What is wrong with my code?

It's just a simple script, I've created an array of transforms and I've assigned the transforms in the editor, when game starts I want to print the name of first transform in the array but I get an error: "NullReferenceException: Object reference not set to an instance of an object"

Code (CSharp):

1. using UnityEngine;
2.  
3. public class ManagerScript : MonoBehaviour {
4.  
5.     [SerializeField]
6.     Transform[] treeHolders;
7.  
8.     // Use this for initialization
9.  
10.     private void Awake()
11.     {
12.      
13.         treeHolders = new Transform[5];
14.  
15.     }
16.    
17.     // Update is called once per frame
18.     void Update () {
19.  
20.         Debug.Log(treeHolders[0].name);
21.        
22.     }
23. }

 

It's an array of Transform "spaces", but there isn't anything in there.
When you make an array of anything, it just says, hey, I have space to hold something, now you need to put something in that space.

So in your case, you have a hotel that has 5 rooms that can hold transforms. But those rooms are empty, so the value returned is null as there isn't anything inside the room. (one way to look at it)

 

I've assigned the transforms in the editor, I even printed the length of the array which it is showing 5.

 

You are overwriting it in Awake, so your values no longer exist.

Remove your line in Awake.

 

I'm new to programming, I learnt that we initialise an array by using the new keyword, right?

 

Yes, but you have to understand Unity works a bit different.

If you declare a collection (like an array) and then go into the inspector and assign values to it, Unity handles initializing it for you. If it didn't do that, you'd run into errors. It basically sets it up for you so it can add values to it.

If you're creating an array yourself and not accessing it in the inspector, you would have to use new to create a new empty array.

 

oooo

ooh, so the line "treeHolders = new Transform[5];" is already being handled by unity and I should remove that line from my script.

 

It worked! Thanks mate!