Why does this Instantiate give a Null Reference Exception?

Question

Hey Comm-unity, I am working on a project, and I can't seem to get it to stop returning a null reference exception. Here's the code:

 Slide s = new Slide();
             GameObject g = GameObject.Instantiate(ButtonPrefab, new Vector3(slides[slides.Count - 1].button.transform.position.x + xpos, slides[slides.Count - 1].button.transform.position.y + ypos, 0.0f), Quaternion.identity) as GameObject;
             s.button = g.GetComponent<Button>();
             s.button.transform.SetParent(ButtonParent.transform);
             slides.Add (s);

And here's the error:

 NullReferenceException: Object reference not set to an instance of an object
 Manager.Add () (at Assets/Scripts/Manager.cs:110)
 UnityEngine.Events.InvokableCall.Invoke (System.Object[] args) (at C:/buildslave/unity/build/Runtime/Export/UnityEvent.cs:137)
 UnityEngine.Events.InvokableCallList.Invoke (System.Object[] parameters) (at C:/buildslave/unity/build/Runtime/Export/UnityEvent.cs:601)
 UnityEngine.Events.UnityEventBase.Invoke (System.Object[] parameters) (at C:/buildslave/unity/build/Runtime/Export/UnityEvent.cs:743)
 UnityEngine.Events.UnityEvent.Invoke () (at C:/buildslave/unity/build/Runtime/Export/UnityEvent_0.cs:53)
 UnityEngine.UI.Button.Press () (at C:/buildslave/unity/build/Extensions/guisystem/UnityEngine.UI/UI/Core/Button.cs:35)
 UnityEngine.UI.Button.OnPointerClick (UnityEngine.EventSystems.PointerEventData eventData) (at C:/buildslave/unity/build/Extensions/guisystem/UnityEngine.UI/UI/Core/Button.cs:44)
 UnityEngine.EventSystems.ExecuteEvents.Execute (IPointerClickHandler handler, UnityEngine.EventSystems.BaseEventData eventData) (at C:/buildslave/unity/build/Extensions/guisystem/UnityEngine.UI/EventSystem/ExecuteEvents.cs:52)
 UnityEngine.EventSystems.ExecuteEvents.Execute[IPointerClickHandler] (UnityEngine.GameObject target, UnityEngine.EventSystems.BaseEventData eventData, UnityEngine.EventSystems.EventFunction`1 functor) (at C:/buildslave/unity/build/Extensions/guisystem/UnityEngine.UI/EventSystem/ExecuteEvents.cs:269)
 UnityEngine.EventSystems.EventSystem:Update()

And it claims that the error is on the line that says:

 s.button = g.GetComponent<Button>();

Thank you in advance for your help! - Tiger27

Answer 1

Best Answer

Answer by Mikilo · Jan 14, 2017 at 11:34 PM

Hello!

Your case is explicit.

If the error is on the line:

 s.button = g.GetComponent<Button>();

The null object is either s or g.

It would be surprising that s is null.

I would bet on g, if ButtonPrefab is wrong or null.

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JamesGameDev · Jan 15, 2017 at 01:31 PM 1

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@$$anonymous$$ikilo Thanks for the answer. The problem was, I had made the ButtonPrefab a Button, and not a GameObject, meaning it was trying to access the Button component of a Button component, whcih obviously doesn't work, and therefore returned the error. The fix:

 s.button = g;

Thanks, and have a nice day!

Mikilo JamesGameDev · Jan 15, 2017 at 01:45 PM 0

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Have a nice day. :)

Why does this Instantiate give a Null Reference Exception?

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