which manages (or is supposed to I guess) 4 arrays of game objects. The problem is really on all lines of the SpawnAsteroid method but the if statement. All of them throw the same error when separated. I have no idea what could be causing this, especially since I have another method in this very same script that has nothing but the same code as the problematic function (in a slightly different manner) and works without problems:

The problematic code:

public class AsteroidInstatiator : MonoBehaviour {
    public int LargestAsteroidArraySize = 2;
    public GameObject Asteroid1;
    public GameObject Asteroid2;
    public GameObject Asteroid3;
    public GameObject Asteroid4;
    public Vector2 ArrayPosition;
    public Rigidbody2D Player;

    private Rigidbody2D[] Asteroid1Array;
    private Rigidbody2D[] Asteroid2Array;
    private Rigidbody2D[] Asteroid3Array;
    private Rigidbody2D[] Asteroid4Array;
    private int[] iteratorArray;

    void Start()
    {
        iteratorArray = new int[4];

        Asteroid1Array = new Rigidbody2D[LargestAsteroidArraySize];
        Asteroid2Array = new Rigidbody2D[LargestAsteroidArraySize * 2];
        Asteroid3Array = new Rigidbody2D[LargestAsteroidArraySize * 4];
        Asteroid4Array = new Rigidbody2D[LargestAsteroidArraySize * 8];

        for (int i = 0; i < LargestAsteroidArraySize; i++)
        {
            Asteroid1Array[i] = GameObject.Instantiate(Asteroid1, ArrayPosition, Quaternion.identity).GetComponent<Rigidbody2D>();
            Asteroid1Array[i].gameObject.SetActive(false);
        }

        for (int i = 0; i < LargestAsteroidArraySize * 2; i++)
        {
            Asteroid2Array[i] = GameObject.Instantiate(Asteroid2, ArrayPosition, Quaternion.identity).GetComponent<Rigidbody2D>();
            Asteroid2Array[i].gameObject.SetActive(false);
        }

        for (int i = 0; i < LargestAsteroidArraySize * 4; i++)
        {
            Asteroid3Array[i] = GameObject.Instantiate(Asteroid3, ArrayPosition, Quaternion.identity).GetComponent<Rigidbody2D>();
            Asteroid3Array[i].gameObject.SetActive(false);
        }

        for (int i = 0; i < LargestAsteroidArraySize * 8; i++)
        {
            Asteroid4Array[i] = GameObject.Instantiate(Asteroid4, ArrayPosition, Quaternion.identity).GetComponent<Rigidbody2D>();
            Asteroid4Array[i].gameObject.SetActive(false);
        }
    }

    public void SpawnAsteroid(int asteroidIndex)
    {
        if (asteroidIndex == 1)
        {
            Asteroid1Array[iteratorArray[0]].gameObject.SetActive(true);
            Asteroid1Array[iteratorArray[0]].position = Vector2.zero;
            if (iteratorArray[0] >= LargestAsteroidArraySize * 2) iteratorArray[0] = 0;
            else iteratorArray[0]++;
        }
    }
}

The working code (lower in the same script, thus with the same Start function):

    public void OnAsteroidDestroyal(GameObject CurrentAsteroidPrefab, Rigidbody2D CurrentRB)
    {
        if (CurrentAsteroidPrefab.name == "Asteroid_1(Clone)")
        {
            Asteroid2Array[iteratorArray[1]].gameObject.SetActive(true);
            Asteroid2Array[iteratorArray[1]].position = CurrentRB.GetComponent<Rigidbody2D>().position + new Vector2(-5f, -5f);
            Asteroid2Array[iteratorArray[1]].velocity = CurrentRB.GetComponent<Rigidbody2D>().velocity;
            if (iteratorArray[1] >= LargestAsteroidArraySize * 2) iteratorArray[1] = 0;
            else iteratorArray[1]++;

            Asteroid2Array[iteratorArray[1]].gameObject.SetActive(true);
            Asteroid2Array[iteratorArray[1]].position = CurrentRB.GetComponent<Rigidbody2D>().position + new Vector2(5f, 5f);
            Asteroid2Array[iteratorArray[1]].velocity = CurrentRB.GetComponent<Rigidbody2D>().velocity;
            if (iteratorArray[1] >= LargestAsteroidArraySize * 2) iteratorArray[1] = 0;
            else iteratorArray[1]++;
        }
//repeated four times for four arrays, not bothering you with that

I’ve tried making the arrays public but that doesn’t seem to help. What am I doing wrong?

2

What line is the error on?

1 Like
3

Asteroid1Array[iteratorArray[0]].gameObject.SetActive(true);

and it moves to

Asteroid1Array[iteratorArray[0]].position = Vector2.zero;

when I comment it

EDIT: it also moves to

if (iteratorArray[0] >= LargestAsteroidArraySize * 2) iteratorArray[0] = 0;
else iteratorArray[0]++;

so I guess the problem is with the int array

EDIT2: The error appears on the first two lines even when I hardcode a number in instead of referrencing the array, so I guess the problem has to do with both

4

Where do you populate your iteratorArray? I see you initialize it, but you don’t assign any values to it.

1 Like
5

Well shouldn’t all the values be defaulted to 0? The 2nd example, which works with the array as well, works as it is supposed to

6

You are correct. Moment of stupid on my part. The only other option is your Asteroid1Array has null values in it. When you make it public, is it fully populated?

1 Like
7

Yep, 5 elements, each is a rigidbody of a unique object in the scene.
Also, for some reason, the Asteroid1Array[iteratorArray[0]].position = Vector2.zero; line throws a OutOfRange exeption when I make the IteratorArray public. This doesn’t seem to happen with the second example.

8

So okay the problem seems to be me calling the function out of a different script for some reason. It works well when I call it out of the same script

9

I would show the other script. Sounds like you’re calling another instance of the script where the arrays are not initialized.

Or you’re trying to access the script in Awake/Start from another script before the values are assigned in this script, which would give you the error.

1 Like
10

Oh god right, I’m accessing the function out of a Start of another script, that has to be the problem. I can’t try it out right now, but it’s the most reasonable answer I can think of. Thanks a lot