Unity3D: NullReferenceException: Object reference not set to an instance of an object

Question

I want to access Hero.class variable "aspect" from laserController.class, but I receive an error message : NullReferenceException: Object reference not set to an instance of an object.

Hero.class

using UnityEngine;
using System.Collections;

public class Hero : MonoBehaviour {

public float aspect = 0.1f;
void Update () {

    }
}

laserController.class

using UnityEngine;
using System.Collections;

public class laserController : MonoBehaviour {

public float health = 0f;
//public float aspect = 0.1f;

void OnCollisionEnter(Collision collision) {
    if(collision.gameObject.tag == "enemy"){
        Destroy(gameObject);
        Destroy(collision.gameObject);
    }
 }      

void Update () {

    Hero direction = gameObject.GetComponent<Hero>();

    //LaserHealth
    health += Time.deltaTime;

    if(health > 7f){
        Destroy(gameObject);
    } 
    //problem in here
    transform.Translate(Vector3.up * -direction.aspect);

    }
}

possible duplicate of What is a NullReferenceException and how do I fix it? — CodeSmile
– CodeSmile, Commented Feb 16, 2015 at 10:45

Heisenbug · Accepted Answer · 2013-07-11 09:20:46Z

2

I guess your Hero component isn't attached to the same GameObject where laserController is attached to. If you want to force that condition you can use a RequireComponentAttribute:

[RequireComponent(typeof(Hero))]
public class laserController : MonoBehaviour

Some other unrelated consideration:

Defining a empty Update method is useless and has performances overhead
Try to follow consistence naming conventions for classes (camel case: laserController -> LaserController)

answered Jul 11, 2013 at 9:20

Heisenbug

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