NullReferenceExeption on OnCharacterControllerHit

Question

In my game, when a character jumps on a certain object, it is supposed to do something. As the code follows, when the character jumps on a object, the character takes the parent's name. Depending on the name, it will do something, but at the if.. then.. statement in the code, there is a NullReferenceExeption when the character jumps on anything. Heres the code:

 function OnControllerColliderHit (hit : ControllerColliderHit) {
     var name = hit.gameObject.transform.parent.name;
     if (name == "Thing") {
         Debug.Log("Yay!");
     }
 }

Answer 1

Best Answer

Answer by robertbu · Feb 17, 2013 at 07:42 PM

Your code will will generate a null reference exception if the game object you collided with does not have a parent. If parent == null then your "parent.name" will generate the exception.

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zardini123 · Feb 17, 2013 at 11:31 PM 0

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I tried your idea with this code:

 function OnControllerColliderHit (hit : ControllerColliderHit) {
     var name : String;
     
     if (hit.collider.transform.childCount == 0) {
         name = hit.gameObject.transform.name;
     } else if (hit.collider.transform.childCount > 0) {  
         name = hit.gameObject.transform.parent.name;
     } 
     
     if (name == "Thing") {
         Debug.Log("Yay!");
     }
 }

Still, a NullReferenceException.

Starkid225 · Feb 17, 2013 at 11:42 PM 0

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The NullReferenceException should provide you will a line number. Could you post the full output of the error in the Error log?

zardini123 · Feb 18, 2013 at 12:12 AM 0

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Sure. It says: NullReferenceException CharacterDini.OnControllerColliderHit (UnityEngine.ControllerColliderHit hit) (at Assets/Zardainian Quest/Assets/Characters/Main Characters/Dini/CharacterDini.js:217) UnityEngine.CharacterController:Move(Vector3) CharacterDini:FixedUpdate() (at Assets/Zardainian Quest/Assets/Characters/Main Characters/Dini/CharacterDini.js:194)

Just letting you guys know, the line #'s don't coordinate with the code i have posted before, so yeah.

robertbu · Feb 18, 2013 at 01:12 AM 0

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I've never used childCount, but according to the reference, transform.childCount is the number of children of a specific transform. It does not indicate that the transform has a parent. I'd change your check to

 if (hit.collider.transform.parent == null)

zardini123 · Feb 18, 2013 at 02:05 PM 0

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That worked perfectly! Thank you!

NullReferenceExeption on OnCharacterControllerHit

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