UnityEvent.AddListener throwing nullReferenceException

Hello There!

I'm trying to implement unity events to my game, but when I add a listener from code I get a nullReferenceException on the AddListener line, for some reason.

The relevant code

Code (CSharp):

1. public class Player : MonoBehaviour
2. {
3. private void Start() {
4.             onRecoil.AddListener(cameraController.ApplyImpulse);
5. }
6.  
7. public class RecoilEvent : UnityEvent<Vector2> {}
8. public RecoilEvent onRecoil;
9.  
10. private void Fire() {
11.        Vector2 recoil = currentWeapon.Fire();
12.         if (recoil == -Vector2.one)
13.             return;
14.  
15.         if(onRecoil != null)
16.             onRecoil.Invoke(recoil);
17. }
18. }

Any help is much appreciated

 

Where are you declaring and assigning the

cameraController

variable?

 

It is declared in the Player class, and assigned in the inspector, I checked it multiple times, it is assigned.

 

Debug.Log right before line 4 the values of

onRecoil

and

cameraController

. One of those two is null:

Code (CSharp):

1. Debug.Log($"onRecoil is: {onRecoil}, cameraController is: {cameraController}");

One possibility also is that you have multiple copies of this script in your scene by accident, one of which is not configured properly.

 

I got back only 1 log entry

onRecoil is: , cameraController is: CameraControls (CMF.CameraController)

UnityEngine.Debug:Log(Object)

FPS.Gameplay.Player:Start() (at Assets/Scripts/Player.cs:28)

 

Based on your log,

onRecoil

is null.

 

That is odd, as you can see in the script I shared, onRecoil is a UnityEvent. I'm new to the UnityEvent system, maybe I'm missing something? Should I assign something to onRecoil?

 

What's showing in the inspector? Try this perhaps?

Code (CSharp):

1. public RecoilEvent onRecoil = new RecoilEvent();

 

You might also have to write a zero-arg constructor for RecoilEvent which calls UnityEvent's zero-arg constructor:

Code (CSharp):

1. public class RecoilEvent : UnityEvent<Vector2> {
2.   public RecoilEvent : base() { }
3. }

 

Yes thank you, that solved it, I feel so silly...