NullReferenceException: Object reference not set to an instance of an object when calling transform.localScale

Question

I have a 2D array of gameObjects pieces. When I want to rescale them in my private void ScalePieces() method, I get a NullReferenceException. If I instead just use Debug.Log() I dont get an Error. This is the whole code:

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

public class PieceDrawer : MonoBehaviour
{
    public string[,] BoardArray = new string[8, 8];
    public GameObject[,] pieces = new GameObject[8, 8];

    private bool setup = false;
    public float scale = 0.7f;
    
    private (int, int) WhiteKing = (0, 0);
    private (int, int) BlackKing = (0, 0);

    public GameObject bishopBlack, bishopWhite, kingBlack, kingWhite, knightBlack, knightWhite;
    public GameObject pawnBlack, pawnWhite, queenBlack, queenWhite, rookBlack, rookWhite;

    private Dictionary<string, GameObject> PrefabPiece = new Dictionary<string, GameObject>();

    public string fen = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1";

    void Start()
    {
        PrefabPiece["b_b"] = bishopBlack;
        PrefabPiece["b_w"] = bishopWhite;
        PrefabPiece["k_b"] = kingBlack;
        PrefabPiece["k_w"] = kingWhite;
        PrefabPiece["n_b"] = knightBlack;
        PrefabPiece["n_w"] = knightWhite;
        PrefabPiece["p_b"] = pawnBlack;
        PrefabPiece["p_w"] = pawnWhite;
        PrefabPiece["q_b"] = queenBlack;
        PrefabPiece["q_w"] = queenWhite;
        PrefabPiece["r_b"] = rookBlack;
        PrefabPiece["r_w"] = rookWhite;

    }
    
    private void Update()
    {
        if (fen != "" && !setup)
        {
            SetupPieces();
            setup = true;
        }
    }
    
    private void SetupPieces()
    {
        var x = 0;
        var y = 0;

        var fenList = fen.Split();
        foreach (var position in fenList[0])
        {
            if (position == '/')
            {
                x = 0;
                y++;
            }
            else if (char.IsDigit(position))
            {
                for (int i = 0; i < (position - '0'); i++)
                {
                    BoardArray[x + i, y] = " ";
                }
                x += position - '0';
            }
            else
            {
                switch (position)
                {
                    case 'k':
                        BlackKing = (x, y);
                        break;
                    case 'K':
                        WhiteKing = (x, y);
                        break;
                }
                var clr = char.IsUpper(position) ? "_w" : "_b";
                BoardArray[x, y] = position.ToString().ToLower() + clr;
                x++;
            }
        }

        DrawPieces();
    }

    private void DrawPieces()
    {
        for (int x = 0; x < 8; x++) 
        {
            for (int y = 0; y < 8; y++) 
            {
                if (BoardArray[x, y] != " ")
                {
                    pieces[x, y] = Instantiate (PrefabPiece[BoardArray[x, y]], new Vector3 (x, y, 0), Quaternion.identity);
                    pieces[x, y].GetComponent<SpriteRenderer>().sortingOrder = 1;
                    ScalePieces();
                }
            }
        }
    }

    private void ScalePieces()
    {
        for (int x = 0; x < 8; x++)
        {
            for (int y = 0; y < 8; y++)
            {
                // Debug.Log("Hello");
                Vector3 scaleVec = new Vector3(scale, scale, 1);
                pieces[x, y].transform.localScale = scaleVec;
            }
        }
    }

}

And the error message I get in unity:

NullReferenceException: Object reference not set to an instance of an object
PieceDrawer.ScalePieces () (at Assets/PieceDrawer.cs:118)
PieceDrawer.DrawPieces () (at Assets/PieceDrawer.cs:104)
PieceDrawer.SetupPieces () (at Assets/PieceDrawer.cs:91)
PieceDrawer.Update () (at Assets/PieceDrawer.cs:44)

As I said changing the method to something else fixes the error, so I think it definetly has to do with transform.localScale. I also tried calling the method from other methods; same error.

Please point out the line that throws the exception. And what does "If I instead just use Debug.Log()" mean? Please be complete and specific. Note, AFAIK you should call `string.Split` with an argument. — JHBonarius, Feb 18 '21 at 13:04
Does this answer your question? [What is a NullReferenceException, and how do I fix it?](https://stackoverflow.com/questions/4660142/what-is-a-nullreferenceexception-and-how-do-i-fix-it) — SomeBody, Feb 18 '21 at 13:07
@JHBonarius I meant replacing the transforming code with just a debug message to the console as you can see in the last method (it is commented out for now). — Honn, Feb 18 '21 at 13:11
@SomeBody I looked into this before and couldn't figure out my problem, but with the answer from Henrik, i made some decent progress. — Honn, Feb 18 '21 at 13:23

score 2 · Accepted Answer · answered Feb 18 '21 at 13:10

2

ScalePieces is called inside the loop in DrawPieces when not all entries of pieces[] are set. Better call it after the loop.

answered Feb 18 '21 at 13:10

Henrik

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Thanks a lot! What an oversight. It fixed one of four errors, lets see if I can find the other three by myself with this new information :) – Honn Feb 18 '21 at 13:12

NullReferenceException: Object reference not set to an instance of an object when calling transform.localScale

1 Answers1