Getting error CS0120

Questions & Answers
1

Hi, this is my first time asking a question here but it’s something that has really stumped me. I’m sort of new to Unity and have been having a hard time finding any tutorials dealing with C# so I’ve had to convert from Java.

Anyway in the code I’ve been working on for a health bar I’ve been getting this error message: Assets/Scripts/GUI Scripts/healthBar.cs(144,35): error CS0120: An object reference is required to access non-static member `healthBar.changeTexture(int)’

Here is the full code:
using UnityEngine;
using System.Collections;
using System.Collections.Generic;

public class healthBar : MonoBehaviour
{
	
PlayerAttributes playerA;
	
public healthBar SwitchGUI;
	
healthBar healthObj;
powerBar powerObj;
	
public int startHealth = 4;
public int maxHealth = 8;
public bool destroyOnDeath = false;
public bool onHitDie = false;
private float lastHit = 0.0f;
public bool dead = false;
	
public Collider hit;
	
public List<Texture> switchableTextures = new List<Texture>();
public int currentTexture = 0;
	
//public Texture healthTex;
private Texture texture;
	
public Texture2D healthTex;
public Texture2D powerTex;
	


	// Use this for initialization
	void Start ()
	{
		
		if (switchableTextures.Count > 0) 
		{
			texture = switchableTextures[currentTexture];
		}
		
		playerA = PlayerAttributes.GetInstance();
		if(!healthObj)
		{
			healthObj = GameObject.FindGameObjectWithTag("Player").GetComponent<healthBar>();
		}
		
		playerA = PlayerAttributes.GetInstance();
		if(!powerObj)
		{
			powerObj = GameObject.FindGameObjectWithTag("Player").GetComponent<powerBar>();
		}
		
		//Texture2D healthTex = new Texture2D(128,128);
		//renderer.material.mainTexture = healthTex;
		
		maxHealth = startHealth;
	
	}
	
		
	public void changeTexture(int switchTo) 
	{
		if (switchTo < switchableTextures.Count && switchTo >= 0) 
		{
			texture = switchableTextures[switchTo];
			currentTexture = switchTo;
		} 

	}
	
		void up() 
	{
		if ((currentTexture+1) < switchableTextures.Count) 
		{
			++currentTexture;
			texture = switchableTextures[currentTexture];
		} 

	}
	
	void nextTexture() 
	{
		if ((currentTexture+1) < switchableTextures.Count) 
		{ // if we are at the end of the array
			++currentTexture;
			texture = switchableTextures[currentTexture];
		} 
		else 
		{// loop to the beginning
			currentTexture = 0;
			texture = switchableTextures[currentTexture];
		}
	}
	
	void down() 
	{
		if ((currentTexture-1) >= 0) 
		{
			--currentTexture;
			texture = switchableTextures[currentTexture];
		} 

	}
	
	
	void StartGame() 
	{
		
		dead = false;
		startHealth = maxHealth;
		
	}
	
	public int currentHealth()
	{
	
		return startHealth;
		
	}


	void PlayerHit() 
	{
		/*if(onHitDie) 
		{
			Dies();
		}*/
		
		int damage = startHealth-1;
		
		startHealth -= damage;
		startHealth = Mathf.Clamp(startHealth,0,maxHealth);
		float lastHit = Time.time;
	}
	
	// Update is called once per frame
	void Update ()
	{
		if(Input.GetKey("b"))
		{
			healthBar.changeTexture(healthObj.currentHealth);
		}

		/*if (startHealth == 0)
		{
			//int startHealth = -1;
			Dies();
		}*/

	}

	/*void Dies() 
	{
		
		dead = true;
	
		if (destroyOnDeath) 
		{
			Destroy(this.gameObject);
		}
	}*/
	
	void OnGUI()
	{
		//Draw the power bar
		Rect rect = new Rect(0,0,Screen.width/3, Screen.height/10);
		GUI.Button(rect, healthTex);	
		rect.y += rect.height;
		GUI.Button (rect, powerTex);
		rect.y += rect.height;
	}

}

And this is the section that generates the error:

	// Update is called once per frame
	void Update ()
	{
		if(Input.GetKey("b"))
		{
			healthBar.changeTexture(healthObj.currentHealth); // This line
		}

		/*if (startHealth == 0)
		{
			//int startHealth = -1;
			Dies();
		}*/

	}

I have no idea what is wrong and it’s driving me crazy! Any help would be appreciated, thanks!

2

healthBar.changeTexture(healthObj.currentHealth); // This line

should just be

changeTexture(healthObj.currentHealth);

You should not be calling the script name. Also for clarity although not strictly a problem, all class names should start with a capital letter and all Methods should start with a capital letter, example:

public class healthBar : MonoBehaviour should be public class HealthBar : MonoBehaviour
and
public void changeTexture(int switchTo) should be public void ChangeTexture(int switchTo)

Small edit: you have a few major errors in your code, for example this:

float lastHit = Time.time;

and you have
private float lastHit = 0.0f; as a field. This is wrong. I assume you would want to just do lastHit = Time.time;

Another edit: You have even more serious problems.

Now i think i fixed it in the way i see how it should work. If it is not how i think it should work, then the script is completely wrong, and you should rethink it.

public class HealthBar : MonoBehaviour
{

    PlayerAttributes playerA;

    public healthBar SwitchGUI;

   // HealthBar healthObj;
    powerBar powerObj;

    public int startHealth = 4;
    public int maxHealth = 8;
    public bool destroyOnDeath = false;
    public bool onHitDie = false;
    private float lastHit;
    public bool dead = false;

    public Collider hit;

    public List<Texture> switchableTextures = new List<Texture>();
    public int currentTexture = 0;

    //public Texture healthTex;
    private Texture texture;

    public Texture2D healthTex;
    public Texture2D powerTex;



    // Use this for initialization
    void Start()
    {

        if (switchableTextures.Count > 0)
        {
            texture = switchableTextures[currentTexture];
        }


        /*
         * Do you really need this? I mean is this script already attached to the player?
        playerA = PlayerAttributes.GetInstance();
        if (healthObj != null)
        {
            healthObj = GameObject.FindGameObjectWithTag("Player").GetComponent<healthBar>();
        }
        */

        playerA = PlayerAttributes.GetInstance();
            if (powerObj != null)
            {
                powerObj = GameObject.FindGameObjectWithTag("Player").GetComponent<powerBar>();
            }

        //Texture2D healthTex = new Texture2D(128,128);
        //renderer.material.mainTexture = healthTex;

        maxHealth = startHealth;

    }


    public void ChangeTexture(int switchTo)
    {
        if (switchTo < switchableTextures.Count && switchTo >= 0)
        {
            texture = switchableTextures[switchTo];
            currentTexture = switchTo;
        }

    }

    void Up()
    {
        if ((currentTexture + 1) < switchableTextures.Count)
        {
            currentTexture++;
            texture = switchableTextures[currentTexture];
        }

    }

    void NextTexture()
    {
        if ((currentTexture + 1) < switchableTextures.Count)
        { // if we are at the end of the array
            currentTexture++;
            texture = switchableTextures[currentTexture];
        }
        else
        {// loop to the beginning
            currentTexture = 0;
            texture = switchableTextures[currentTexture];
        }
    }

    void Down()
    {
        if ((currentTexture - 1) >= 0)
        {
            currentTexture--;
            texture = switchableTextures[currentTexture];
        }

    }


    void StartGame()
    {

        dead = false;
        startHealth = maxHealth;

    }

    public int  CurrentHealth()
    {

        return startHealth;

    }


    void PlayerHit()
    {
        /*if(onHitDie) 
        {
          Dies();
        }*/

        int damage = startHealth - 1;

        startHealth -= damage;
        startHealth = Mathf.Clamp(startHealth, 0, maxHealth);
        lastHit = Time.time;
    }

    // Update is called once per frame
    void Update()
    {
        if (Input.GetKey("b"))
        {
            ChangeTexture(CurrentHealth());
        }

        /*if (startHealth == 0)
        {
          //int startHealth = -1;
          Dies();
        }*/

    }

    /*void Dies() 
    {
 
       dead = true;
 
       if (destroyOnDeath) 
       {
         Destroy(this.gameObject);
       }
    }*/

    void OnGUI()
    {
        //Draw the power bar
        Rect rect = new Rect(0, 0, (float)Screen.width / 3, (float)Screen.height / 10);
        GUI.Button(rect, healthTex);
        rect.y += rect.height;
        GUI.Button(rect, powerTex);
        rect.y += rect.height;
    }

}