NullReferanceException When Enemy touches Player

Question

Hello - Will here, After creating a short script (supplied bellow) I have noticed an error occurring: When the enemy touches the player, rather than taking the 10 health away, an error message is broadcasted; "NullReferanceException: Object Referance not set to an instance of an object." I am assuming this is what is stopping the health from being taken away. Many Thanks, Will.

var health = 100;

var healthcount : Transform;

var enemy : Transform;

function Update () {

     healthcount.transform.GetComponent.<TextMesh>().text = health.ToString();

}

function OnTriggerEnter (other : Collider) {

     if (other.Collider.enemy){
     health -= 10;
     }

}

Answer 1

Best Answer

Answer by Daemonhahn · Jul 25, 2017 at 03:55 PM

Because you are getting the component in Update, it is likely not available yet.

Instead cache this reference in Start so you dont get it each time.

Like this:

      Text healthText;
 
 void Start()
 {
 healthText = healthcount.transform.GetComponent.<TextMesh>();
 }
 
 void Update()
 {
 healthText.text = health.ToString();
 }

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BadwolfX · Jul 25, 2017 at 04:02 PM 0

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I attempted a change: var health = 100; var healthcount : Transform; var enemy : Transform; var healthText; function Start() { healthText = healthcount.transform.GetComponent.(); }

function Update() { healthText.text = health.ToString(); }

function OnTriggerEnter (other : Collider) { if (other.Collider.enemy){ health -= 10; } }

However I still get the error, you used void, I tried my best to translate to JavaScript.

Daemonhahn BadwolfX · Jul 25, 2017 at 04:13 PM 1

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But you are trying to get (other.Collider.enemy) and yet you do not do a get component to get the enemy? How are you getting the .enemy, as it looks to me like it would give a null reference as there is no reference for it.

Also try learning c#, you will find it more robust and a lot more tutorials use c# than javascript.

Daemonhahn Daemonhahn · Jul 25, 2017 at 04:15 PM 0

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something like

 Enemy enemy = other.Collider.GetComponent<Enemy>();
 if(enemy)
 {
  // rest of code 
 }

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Answer 2

Answer by wizbit · Jul 25, 2017 at 03:52 PM

Hey BadwolfX

i believe it may be that you have not set the within your healthcount.transform.GetComponent.().text = health.ToString().

https://docs.unity3d.com/ScriptReference/GameObject.GetComponent.html

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BadwolfX · Jul 25, 2017 at 04:02 PM 0

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The page is unfortunately all C#?

Daemonhahn BadwolfX · Jul 25, 2017 at 04:17 PM 0

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I recommend learning C# as javascript is not widely used for Unity anymore and has many caveats

NullReferanceException When Enemy touches Player

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