Can't subscribe listeners to an Event.

I have created an event that will run when an interactable object enters the radius of the player, but when attempting to subscribe other scripts to the events I get this error: NullReferenceException: Object reference not set to an instance of an object.

I thought at first it was a was a script execution order error and the other scripts were calling on the singleton instance before it was set, but when I changed the order to be sure the instance was first establish the error persisted. I found a thread with a similar problem here: https://forum.unity.com/threads/why-can-i-not-subscribe-to-an-event-of-a-singleton.838417/
but they gave up on trying to find a solution.

This is my event handler script:

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4. using System;
5. //System is require to used GameEvents
6.  
7. public class GameEvents : MonoBehaviour
8. {
9.     /*
10.     This is the Custom Event System.
11.     This Script will contain ways to notify other scripts when an event occours.
12.     Events like playerdeath, when a player can interact, or the end of a round.
13.     All objects that react to events will need access to this script.
14.     There can only be one instance of this object
15.     This helps reduce the amount of dependancies
16.     -S
17.     */
18.  
19.     //This is the refference to the script.
20.     public static GameEvents current;
21.  
22.     private void awake()
23.     {  
24.         current = this;
25.      
26.     }
27.  
28.     //This is the Event to allow the player to Interact
29.     public event Action onInteractionRadiusEnter;
30.     //This is the Fuction of that Event that notifies the other scripts the radius has been entered
31.     public void interactionRadiusEnter()
32.     {  
33.         if(onInteractionRadiusEnter != null)
34.         {
35.             onInteractionRadiusEnter();
36.             Debug.Log("interaction radius entered");
37.         }
38.     }
39.  
40.     public event Action onInteractionRadiusExit;
41.  
42.     public void interactionRadiusExit()
43.     {
44.         if(onInteractionRadiusExit != null)
45.         {
46.            onInteractionRadiusExit();
47.         }
48.     }
49. }

and this is the script I am trying to subscribe to the event:

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class PlayerInteraction : MonoBehaviour
6. {
7.     private bool playerCanInteractWithObjects = false;
8.     private GameObject objectToInteractWith;
9.     private Interactable objectInteraction;
10.  
11.     private void Start()
12.     {
13.       GameEvents.current.onInteractionRadiusEnter += playerCanInteract;
14.       GameEvents.current.onInteractionRadiusExit += playerCannotInteract;
15.     }
16.  
17.     //This Triggers the enter event;
18.  
19.  
20.  
21.     public void OnTriggerEnter2D(Collider2D other)
22.     {
23.         if (other.gameObject.CompareTag("Interactable"))
24.         {
25.             objectToInteractWith = other.gameObject;
26.             GameEvents.current.interactionRadiusEnter();
27.             Debug.Log("inteaction raduis entered");
28.         }
29.  
30.     }
31.  
32.     //This triggers the exit Event
33.     public void OnTriggerExit2D(Collider2D other)
34.     {
35.         if (other.gameObject.CompareTag("Interactable"))
36.         {
37.             objectToInteractWith = null;
38.             GameEvents.current.interactionRadiusExit();
39.         }
40.  
41.     }

its worth noting that this error isn't isolated to this script. I've create other scripts just to see if they can subscribe and they cannot. I am completely out of ideas on this one.

 

The singleton instance is null because of this:

Code (CSharp):

1.     private void awake()
2.     {
3.         current = this;
4.    
5.     }

Awake

should be spelled with a capital "A".

On a somewhat unrelated note, you can shorten your event invocations from this...

Code (CSharp):

1. if(someEvent != null)
2. {
3.    someEvent();
4. }

...To this:

Code (CSharp):

1. someEvent?.Invoke();

 

god, thats is embarrassing. Thank you so much mate. I spent 2 hours trying to figure this out

 

Can you please describe how you fixed this? I think I'm having the same problem and I'm too much of a noob to solve it.

 

Hello

He write Awake instead of awake.

Christoph