NullReferenceException: Object reference not set to an instance of an object while declaring an arra

Unity Engine
,
1

I know there is a million threads regarding this topic but I just cant seem to figure out how to solve my issue. I have two scripts. One creates a 2d array and one is the class for the 2d array. But I am getting the error when I am trying to create the array. It did work fine before when I was using the array to hold a single int, but now ive changed it to hold a struct and now this error. The full error is

NullReferenceException: Object reference not set to an instance of an object
GridSystem`1[TGridObject]…ctor (System.Int32 width, System.Int32 height, System.Int32 cellsize, UnityEngine.Vector3 originPosition) (at Assets/scripts/GridSystem.cs:49)
InitialSetup.Start () (at Assets/scripts/InitialSetup.cs:17)

I dont know why its complaining about code at line 49 as there is no code there. But the main issue seems to be with the InitialSetup script;

The two scripts are
GridSystem

using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public struct GridData
{
    public bool isOccupied;
    public bool isBuildable;
}

public class GridSystem<TGridObject>                                                                                   
{
    int gridWidth;
    int gridHeight;

    int cellsize;

    Vector3 originPosition;

    GridData[,] gridArray;

    TextMesh[,] debugArrayText;

    bool isBuildable;
    public GridSystem(int width, int height, int cellsize, Vector3 originPosition)                                                             
    {
        gridWidth = width;
        gridHeight = height;
        this.cellsize = cellsize;
        this.originPosition = originPosition;
        debugArrayText = new TextMesh[gridWidth, gridHeight];

                                                                                   
        gridArray = new GridData[gridWidth, gridHeight];
    } 

}

and the Initial Setup script

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class InitialSetup : MonoBehaviour
{
    GridSystem<GridData> grid;

    float startingPositionX;
    float startingPositionY;
    float aspect = (float)Screen.width / Screen.height;

    private void Start()
    {
        startingPositionY = Camera.main.orthographicSize;
        startingPositionX = startingPositionY * aspect;
        grid = new GridSystem<GridData>(30, 15, 4, new Vector3( -58, -50, 0));       
      

    }
}

If anyone can help me figure out what I am doing wrong here, it would be greatly appreciated.

2

It’s always the same answer:

How to fix a NullReferenceException error

https://forum.unity.com/threads/how-to-fix-a-nullreferenceexception-error.1230297/

Three steps to success:

  • Identify what is null ← any other action taken before this step is WASTED TIME
  • Identify why it is null
  • Fix that

If you THINK you initialized it, the computer begs to differ, which means it is time to start debugging! Here is how you can begin your exciting new debugging adventures:

You must find a way to get the information you need in order to reason about what the problem is.

Once you understand what the problem is, you may begin to reason about a solution to the problem.

What is often happening in these cases is one of the following:

  • the code you think is executing is not actually executing at all
  • the code is executing far EARLIER or LATER than you think
  • the code is executing far LESS OFTEN than you think
  • the code is executing far MORE OFTEN than you think
  • the code is executing on another GameObject than you think it is
  • you’re getting an error or warning and you haven’t noticed it in the console window

To help gain more insight into your problem, I recommend liberally sprinkling Debug.Log() statements through your code to display information in realtime.

Doing this should help you answer these types of questions:

  • is this code even running? which parts are running? how often does it run? what order does it run in?
  • what are the names of the GameObjects or Components involved?
  • what are the values of the variables involved? Are they initialized? Are the values reasonable?
  • are you meeting ALL the requirements to receive callbacks such as triggers / colliders (review the documentation)

Knowing this information will help you reason about the behavior you are seeing.

You can also supply a second argument to Debug.Log() and when you click the message, it will highlight the object in scene, such as Debug.Log("Problem!",this);

If your problem would benefit from in-scene or in-game visualization, Debug.DrawRay() or Debug.DrawLine() can help you visualize things like rays (used in raycasting) or distances.

You can also call Debug.Break() to pause the Editor when certain interesting pieces of code run, and then study the scene manually, looking for all the parts, where they are, what scripts are on them, etc.

You can also call GameObject.CreatePrimitive() to emplace debug-marker-ish objects in the scene at runtime.

You could also just display various important quantities in UI Text elements to watch them change as you play the game.

Visit Google for how to see console output from builds. If you are running a mobile device you can also view the console output. Google for how on your particular mobile target, such as this answer or iOS: How To - Capturing Device Logs on iOS or this answer for Android: How To - Capturing Device Logs on Android

If you are working in VR, it might be useful to make your on onscreen log output, or integrate one from the asset store, so you can see what is happening as you operate your software.

Another useful approach is to temporarily strip out everything besides what is necessary to prove your issue. This can simplify and isolate compounding effects of other items in your scene or prefab.

Here’s an example of putting in a laser-focused Debug.Log() and how that can save you a TON of time wallowing around speculating what might be going wrong:

“When in doubt, print it out!™” - Kurt Dekker (and many others)

Note: the print() function is an alias for Debug.Log() provided by the MonoBehaviour class.

3

Uhhh so I fixed it, I guess… Apparently there wasnt an issue. I closed unity and opened it again and the error was gone and all is working fine now. I have no idea why it thought it wasnt being initialised before, but it was :eyes::eyes::eyes::eyes::eyes: