Unity: Array of Lists variable. How to declare it correctly in C#-CodePudding

I need to declare an Array of Lists variable in Unity. Array size is fixed and it is 5. My code is working as i want, but i think there must be a better and a shorter way to do it:

public List<GameObject>[] charactersOnBoardSortedP1 = new List<GameObject>[] {new List<GameObject>(), new List<GameObject>(), new List<GameObject>(), new List<GameObject>(), new List<GameObject>() };

I tried to do like this:

public List<GameObject>[] charactersOnBoardSortedP1 = new List<GameObject>[5];

But i have an error: Object reference not set to an instance of an object.

Is there any way to declare my variable simpler? I mean if my array has only 5 slots it's ok, but what if 100? It's kind of stupid to copy new List... 100 times in declaration.

CodePudding user response：

try this. Test here

Create an Array of list variables. initialise each Array items to a new list of GameObject. then you can add to said array's list.

using System;
using System.Text;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
                    
public class Program
{
    public static void Main()
    {
        // create array of lists
        List<GameObject>[] COBSP1 = new List<GameObject>[5]; //charactersOnBoardSortedP1
        // setup lists
        COBSP1[0] = new List<GameObject>();
        COBSP1[1] = new List<GameObject>();
        COBSP1[2] = new List<GameObject>();
        COBSP1[3] = new List<GameObject>();
        COBSP1[4] = new List<GameObject>();
        
        // add objects to said list
        COBSP1[0].Add(new GameObject());
        COBSP1[0].Add(new GameObject());
        COBSP1[0].Add(new GameObject());
        COBSP1[0].Add(new GameObject());
        
        COBSP1[1].Add(new GameObject());
        COBSP1[1].Add(new GameObject());
        COBSP1[1].Add(new GameObject());
        COBSP1[1].Add(new GameObject());
        
        COBSP1[2].Add(new GameObject());
        COBSP1[2].Add(new GameObject());
        COBSP1[2].Add(new GameObject());
        COBSP1[2].Add(new GameObject());
        
        COBSP1[3].Add(new GameObject());
        COBSP1[3].Add(new GameObject());
        COBSP1[3].Add(new GameObject());
        COBSP1[3].Add(new GameObject());
        
        COBSP1[4].Add(new GameObject());
        COBSP1[4].Add(new GameObject());
        COBSP1[4].Add(new GameObject());
        COBSP1[4].Add(new GameObject());
    }
    
}

CodePudding user response：

try this

var  arraySize=6; //or what size you need

List<GameObject>[] charactersOnBoardSortedP1 = new List<GameObject>[arraySize];

charactersOnBoardSortedP1=  charactersOnBoardSortedP1
                           .Select(obsp => obsp = new List<GameObject>()) 
                            .ToArray();

or if you need to init some more things in the same time

for (var i=0; i<  charactersOnBoardSortedP1.Length; i  )
{
    charactersOnBoardSortedP1[i]=new List<GameObject>();
    // if you need to add some elements in the same time
    charactersOnBoardSortedP1[i].Add(new GameObject {Id=i});
}

CodePudding user response：

Easiest way to achieve it is as follows:

int arraySize = 5;
List<GameObject>[] charactersOnBoardSortedP1 = Enumerable.Repeat(new List<GameObject>(), arraySize).ToArray();

This will create array of specified size filled with empty List<GameObject>()

If you wish to have list to have GameObject you can modify above code a bit.

int arraySize = 5;
List<GameObject>[] charactersOnBoardSortedP1 = Enumerable.Repeat(new List<GameObject> { new GameObject()}, arraySize).ToArray();