Feedback Yet another NullReferenceException: Object reference not set to an instance of an object

Hi.

I am new to scripting and I am having trouble trying to access a function from another script.

Relevant part of the GameController.cs:

Code (CSharp):

1.     public Slider slider;
2.     public float FillSpeed = 0.5f;
3.     public float targetProgress = 0;
4.  
5.     public void Update () {
6.  
7.         Progressbarupdate();
8.     }
9.  
10.     public void IncrementProgress(float newProgress)
11.     {
12.         Debug.Log("I am here");
13.         targetProgress = slider.value + newProgress;
14.     }
15.  
16.     public void Progressbarupdate()
17.     {
18.         if (slider.value < targetProgress)
19.             slider.value += FillSpeed * Time.deltaTime;
20.     }

Relevant part of the CollectionCoin.cs

Code (CSharp):

1. public class CollectCoins : MonoBehaviour
2. {
3.     GameController GC = new GameController();
4.  
5.     public void OnTriggerEnter(Collider other)
6.     {
7.         if (gameObject.CompareTag("Coin"))
8.         {
9.             GameController.scoreValue += 50;
10.             GC.IncrementProgress(0.75f);
11.             Destroy(gameObject);
12.         }
13.     }
14. }

When I trigger the function in the console I see the "I am here" as a log, so I can see trigger goes to the function but adicionally I receive an error

Code (CSharp):

1. NullReferenceException: Object reference not set to an instance of an object
2. GameController.IncrementProgress (System.Single newProgress) (at Assets/Scripts/Atual/GameController.cs:241)
3. CollectCoins.OnTriggerEnter (UnityEngine.Collider other) (at Assets/Scripts/Atual/CollectCoins.cs:14)

line 241 in GameController is targetProgress = slider.value + newProgress; and line 14 in CollectCoins.cs is GC.IncrementProgress(0.75f);

And I have the Slider attached



Thanks for any help on this.

 

You haven't assigned a Slider to your slider field. You can do so by dragging one from your scene hierarchy onto your GameController component in the slider field.

 

I had it before, just didnt mention it on the post... I just updatet it for future visitors. Thanks...

 

Try changing your log statement to

Code (CSharp):

1. Debug.Log($"Slider is {slider}");

What does that print out?

 

Just Slider is

Code (CSharp):

1. Slider is
2. UnityEngine.Debug:Log(Object)
3. GameController:IncrementProgress(Single) (at Assets/Scripts/Atual/GameController.cs:241)
4. CollectCoins:OnTriggerEnter(Collider) (at Assets/Scripts/Atual/CollectCoins.cs:14)

 

Something is setting your slider to null. Otherwise it would print the name of the GameObject that the Slider is attached to.

Is the slider in your scene, or is it an asset? Also are you certain there is only ONE GameController object in your scene?

 

There is only one reference of this script in the scene. The slider is in the scene, active. Well, I did another test based on your suggestion. I called the function on the same CS file that has the function... and it worked

Code (CSharp):

1. Slider is Slider (UnityEngine.UI.Slider)
2. UnityEngine.Debug:Log(Object)
3. GameController:IncrementProgress(Single) (at Assets/Scripts/Atual/GameController.cs:244)
4. GameController:Update() (at Assets/Scripts/Atual/GameController.cs:93)

But if I call it from another script the error still coming

 

I gave up on this and tried the following asset: https://assetstore.unity.com/packages/tools/gui/simple-health-bar-free-95420 which works great.