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Question by ShiftedClock · Sep 12, 2012 at 12:48 AM · nullreferenceexceptiongetcomponent

NullReferenceException when using GetComponent to access script variables

Hi, I've been trying to figure this out for a few days, and I feel utterly defeated coming here to ask. Any help is greatly appreciated.

I'm getting a NullReferenceException on what appears to be straightforward code. I think this stems from a basic misunderstanding of mine about how GetComponent works. Here's the exact error:

NullReferenceException: Object reference not set to an instance of an object

centerCamera..ctor () (at Assets/Scripts/centerCamera.js:5) And here's the code: in centerCamera.js: var target : GameObject; private var grid = target.GetComponent(generateGrid); <-- Line 5 private var gridCenter : Vector3 = grid.gridCenter;
function Update () { transform.LookAt(gridCenter); } and in generateGrid.js: var gridCenter : Vector3 = Vector3(originX, originY, zDepth); // basically Vector3(0, 0, 0.1) Then in the inspector I have a prefab Empty called gameGrid with the script generateGrid attached to it. The script centerCamera is on the mainCamera object in the hierarchy, with "target" being the gameGrid object. Why am I getting this error? Does target.GetComponent(generateGrid) not give me access to the script variables? Shouldn't NullReferenceException not occur if I properly set the target in the inspector? Thanks for your time.
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Answer by DaveA · Sep 12, 2012 at 12:50 AM

private var grid = target.GetComponent(generateGrid); <-- Line 5

You can't do that outside a function. Declare the variable, but set it in Start()

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avatar image ShiftedClock · Sep 14, 2012 at 03:19 PM 0
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Awesome, thanks a bunch. Based on your comment, I was able to figure it out. This also gave me an indicator that I needed to study how Unity's scripting works in a bit more detail. So I've been doing that for a few days, and it's amazing how everything starts to fall into place. Thanks again. :)

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