Question Null reference exception: an object reference is required for the non static field error

Hi!
I am new to Unity. I get this error in my first script in Desk.AddForce(10) and it doesn't perform what it should from the second script. Can you help me?
Thanks in advance!

Code (CSharp):

1. public class rock_collision : MonoBehaviour
2. {
3.     public static Desk Desk;
4.     public GameObject obj;
5.     void Start()
6.     {
7.         obj.SetActive(false);
8.     }
9.     void show()
10.     {
11.         obj.SetActive(true);
12.     }
13.     private void OnTriggerEnter(Collider other)
14.     {
15.         if (other.gameObject.tag == "Player")
16.         {
17.             show();
18.             Desk.AddForce(10);
19.         }
20.     }
21. }
22.  

Code (CSharp):

1. public class Desk: MonoBehaviour
2. {
3.     public void AddForce(int damage)
4.     {
5.        GetComponent<Rigidbody>().AddForce(Vector3.up * damage, ForceMode.VelocityChange);
6.     }
7.  
8. }

 

Your desk field is not initialized, it is null

 

Null reference DOES NOT require a forum post, ever. Why?

Because the answer is always the same... ALWAYS. It is the single most common error ever. It's less than a typo.

Don't waste your life spinning around and round on this error. Instead, learn how to fix it fast... it's EASY!!

Some notes on how to fix a NullReferenceException error in Unity3D
- also known as: Unassigned Reference Exception
- also known as: Missing Reference Exception
- also known as: Object reference not set to an instance of an object

http://plbm.com/?p=221

The basic steps outlined above are:
- Identify what is null
- Identify why it is null
- Fix that.

Expect to see this error a LOT. It's easily the most common thing to do when working. Learn how to fix it rapidly. It's easy. See the above link for more tips.

This is the kind of mindset and thinking process you need to bring to this problem:

https://forum.unity.com/threads/why-do-my-music-ignore-the-sliders.993849/#post-6453695

Step by step, break it down, find the problem.