UI Toggle Issue: NullReferenceException

I have a script that changes child text on a toggle ui object. It works, but it keeps on throwing an error
"
NullReferenceException: Object reference not set to an instance of an object
ToggleText.Update () (at Assets/Scripts/ToggleText.cs:18)
"

I would like to fix the error, and then also see if I can get advice on how change it so it doesn't check every frame, but instead only switches the text when the bool state is changed.

Script is

Code (CSharp):

1. using UnityEngine;
2. using UnityEngine.UI;
3.  
4. public class ToggleText : MonoBehaviour
5. {
6.     Toggle ui_Toggle;
7.     public Text ui_Text;
8.     public string A;
9.     public string B;
10.  
11.     void Start()
12.     {
13.         ui_Toggle = GetComponent<Toggle>();
14.     }
15.  
16.     void Update()
17.     {
18.         if (ui_Toggle.isOn)
19.         {
20.             ui_Text.text = A;
21.         }
22.  
23.         else
24.         {
25.             ui_Text.text = B;
26.         }
27.     }
28. }
29.  

Thanks

 

The only way it throws a null error on line 18 is if ui_Toggle is null.

As far as not doing this in Update, if you take a look at the Toggle component, it has an On Value Changed event. You can hook in this event so when the value changes, it calls a method.

 

So, if ui_Toggle is null, why is it null? and how do I make it not null. My assumption was that ui_Toggle was the toggle ui component, and it was getting the value from that successfully (In that the script was working, and the text is toggling as I was expecting). If I make ui_Toggle public and simply drag the toggle object into it, I still get the same error. I am very inexperienced with this, so I am probably missing something basic, but I seem to be missing it for sure.
thanks

 

Are you sure you don't have a duplicate of the script on another object in the scene that doesn't have a toggle component on it?

 

Try adding `[RequireComponent(typeof(Toggle))]` just before `public class ToggleText`, and see what happens in your editor.

 

There was in fact a duplicate of the script hiding on another object in the scene. Usually it is me doing something dumb. Thanks!

L:F

 

No problem, glad you found it. I would still suggest you look into the On Value Changed Event on the toggle instead of using Update as well.