UI Images - Object reference not set to an instance of an object

Question

Hi All,

Well, my initial post got zero responses and as a Unity noob I could really use some help. Essentially, I'm not understanding how variables assigned in the Inspector can turn out to be null at runtime.

I had functionality in a class that updated UI images on a canvas. These UI images were public variables that were assigned in the Inspector. It worked wonderfully, but really belonged in its own separate class; so, I created one and changed the original class to reference this new class to duplicate the functionality. However, once I separated it all out, I began getting the above object reference error.

My script bombs out on the following line:

 ScoreboardSlots [i + LeadingBlanks] = Instantiate (Digit0, Digit0.transform.parent);

ScoreboardSlots[whatever] is null, which is probably ok at this point because I'm trying to assign it to something. But, Digit0 is also somehow null even though it's been assigned in the editor as a public variable.

Surely I'm missing something very simple but I'm at a loss. Any advice???

Thanks, Todd

Answer 1

Best Answer

Answer by vanfriscia · Feb 09, 2018 at 05:45 PM

Well I never did solve this, but I did implement a workaround. Instead of assigning my UI images in the Inspector via public variables, I changed them to private and created a new public method to initialize them like in the following example:

 Digit0 = GameObject.Find ("Digit0").GetComponent<Image> ();

This apparently HAS to be in its own method and called from another script; initially I tried putting it in Start() or Awake(), and while it didn't error out, the variables were again null once other methods were called. I still don't get it but maybe this will be helpful to someone, someday!

Add comment · Show 2 · Share

magmorta2012 · Aug 02, 2018 at 11:36 PM 0

Share

Thank you so much, this is exactly what I needed. I have no idea why GetComponent and dragging the image in to reference it was breaking it but this works. Very new to Unity so this was infuriating as I had no idea why the reference was disappearing when I pressed play haha.

vanfriscia magmorta2012 · Aug 08, 2018 at 11:47 AM 1

Share

I can relate to the fury my friend! But I'm glad to know that this post ended up helping SO$$anonymous$$EBODY even if it didn't help me :). Good luck!

Answer 2

Answer by alti · yesterday

It's impossible to help you to debug without the script to look at. I'm only going to therefore assume what your problem is:

If you just write the variable as:

 GameObject[] ScoreBoardSlots;

You cannot fill it.

 void Start(){
 ScoreBoardSlots[0] = not allowed.
 }

You're trying to fill an array but you don't show us if the array was initialized. If an array isn't initialized, you cannot fill the numbered slot you listed above.

 private GameObject[] ScoreBoardSlots = new GameObject[2];
 void Start(){
 ScoreBoardSlots[0] = whateverGameObjectYouWant;
 }

Then you can fill it.

If this isn't/wasn't your issue, then you need to share more of the code.

Add comment · Share

UI Images - Object reference not set to an instance of an object

2 Replies

Your answer

Follow this Question

Related Questions