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C# Object Reference not set to an instance of an object

Hello, today I tried to make a healing potion for my first game. I've made 2 methods, UpdateUI() and HealPlayer(). When you click on the healing potion in the inventory, a button component calls the "HealPlayer()"-function. Everything works fine, but when I click on the potion, I get an error "Object Reference not set to an instance of an object ". I've seen many people having this problem, but no solution worked for my problem. Can someone help me? Thank you.


Comments

  • Usually that error is received when not all variables in the inspector have been filled. Do you have 'potion' variable or something like that that you just need to put a reference into?

  • As @Etonio99 said, there is probably a reference that you are missing. As I see, "HealthText" is public, so you would want to drag and drop the specific object from the Hierarchy to the desired reference in Inspector.

  • MoodieMoodie Member

    Did you say using UnityEngine.UI;;on the top of the page?

  • An Object is an instance of a Class , it is stored some where in memory. A reference is what is used to describe the pointer to the memory location where the Object resides. The message "object reference not set to an instance of an object" (NullReferenceException) means that you are referring to an object the does not exist or was deleted or cleaned up. In order to prevent the error, objects that could be null should be tested for null before being used.


    if (mClass != null)

    {

     // Go ahead and use mClass

     mClass.property = ...

    }

    else

    {

     // Attempting to use mClass here will result in NullReferenceException

    }


    A NullReferenceException typically reflects developer error and is thrown in the following scenarios:


    • Forgotten to instantiate a reference type.
    • Forgotten to dimension an array before initializing it.
    • Is thrown by a method that is passed null.
    • Get a null return value from a method, then call a method on the returned type.
    • Using an expression to retrieve a value and, although checking whether the value is null.
    • Enumerating the elements of an array that contains reference types, and attempt to process one of the elements.


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