Unity NullReferenceException錯誤

Question

我試圖從魔杖射出光線，並且在運行遊戲時不斷收到此錯誤。燈仍然出來，但錯誤出現在控制檯中。我創建了一個預製燈，並將其拖到我的腳本「Light_Spell」上。下面是代碼：

using UnityEngine; 
using System.Collections; 

public class Light_Spell : MonoBehaviour { 

    //public Light currentSpellLight; 
    private ChangeSpell changespell; 
    private int selectedSpellNum; 
    private bool isSelectedSpell; 

    private Light wandLight; 
    private bool triggerIsPressed; 

    private float life = 1.0f; 
    private float speed = 15.0f; 
    private float timeToDie = 1.0f; 

    [SerializeField] 
    public Light lightProjectile; 

    // Find the light object and disable it 
    void Start() { 

     isSelectedSpell = true; 

     wandLight = GameObject.Find ("Spell_Light").light; 

     wandLight.enabled = false; 
     triggerIsPressed = false; 
    } 

    // Handles button presses etc 
    void Update() { 
     //changespell = currentSpellLight.GetComponent<changespell>(); 

     if(changespell == null) 
      Debug.Log("error"); 
     //Gets the currently selected spell number 
     selectedSpellNum = changespell.GetSelectedSpellNumber(); 

     //Sets whether it is the selected spell 
     if(selectedSpellNum == 3) 
      isSelectedSpell = true; 
     else 
      isSelectedSpell = false; 

     //What happens when trigger is pressed 
     if (isSelectedSpell && SixenseInput.Controllers [0].Trigger != 0) { 
      Debug.Log("Light spell"); 
      triggerIsPressed = true; 
      wandLight.enabled = true; 
      wandLight.intensity = (float)(SixenseInput.Controllers [0].Trigger) * 3; 
      wandLight.range = (float)(SixenseInput.Controllers[0].Trigger) * 5; 
     } 
     else { 
      triggerIsPressed = false; 
      wandLight.enabled = false; 
     } 

    //What happens when bumper is pressed 
     if (isSelectedSpell && SixenseInput.Controllers [0].GetButtonDown (SixenseButtons.BUMPER) && triggerIsPressed == false) { 
      Debug.Log("Light spell"); 
      var instantiateProjectile = Instantiate(lightProjectile, transform.position, transform.rotation) as Light; 

      //instantiateProjectile.transform.TransformDirection(new Vector3(5,5,5)); 
     } 
} 

//When bumper button is pressed, the light flashes briefly 
private void LightBurst(){ 
    wandLight.intensity = 1; 

} 

private void LightBurstActivated(){ 
    timeToDie = Time.time + life; 
    transform.position = Camera.main.transform.position; 
    transform.rotation = Camera.main.transform.rotation; 
} 

private void DeactivateLightBurst(){ 
    this.gameObject.SetActive(false); 
} 

private void LightBurstCountdown(){ 
    if(timeToDie < Time.time) 
     DeactivateLightBurst(); 
} 

private void MoveLight(){ 
    Vector3 velocity = speed * Time.deltaTime * transform.forward; 
    transform.Translate(velocity * 3); 
} 

}

我得到的錯誤是：

NullReferenceException: Object reference not set to an instance of an object 
Light_Spell.Update() (at Assets/Scripts/Spells/Light_Spell.cs:39) 

感謝所有幫助

Answer 1

我覺得這是不是你所得到的第一個錯誤。 遊戲對象「WandLightSpell」沒有燈光，或者沒有找到具有該名稱的任何遊戲對象，並且在Start()處獲得空引用例外。