(Basic question) NullReferenceException

Hi, iam new to Unity and C#. And such i try to grasp the basics, but i have a hard time getting classes to inherent variables from each other. For example look below.

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class TheOne : MonoBehaviour
6. {
7.     public int theVariable = 1;
8.  
9.     void Start()
10.     {
11.      
12.     }
13. }

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class TheTwo : MonoBehaviour
6. {
7.     TheOne theOne;
8.  
9.     // Start is called before the first frame update
10.     void Start()
11.     {
12.         Debug.Log(theOne.theVariable);
13.        
14.     }
15. }

When i play test i get the error message below.

NullReferenceException: Object reference not set to an instance of an object
TheTwo.Start () (at Assets/Scenes/TheTwo.cs:12)

I cant see what i am doing wrong, as far as I can see i give the int variable a value, but i does not transfer over to the other class.

What am i doing wrong?

 

You need a reference to an actual "TheOne" object, just declaring the variable doesn't mean it's set to one. Since we're using Unity, you can actually just drag the component into the field in the Inspector, but normally in C# you would have to assign it to something first or create one.

 

Thank you!

If someone else facing the same problem here is how i changed the code:

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class TheOne : MonoBehaviour
6. {
7.     public int theVariable = 1;
8.     // Start is called before the first frame update
9.     void Start()
10.     {
11.        
12.     }
13. }

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class TheTwo : MonoBehaviour
6. {
7.     TheOne theOne;
8.  
9.     // Start is called before the first frame update
10.     void Start()
11.     {
12.         theOne = new TheOne();
13.         Debug.Log(theOne.theVariable);
14.     }
15. }