Other script function call with variables

I have class A with prefab populated from inspector. I’d like to call it from class B. I call it like below and got NullReference exception for Class’s A prefabButton being null.
How can I can the method from another class using destination class properties populated via inspector.

public class A: MonoBehaviour {
    public GameObject prefabButton;
    public void FunctionA()
      GameObject newButton = Instantiate(prefabButton) as GameObject;

public class B: MonoBehaviour
    public void FunctionB()
        A populator = new A();

It will be null, because you didn’t assigned no game object to prefabButton. Your problem is that you are trying to create a MonoBehaviour with the new keyword instead of getting it as component. MonoBehaviour must be added to a game object and then the instance of the script is retreived through GetComponent().

  1. Create a new object in the hierarchy name it ObjectA and add the A component to it.
  2. Drag and drop your game object which you want to populate over the prefabButton inspector field.
  3. Create a new game object in the hierarchy and add component B to it.
  4. In class B’s method FunctionB() instead of creating “new A()” replace it with: GameObject.Find(“ObjectA”).GetComponent().FunctionA();