Null Exception Reference

I have a NullExcep in this scrip in line 14:
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class UI_Inventory : MonoBehaviour
{
private Inventory inventory;
private Transform itemSlotContainer;
private Transform itemSlotTemplate;

private void Awake()
{
itemSlotContainer = transform.Find("itemSlotContainer");
itemSlotTemplate = itemSlotTemplate.Find("itemSlotTemplate"); //Here is the problem!!!!
}

public void SetInventory(Inventory inventory){
this.inventory = inventory;
RefreshInventoryItems();
}

private void RefreshInventoryItems(){
int x=0;
int y=0;
float itemSlotCellSize = 30f;
foreach (Item item in inventory.GetItemList())
{
RectTransform itemSlotRectTranform = Instantiate (itemSlotTemplate, itemSlotContainer).GetComponent<RectTransform>();
itemSlotRectTranform.gameObject.SetActive(true);
itemSlotRectTranform.anchoredPosition = new Vector2(x * itemSlotCellSize,y * itemSlotCellSize);
x++;
if(x > 4){
x=0;
y++;
}
}
}
}

 

Your problem is that itemSlotTemplate is null because you haven't assigned anything to it yet, but you are trying to call a method on it (Find), this is what causes the error.

It's a bit hard to tell what the correct solution for you is, it depends on where the item you want to find is. If it's a prefab, you most likely want to make your itemSlotTemplate field public (or better, add [SerializeField] to it) and assign the property in the unity inspector.

i.e.

[SerializeField] private itemSlotTemplate;

then select the game object with the script and drag-and-drop your template into the field "Item Slot Template" that should now be visible in the inspector.

 

Thanks, i solve that problem.