How to Instantiate an Integer Array in an Array of Arrays?

Question

I tried to create an array of arrays in Unity in order to edit the values in the Inspector, as you can't simply edit a multidimensional array. I want to be able to input an X and Y value that will allow me to adjust the length and width of the arrays.

 [System.Serializable]
 [ExecuteInEditMode()]
 public class Row{
     public int[] column;
 }
 
 [System.Serializable]
 [ExecuteInEditMode()]
 public class Array2D{
     public Row[] rows;
 }
 
 [System.Serializable]
 [ExecuteInEditMode()]
 public class test : MonoBehaviour {
     
     public int x;
     public int y;
     
     public Array2D Tiles;
     public bool refresh = false;
     
     // Use this for initialization
     void Start () {
     }
     
     // Update is called once per frame
     void Update () {
             if(refresh==true){
             setRowCol(x,y);
         }
     }
     
     void setRowCol(int r,int h){
         
         if(r>0&&h>0){
         Tiles.rows = new Row[r];
         
             for(int i=0; i<r;i++){
             Tiles.rows[i].column = new int[h];
             }
         }
         if(r==0||h==0){
             Debug.Log("0 is not a valid value for X or Y");
         }
         refresh=false;
     }
 }

The code works fine for the most part; however, this one line:

             Tiles.rows[i].column = new int[h];

Does not work however much I try. Can someone please tell me what the issue is? The error I get is a NullReferenceException.

Answer 1

Answer by KellyThomas · Jan 30, 2014 at 05:50 PM

 Tiles.rows = new Row[r];

That line is assigning an array or Rows but not actually instantiating any instances of Row. At that point the array holds a set of null values. You then receive an error when you try to access a property of the null in Tiles.rows[0].

Instead you should assign a new Row instance for each position in the rows[] array, then you can access their properties:

          for(int i=0; i<r;i++){
              Tiles.rows[i] =  new Row();
              Tiles.rows[i].column = new int[h];
          }

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Paikerchu13 · Jan 30, 2014 at 06:30 PM 0

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Thank you, I can't believe I missed something as simple as that!

How to Instantiate an Integer Array in an Array of Arrays?

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