Adding to a List inside a Coroutine doesn't add properly?

Question

Hey everyone, I have a piece of code that can be simplified to t$$anonymous$$s:

 private List<List<int>> tempListListInt = new List<List<int>>();
     private List<int> tempListInt = new List<int>();
 
 void Start()
     {
         StartCoroutine(TestListListInt());
     }
 
 IEnumerator TestListListInt()
     {
         int tempInt;
         for (int i = 0; i < 10; i++)
         {
             tempListInt.Clear();
             yield return null;
             for (int j = 0; j < 10; j++)
             {
                 tempInt = Random.Range(0, 10);
                 tempListInt.Add(tempInt);
             }
             tempListListInt.Add(tempListInt);
         }
     }

when reading tempListListInt each List < int > stored inside is a copy of a List < int > tempListInt generated for i=9. I suppose I screwed somet$$anonymous$$ng up with accessing global tempListListInt, but I am at loss as to what exactly. Help, pretty please?

Answer 1

Best Answer

Answer by TBruce · Sep 28, 2016 at 08:06 PM

Instead of List<List<int>> try using a class, like t$$anonymous$$s

 using UnityEngine;
 using System.Collections;
 using System.Collections.Generic;
 
 [System.Serializable]
 public class IntList
 {
     public List<int> list = new List<int>();
 }
  
 public class  : MonoBehaviour
 {
     private List<IntList> tempListListInt = new List<IntList>();
     private IntList tempListInt = new IntList();
 
     void Start()
     {
         StartCoroutine(TestListListInt());
     }
 
     IEnumerator TestListListInt()
     {
         int tempInt;
         int total = 0;
         tempListListInt.Clear();
         for (int i = 0; i < 10; i++)
         {
             tempListInt.Clear();
             yield return null;
             for (int j = 0; j < 10; j++)
             {
                 tempInt = Random.Range(0, 10);
                 total += tempInt;
                 tempListInt.list.Add(tempInt);
             }
             tempListListInt.Add(tempListInt);
         }
         yield return null;
         ShowListTotal(total);
     }
 
     // shows the total calculated in coroutine
     // and total from list
     void ShowListTotal(int total)
     {
         int tempTotal = 0;
         for (i = 0; i < tempListListInt.Count; i++)
         {
             for (j = 0; j < tempListListInt[i].list.Count; j++)
             {
                 tempTotal += tempListListInt[i].list[j];
             }
         }
         Debug.Log("Coroutine total equals " + total + ", list total equals " + tempTotal);
     }
 }

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Ankhe · Sep 28, 2016 at 09:24 PM 0

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Thank you for the reply, but it didn't work. Still, every tempListListInt entry is the same :(

TBruce Ankhe · Sep 28, 2016 at 10:38 PM 1

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I did not test my original code. The problem was the reuse of the following private property

 private IntList tempListInt = new IntList();

This is the reason why each iteration of tempListListInt was always the same (they always stored the last value). Way was required was to replace this

 tempListInt.Clear();

with this

 IntList tempListInt = new IntList();

so that when adding to the tempListListInt each value would be unique. See the updated script below

 using UnityEngine;
 using System.Collections;
 using System.Collections.Generic;
 
 [System.Serializable]
 public class IntList
 {
     public List<int> list = new List<int>();
 }
  
 public class TestTempList : MonoBehaviour
 {
     private List<IntList> tempListListInt = new List<IntList>();
 
     void Start()
     {
         Calculate();
     }
     
     IEnumerator TestListListInt()
     {
         int tempInt;
         int total = 0;
         tempListListInt.Clear();
         for (int i = 0; i < 10; i++)
         {
             IntList tempListInt = new IntList();
             yield return null;
             for (int j = 0; j < 10; j++)
             {
                 tempInt = Random.Range(0, 10);
                 total += tempInt;
                 tempListInt.list.Add(tempInt);
             }
             tempListListInt.Add(tempListInt);
         }
         yield return null;
         ShowListTotal(total);
     }
 
     // shows the total calculated in coroutine
     // and total from list
     void ShowListTotal(int total)
     {
         int tempTotal = 0;
         for (int i = 0; i < tempListListInt.Count; i++)
         {
             for (int j = 0; j < tempListListInt[i].list.Count; j++)
             {
                 tempTotal += tempListListInt[i].list[j];
             }
         }
         Debug.Log("Coroutine total equals " + total + ", list total equals " + tempTotal);
     }
 
     public void Calculate()
     {
         StartCoroutine(TestListListInt());
     }
 }

TBruce Ankhe · Sep 29, 2016 at 02:17 AM 0

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@Ankhe Have you had any success with this? Here is a link to a Unity package that tests the functionality of the list.

The demo has a button so that allows continual test as well as a text field to show results.

Ankhe TBruce · Sep 29, 2016 at 04:36 PM 0

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Just checked it, it works! Thank you very much. Lovely.

Adding to a List inside a Coroutine doesn't add properly?

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