Null Reference Exception - Found the exception, but isn't this supposed to be null?

Ok, so I understand what a Null Reference Exception is. I even know exactly where mine is happening.

I have a moving object, casting a ray a few feet ahead of it. When it hit's the player, then the alarm is raised, which makes the object run towards the player. So up until the ray hits the Player, it's NULL, which obviously gives the Null Reference Exception error. So my question is, how do I deal with it being null up until the point that it finds the player? Do I just manually set it to something else?

The error gets thrown in line 8 where I check if the ray has hit the object named "Character".

Here's my code where the error happens:

Code (csharp):

1. void Alert()
2.     {
3.         //Ray2D ray;
4.         RaycastHit2D hit = Physics2D.Raycast(transform.position, Vector2.right, 5, collisionMask);
5.         Debug.DrawLine(transform.position, new Vector3(transform.position.x + 5,transform.position.y,transform.position.z));
6.         if(hit != null)
7.         {
8.             if(hit.collider.name == "Character")
9.             {
10.                 Debug.Log("Ray has hit: " + hit.collider.name);
11.                 alerted = true;
12.             }
13.         }
14.         else
15.         {
16.             Debug.Log("Player Not Found");
17.         }
18.  
19.     }

 

The 'hit' is never null (since the Raycast initializes it). You actually want to check hit.collider instead:

if ( hit.collider != null ) { stuff; }

 

Physics2D.Raycast returns a RaycastHit2D object only if a collider is hit by the ray, otherwise it returns null.

 

It should also be noted that RaycastHit2D is a struct, so therefore can never be null (unless your variable was typed as a Nullable<T>, or T? for short).

 

I haven't used the 2d physics in Unity yet, but I know that RaycastHit2d is a struct... I just checked.

I also just looked that the Physics2d.Raycast method is shaped differently from the 3d Physics.Raycast. In the 3d Physics class it uses an 'out' parameter and returns a bool on success... because RaycastHit is a struct.

I do NOT know why unity decided to not have the same shape for the 2d physics raycast method. Unless they override the equality operator to test against null correctly. Which is kind of weird, and is inconsistent with their 3d physics API. As well as obfuscates the way structs are supposed to work.

Shame on unity for that bad design there.

[edit]

metadata of the struct:

Code (csharp):

1.  
2. #region Assembly UnityEngine.dll, v0.0.0.0
3. // C:/Program Files (x86)/Unity/Editor/Data/Managed/UnityEngine.dll
4. #endregion
5.  
6. using System;
7.  
8. namespace UnityEngine
9. {
10.     public struct RaycastHit2D
11.     {
12.  
13.         public static implicit operator bool(RaycastHit2D hit);
14.  
15.         public Collider2D collider { get; }
16.         public float fraction { get; set; }
17.         public Vector2 normal { get; set; }
18.         public Vector2 point { get; set; }
19.         public Rigidbody2D rigidbody { get; }
20.         public Transform transform { get; }
21.  
22.         public int CompareTo(RaycastHit2D other);
23.     }
24. }
25.  

... I'm noticing from the metadata it doesn't override the null comparison. But it does have an implicit bool conversion on it. Try something like:

Code (csharp):

1.  
2. if((bool)hit)
3. {
4.     //do stuff
5. }
6.  

 

Thanks! This worked perfectly. It got rid of the error, and behaves exactly as expected. It always seems to be the simple stuff that holds me up...

 

As a side note:
explicit keyword in c#
implicit keyword in c#

explicit requires cast
implicit does not and is technically the point

Code (csharp):

1.  
2. if(hit)
3. {
4.     //do stuff
5. }
6.