Static method has no access to class variable

Question

Hello, I have the following problem: I have a static method that uses a class variable, but Unity gives me the following error:

\Assets Scripts Gamecontrol.Cs(3,3): Error CS0120: An object reference is required for the field, method or non-static property 'Gamecontrol.healthText' (CS0120) (Assembly-Csharp)

Here is the code from the "Gamecontrol.Cs" script (only relevant code):

using UnityEngine;
using System.Collections;
using UnityEngine.UI;

public class GameControl : MonoBehaviour {

    public Text healthText;
    public static int healthBar = 100;

    public static void UpdateHealthBar(){
        healthText.text = "Health \n" + healthBar;
    }
}

Here is the code of the other file that is calling the method(only relevant):

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class EnemyScript : MonoBehaviour {
void Update(){
        gameObject.transform.Translate (dir.normalized * speed * Time.deltaTime,Space.World);

        if (Vector3.Distance (transform.position, target[wayPoint].position) <= 0.4f) {
            if (wayPoint < target.Length - 1) {
                wayPoint++;
                dir = target [wayPoint].position - gameObject.transform.position;
            } else {
                Destroy (this.gameObject);
                GameControl.healthBar--;
                GameControl.UpdateHealthBar();       //Aqui<<<
            }
        }
    }
}

Well, I realized that instantiating the class in the file to leave the class only public does not get the error, but I want to avoid this solution. Why this error occurs, and how can I resolve?

Answer 1

It is because static members are not part of the object scope, but part of the class.

Assuming there is a class Game with the following members

• string Nome
• string Produtor
• static string Versao

So, Versao will be accessible without instantiating the class

Game.Versao

The other two members will only be accessible in the class instance

Game game = new Game();
game.Nome;
game.Produtor;

A possible solution to your case is to make healthText be also a static member. It seems that this is what you need, since all other members are also static.