Cant fix a null reference exception?

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1

So I’m getting a null reference exception and I can’t figure out how to fix it. Heres the code and line its on.

private var ship : GameObject;
private var planets : Array;
private var stuckDistance : float;
private var planet : GameObject;

function Start () {
ship = GameObject.Find("Ship");
planets = new Array();
planets.length = 4;
planets[0] = GameObject.Find("Planet_1");
planets[1] = GameObject.Find("Planet_2");
planets[2] = GameObject.Find("Planet_3");
planets[3] = GameObject.Find("Planet_4");
stuckDistance = 15.0f;
}

function Update () {
    for (var p = 0; p < 4; p++)
    {    	
        if((Vector3.Distance (transform.position, planets[p].transform.position)) <= stuckDistance)
    	{
    	    planet = planets[p]; 
    	}
    }
    transform.position = planet.transform.position;//line with null exception
    refueling = true;
}

my working theory right now is maybe i have to declare the array differently? I'm looking at the scripting reference but I'm not seeing anything very helpful. anyone have any ideas?

1 Answer

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2

If you had used ‘#pragma strict’ at the top of the file, your code would generate an error which I believe points you in the right direction. First avoid the ‘Array’ class. If you need an array and you know it size (i.e. it does not have to grow), use a built-in array. If it needs to grow or change size, consider a .NET generic List. Here is a reference:

http://wiki.unity3d.com/index.php?title=Which_Kind_Of_Array_Or_Collection_Should_I_Use%3F

As for your specific bug here, delete lines 8 and 9 and declare your array on line 2 as:

private var planets : GameObject[] = new GameObject[4];

Note you if you still get a null reference exception, then it is likely that your GameObject.Find() is failing. Check for exact spelling and case.