Failing to reference an instantiated object

Question

I am trying to instantiate an enemy object with some input parameters for the enemy's health and damage like this:

 if (Input.GetKeyDown(KeyCode.T))
         {
             GameObject enemy = Instantiate(whatToSpawn, this.transform.position, this.transform.rotation) as GameObject;
             enemy.GetComponent<Enemy>().changeStats(health, damage);
         }

it does spawn the enemy object, but it fails to create a reference to it, and I get "NullReferenceException: Object reference not set to an instance of an object" error in Unity. What am I doing wrong? I have looked at several threads where this is how people pass parameters to instantiated objects.

I have made sure that the newly instantiated object prefab does in fact have an Enemy component and that it contains the changeStats() method.

Answer 1

Best Answer

Answer by ninja_gear · May 30, 2016 at 02:51 PM

make sure whatToSpawn is a GameObject, or your code will choke when attempting to cast with as and null will be returned

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eguels · May 30, 2016 at 02:55 PM 0

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This solved the problem! Thanks a bunch!

That's strange, though. I always see people expose their game object variables as Transforms.

Thanks again!

ninja_gear eguels · May 30, 2016 at 06:09 PM 1

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Always save what you are going to use:

   if (Input.Get$$anonymous$$eyDown($$anonymous$$eyCode.T))
   {
     Enemy enemy = Instantiate(whatToSpawn as GameObject, this.transform.position, this.transform.rotation).GetComponent<Enemy>() ;
     enemy.changeStats(health, damage);
   }

Answer 2

Answer by Arsineh · May 30, 2016 at 02:45 PM

did you initialize your public variable in Inspector? probably when you create an object in script and it is public, you will see the variable in inspector and you need to give it a parameter to initialize.

Hope this can solve the problem

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eguels · May 30, 2016 at 02:58 PM 0

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Yeah, the problem was that I stored the prefab as a Transform, and not as a GameObject. I'm still not sure why, though, Transform usually gets the job done, and I thought it would be castable as a GameObject anyway. It wasn't.

Thank you for giving it a shot!

Answer 3

Answer by vittu1994 · May 30, 2016 at 01:58 PM

Try:

 GameObject enemy = (GameObject)Instantiate(whatToSpawn, this.transform.position, this.transform.rotation);

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eguels · May 30, 2016 at 02:14 PM 0

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Now it says

 Cannot cast from source type to destination type.

vittu1994 eguels · May 30, 2016 at 02:38 PM 0

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Is the Enemy script attached to the enemy object you are trying to instantiate?

eguels vittu1994 · May 30, 2016 at 02:50 PM 0

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Yes, it is. It was even available as an auto-complete suggestion, along with the other scripts the prefab has.

Failing to reference an instantiated object

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