编者注

一直理解错了Unity的对象注入，以为是在Compontent指定脚本所绑定的对象，就能够成功，但是发现这个是错误的理解。

Unity错误 - NullReferenceException

错误代码

using System.Collections;using System.Collections.Generic;using UnityEngine;using UnityEngine.UI;public class SliderLightBehaviourScript : MonoBehaviour {	public GameObject light;	// Use this for initialization	void Start () {		//this.light = GameObject.Find ("Directional Light");	}		// Update is called once per frame	void Update () {			}	public void OnDrag(float value){		Debug.LogError (value);		this.light.transform.rotation = Quaternion.Euler (new Vector3(value,0.y,0));	}}

报错

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

问题理解

GameObject的场景内创建的对象没有绑定到代码对象上。确定通过Component无法绑定GameObject。

通过查询发现

获取GameObject对象必须通过GameObject.Find或者相关函数进行实现，无法通过其他方式。

解决代码

using System.Collections;using System.Collections.Generic;using UnityEngine;using UnityEngine.UI;public class SliderLightBehaviourScript : MonoBehaviour {	public GameObject light;	// Use this for initialization	void Start () {		this.light = GameObject.Find ("Directional Light");	}		// Update is called once per frame	void Update () {			}	public void OnDrag(float value){		Vector3 light_rotation = light.transform.rotation.eulerAngles;		Debug.LogError (value);		this.light.transform.rotation = Quaternion.Euler (new Vector3(value,light_rotation.y,0));	}}