[Question] Help, I can't access to a method from a another class..

Hello Everybody,

Sorry for my english, I'm french but french unity forums are generally dead ( or less active ).

I have a big problem who is the following :

I've two Objects : a ball object and a bar object who have each their respective script.

Here is my ball.cs class :

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class ball : MonoBehaviour
6. {
7.  
8.     public float mVelocity = 0.6f;
9.  
10.     public Rigidbody2D rb;
11.  
12.     // Start is called before the first frame update
13.     void Start()
14.     {
15.         rb = GetComponent<Rigidbody2D>();
16.         rb.velocity = new Vector2(Random.Range(0.5f, 0.8f)*mVelocity, Random.Range(0.5f, 0.8f)*mVelocity);
17.     }
18.  
19.     // Update is called once per frame
20.     void Update()
21.     {
22.         rb.velocity = mVelocity * rb.velocity.normalized;
23.     }
24.  
25.     public Vector2 getCenterBall()
26.     {
27.         return rb.centerOfMass;
28.     }
29. }
30.  

Here is my bar.cs class :

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class bar : MonoBehaviour
6. {
7.  
8.     private float mVelocity = 10f;
9.     public ball b;
10.  
11.     // Start is called before the first frame update
12.     void Start()
13.     {
14.         b = GetComponent<ball>();
15.     }
16.  
17.     // Update is called once per frame
18.     void Update()
19.     {
20.          MouseBarRotation();
21.      }
22.  
23.     void MouseBarRotation()
24.     {
25.         Vector2 test = b.getCenterBall();
26.         print(test.x);
27.     }
28.  
29. }
30.  

As you can see, in my bar.cs class I try to call the method getCenterBall() of my ball that I've instancied with the name "b" at the beginning but when I launch my program, I have the following error :

Code (CSharp):

1. NullReferenceException: Object reference not set to an instance of an object
2. bar.MouseBarRotation () (at Assets/Scripts/bar.cs:25)
3. bar.Update () (at Assets/Scripts/bar.cs:20)

This error pointed the following line of my bar.cs class :

Code (CSharp):

1.         Vector2 test = b.getCenterBall();

I joined a screenshot to this thread to show you my project arborescence.

I lost 2 hours with full google and youtube searching and all solutions I found didn't work.. It make me crazy

Thanks a lot for my future lifesaver