C# Children and SubChildren Null Reference Exception

Question

Hi everyone, in one of my scripts I'm getting a null reference exception and I'm trying to figure out why. The console says it's coming from line 9. I have two Transform Arrays someTransformArray1 and someTransformArray2. Both of them have children and subchildren. I want to make it so someTranformArray1's subchildren's sharedMesh equals someTranformArray2's subchildren's sharedMesh. Any idea what is causing this null reference exception?

 public Transform[] someTransformArray1;
 public Transform[] someTransformArray2;
 
 void Awake(){
     foreach (Transform child1 in someTransformArray1)
     foreach (Transform child2 in someTransformArray2)
     foreach (Transform subchild1 in child1)
     foreach (Transform subchild2 in child2)
     subchild1.GetComponent<MeshFilter>().sharedMesh = subchild2.GetComponent<MeshFilter>().sharedMesh;
 }

Answer 1

Best Answer

Answer by Em3rgency · Jun 29, 2013 at 09:10 PM

Add an

 if(subchild1 != null && subchild2 != null)

right above line 9, and you will be dandy. (It wont change the fact that this does not find any subchild1/2 in childCurrent or childOriginal, but it will get rid of that error)

Also, you seem to be running a cycle in a cycle in a cycle in a cycle. Are you SURE that's what you wan't to be doing?

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Ochreous · Jun 29, 2013 at 09:16 PM 0

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I need to access children of children so yes. I do think this way of finding them is rather redundant. Do you know an easier and more efficient way of doing this?

Em3rgency · Jun 29, 2013 at 09:22 PM 0

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Well, no, that's about right, but children of children would only get you 2 levels (1 loop for the children of the object, second loop inside that for the children of children). Not full blown 4. :)

Ochreous · Jun 29, 2013 at 09:30 PM 0

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I'm still getting the null reference Exception.

 public Transform[] someTransformArray1;
 public Transform[] someTransformArray2;
  
 void Awake(){
 foreach (Transform child1 in someTransformArray1)
 foreach (Transform child2 in someTransformArray2)
 foreach (Transform subchild1 in child1)
 foreach (Transform subchild2 in child2)
 if(subchild1 != null && subchild2 != null)
 subchild1.GetComponent<$$anonymous$$eshFilter>().shared$$anonymous$$esh = subchild2.GetComponent<$$anonymous$$eshFilter>().shared$$anonymous$$esh;
 }

Em3rgency · Jun 29, 2013 at 09:39 PM 0

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Ok wait, do you create the someTransformArray1 and someTransformArray2 anywhere? Just declaring it like that is not enough.

Ochreous · Jun 29, 2013 at 11:17 PM 0

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I found what was causing the Null Reference exception. I needed to check if subchild1 and subchild2s' $$anonymous$$eshFilters were null not the subchildren themselves.

 if(subchild1.GetComponent<$$anonymous$$eshFilter>() != null && subchild2.GetComponent<$$anonymous$$eshFilter>() != null)

C# Children and SubChildren Null Reference Exception

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