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Question by DayMoniakk · Jul 28, 2017 at 11:18 AM · c#error messagedetectionhealth

NullReferenceException by detecting health

Hello everyone, I'm working on a fps zombie game, currently I'm writing the code for the AI of the zombies.

My AI use a detection for don't attacking a player already dead, for detect this I use this line of code :

         if (CurrentHealth > 0 && PlayerHealth.CurrentHealth > 0) 
         {
             anim.SetBool ("IsIdle", false);
             nav.SetDestination (player.position);
             nav.speed = ZombieSpeed;
         }

"CurrentHealth" is the current health of my zombie and "PlayerHealth.CurrentHealth" is the current health of the player.

So i want to detect if my zombie and my player have more than 0 health point to trigger the attack. Unity give me this error : "NullReferenceException: Object reference not set to an instance of an object" The problem seems to coming from the "if(......)", but I don't know what I'm doing wrong, all works perfectly except this.

So this piece of code is not correct ? Where is my mistake(s) ? I looked at different websites/forum, but I've don't found a solution.

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avatar image vir1234 · Jul 28, 2017 at 11:20 AM 0
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post full code

avatar image DayMoniakk vir1234 · Jul 28, 2017 at 11:22 AM 0
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 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class ZombieAI : $$anonymous$$onoBehaviour 
 {
     public float ZombieSpeed = 3f;
     public float TimeBetwheenAttacks = 0.5f;
     public int AttackDamage = 10;
     public int StartingHealth = 50;
     public int CurrentHealth;
 
     private Transform player;
     private Animator anim;
     private UnityEngine.AI.Nav$$anonymous$$eshAgent nav;
     private PlayerHealth playerHealth;
     private bool PlayerInRange;
     private bool IsDead;
 
     void Awake ()
     {
         player = GameObject.FindGameObjectWithTag ("Player").transform;
         nav = GetComponent<UnityEngine.AI.Nav$$anonymous$$eshAgent> ();
         playerHealth = player.GetComponent<PlayerHealth> ();
         CurrentHealth = StartingHealth;
         PlayerInRange = false;
         IsDead = false;
     }
 
     void Update ()
     {
         if (CurrentHealth > 0 && PlayerHealth.CurrentHealth > 0) 
         {
             anim.SetBool ("IsIdle", false);
             nav.SetDestination (player.position);
             nav.speed = ZombieSpeed;
         }
     }
 
 }

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Answer by vir1234 · Jul 28, 2017 at 11:29 AM

first you havent set reference anim in the script. is your CurrentHealth is static?

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avatar image DayMoniakk · Jul 28, 2017 at 11:32 AM 0
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I didn't see, I fixed this but I have still the same problem

avatar image vir1234 DayMoniakk · Jul 28, 2017 at 11:34 AM 0
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use if (CurrentHealth > 0 && playerHealth.CurrentHealth > 0) and are you sure is there Player tag on the object ?

avatar image DayMoniakk vir1234 · Jul 28, 2017 at 11:36 AM 0
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$$anonymous$$y bad, I launched again the game and the error just disappear. I feel stupid ... I can't believe it's don't work because of the animator !

Thanks you for your help, now I can keep working on my game

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