My Script isn't working

Unity Engine
1 
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class ItemShop : MonoBehaviour
{

    public static ItemShop itemShop;

    public List<Items> itemList = new List<Items>();

    public GameObject itemHolderPrefab;
    public Transform grid;

    void Start()
    {
        itemShop = this;
        FillList();
    }

    void FillList()
    {
        for (int i = 0; i < itemList.Count; i++)
        {
            GameObject holder = Instantiate(itemHolderPrefab,grid);
            ItemHolder holderScript = holder.GetComponent<ItemHolder>();

            holderScript.itemName.text = itemList[i].itemName;
            holderScript.itemPrice.text = itemList[i].weaponPrice.ToString("N2") + " Gems";
            holderScript.itemID = itemList[i].itemID;


            holderScript.buyButton.GetComponent<BuyButton>().itemID = itemList[i].itemID;


            if (itemList[i].bought)
            {
                holderScript.itemImage.sprite = itemList[i].boughtSprite;
            }
            else
            {
                holderScript.itemImage.sprite = itemList[i].unboughtSprite;
            }
        }
    }
    void Update()
    {
       
    }
}

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.SceneManagement;
using TMPro;
using UnityEngine.UI;

public class GameManager : MonoBehaviour
{

    public GameObject GameOverPanel;
    public GameObject LevelCompletePanel;
    public TextMeshProUGUI currentScoreText;
    public GameObject PauseButtons;
    public GameObject Pausemenu;
    public TextMeshProUGUI currentScoreText2;

    float currentScore;
    float currentScore2;

    public string nextLevel = "2";
    public int levelToUnlock = 2;

    public static GameManager gameManager;

    [SerializeField] private float money;
   

    public TextMeshProUGUI moneyText;

   


    void Start()
    {
        currentScore = 0;
        SetScore();
        currentScore2 = 0;
        gameManager = this;
        //money = 0;
        //UpdateUI();
       
    }


    void Update()
    {
        //money = currentScore;
        UpdateUI();
    }


    public void CallGameOver()
    {
        StartCoroutine(GameOver());

    }

    public void CallGameOver2()
    {
        StartCoroutine(GameOver2());

    }


    public void CallLevelComplete()
    {
        StartCoroutine(LevelComplete());

    }


    IEnumerator GameOver()
    {
        yield return new WaitForSeconds(1f);
        GameOverPanel.SetActive(true);
        PauseButtons.SetActive(false);
        Destroy(Pausemenu);
        yield break;

    }

    IEnumerator GameOver2()
    {
        yield return new WaitForSeconds(1f);
        GameOverPanel.SetActive(true);
        PauseButtons.SetActive(false);
        Destroy(Pausemenu);
        yield break;

    }


    IEnumerator LevelComplete()
    {
        yield return new WaitForSeconds(1f);
        LevelCompletePanel.SetActive(true);
        PauseButtons.SetActive(false);
        Destroy(Pausemenu);
        yield break;

    }



    public void Restart()
    {
        SceneManager.LoadScene(SceneManager.GetActiveScene().buildIndex);

    }

    public void Restart2()
    {
        SceneManager.LoadScene("SampleScene2Player");

    }


    public void Menu()
    {
        SceneManager.LoadScene("Start Menu");
    }

    public void GreyGem()
    {
        currentScore += 1f;
        SetScore();
    }

    public void BlueGem()
    {
        currentScore += 5f;
        SetScore();
    }


    public void GoldGem()
    {
        currentScore += 10f;
        SetScore();
    }

    public void AddMoney(float amount)
    {
        money += amount;
        UpdateUI();
    }


        public void ReduceMoney(float amount)
    {
        money -= amount;
        UpdateUI();
    }

    public bool RequestMoney(float amount)
    {
        if(amount <= money)
        {
            return true;
        }
        return false;

    }

    void UpdateUI()
    {
        moneyText.text = "Gems: " + money.ToString("N2") ;
    }



    public void SetScore()
    {
        currentScoreText.text = currentScore.ToString();
        currentScoreText2.text = currentScore2.ToString();
    }

    public void WinLevel()
    {
        Debug.Log("Level Completed");
        PlayerPrefs.SetInt("levelReached", levelToUnlock);

    }




}

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

public class BuyButton : MonoBehaviour
{
    public int itemID;

    public void BuyItem()
    {
        if (itemID == 0)
        {
            Debug.Log("NO ITEM WITH THAT ID");
            return;
        }

        for(int i = 0; i < ItemShop.itemShop.itemList.Count; i++)
        {
            if(ItemShop.itemShop.itemList[i].itemID == itemID && !ItemShop.itemShop.itemList[i].bought && GameManager.gameManager.RequestMoney(ItemShop.itemShop.itemList[i].weaponPrice))
            {
                ItemShop.itemShop.itemList[i].bought = true;
                GameManager.gameManager.ReduceMoney(ItemShop.itemShop.itemList[i].weaponPrice);
                return;
            }
        }
    }
}

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

[System.Serializable]
public class Items
{
    public string itemName;
    public int itemID;

    public Sprite unboughtSprite;
    public Sprite boughtSprite;

    public float weaponPrice;
    public bool bought;
}

    public int itemID;
    public TextMeshProUGUI itemName;
    public TextMeshProUGUI itemPrice;
    public Image itemImage;
    public GameObject buyButton;

the problem it keeps bringing up anytime i click the buy button is this:
NullReferenceException: Object reference not set to an instance of an object
BuyButton.BuyItem () (at Assets/ShopSystem Script/BuyButton.cs:19)

2

That error points to this line:

if(ItemShop.itemShop.itemList[i].itemID == itemID && !ItemShop.itemShop.itemList[i].bought && GameManager.gameManager.RequestMoney(ItemShop.itemShop.itemList[i].weaponPrice)

To debug this, or just for better readability and organization, try splitting it up into multiple lines:

Items item = ItemShop.itemShop.itemList[i];

bool itemMatchesID = item.itemID == itemID;
bool itemIsNotBought = !item.bought;
bool hasEnoughMoney = GameManager.gameManager.RequestMoney(item.weaponPrice);

if(itemMatchesID && itemIsNotBought && hasEnoughMoney)
{
...

That should tell you a lot more about what is null.

For future reference, please give your posts a more descriptive title.

3

I ran it and the main problem is line 5 so something in the Gamemanager scriptbool hasEnoughMoney = GameManager.gameManager.RequestMoney(item.weaponPrice);

4

Then it looks like your “gameManager” instance is null, because the only other thing is “item”, and if that were null it would error on a previous line.

5

Yes Thank you. You were right and I solved the problem thanks

1 Like