Array returning null

Question

I have an array of game objects that I'm trying to search through to get a reference to the one named but I keep getting returned a null and I'm not sure why. I'm a beginner at programming so please temper your answer toward a beginner's understanding, many thanks.

 using System.Linq;
 using UnityEngine;
 using System.Collections;
 using System.Collections.Generic;
 
 public class ItemManager : MonoBehaviour
 }
   public Item[] Items;
 
   void Start ()
 {
 for (int i = 0; i < Items.Length; i++)
     {
       Debug.Log ("Item Name: " + Items[i].Name);
     }
 }
 
 //gets a reference to the item with this name
         public Item GetItemByName(string itemName)
         {
             Debug.Log ("inside GetItemByName looking for: " + itemName);
             return Items.FirstOrDefault(item => item.Name == itemName);
         }
 }

GetItemsByName () is called by another script when the object the other script is attached to is destroyed using OnDestroy ().

Answer 1

Unless you have other code initializing the Items array it will always be null. This would cause a NullPointerException (NPE) in Start() on line 14 and in GetItemByName() on line 22.

You could fix this by initializing Items to some default starting size:

 public class ItemManager : MonoBehaviour
 {
   public Item[] Items = new Item[5]
   ...

If you're using Items as a variable size container I might recommend using System.Collections.Generic.List (http://msdn.microsoft.com/en-us/library/6sh2ey19(v=vs.110).aspx) instead.

Your code would change to something like

 using System.Linq;
 using UnityEngine;
 using System.Collections.Generic;
  
 public class ItemManager : MonoBehaviour
 {
     // the main difference from using an array is the declaration and initialization
     // of Items here.
     public List<Item> Items = new List<Item>();
  
     void Start ()
     {
         for (int i = 0; i < Items.Count; i++)
         {
             Debug.Log ("Item Name: " + Items[i].Name);
         }
     }
  
     // gets a reference to the item with this name
     public Item GetItemByName(string itemName)
     {
         Debug.Log ("inside GetItemByName looking for: " + itemName);
         return Items.FirstOrDefault(item => item.Name == itemName);
     }
 }

Array returning null

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