c# - 子列表项未在 C# 中显示

Question

我正在尝试在列表中添加一个列表。但我无法从子列表中检索项目。没有错误，但没有从子列表中检索到数据。请关注 GenerateClue() 我认为错误就在那里。

当我尝试使用 clueList[0][0] 访问数据时，没有数据

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

public class TrainingMode : MonoBehaviour {
    private List<int> answerKey;
    private List<int> clue;
    private List<List<int>> clueList;
    private int correct;
    private int wellPlaced;
    public Text answerKeyText;
    System.Random random = new System.Random();

    void Start () {
        answerKey = new List<int>();
        clue = new List<int>();
        clueList = new List<List<int>>();

        GenerateAnswerKey();
        GenerateClue();

        //CheckCorrectAndWellPlaced();

        answerKeyText.GetComponent<Text>().text = answerKey[0] + " "+ answerKey[1] + " "+ answerKey[2];
        foreach (List<int> arrClue in clueList)
        {
            foreach (int item in arrClue)
            {
                Debug.Log(item);
            }
        }
    }

    private void GenerateClue()
    {

        //Generate clue
        for (int j = 0; j <= 5; j++)
        {
            for (int i = 0; i <= 2; i++)
            {
                int randomNumber = random.Next(0, 9);
                if (clue.Contains(randomNumber))
                {
                    i--;
                }
                else
                {
                    clue.Add(randomNumber);
                }

                if (clue.Count == 3)
                {
                    clueList.Add(clue);
                    clue.Clear();
                }
            }
        }
    }

    private void CheckCorrectAndWellPlaced()
    {
        correct = 0;
        wellPlaced = 0;
        //Check for correct and wellplaced numbers
        for (int i = 0; i <= 2; i++)
        {
            if (answerKey.Contains(clue[i]))
            {
                correct++;
            }
            if (clue[i] == answerKey[i])
            {
                wellPlaced++;
            }
        }
    }

    private void GenerateAnswerKey() {
        //Generate answerkey
        for (int i = 0; i <= 2; i++)
        {
            int randomNumber = random.Next(0, 9);
            if (answerKey.Contains(randomNumber))
            {
                i--;
            }
            else
            {
                answerKey.Add(randomNumber);
            }
        }
    }
}

Answer 1

问题是，当您将线索添加到线索列表时，它实际做的是传递一个引用，因为 List<> 是一个类。所以你最终只有 2 个变量指向同一个内存。一个是线索变量，另一个是线索列表[X]。因此，当您调用 clue.Clear() 时，您正在清除与 clueList[X] 实际上相同的内存的线索列表。

作为修复，只是改变这个:

if (clue.Count == 3)
{
    clueList.Add(clue);
    clue.Clear();
}

进入这个:

if (clue.Count == 3)
{
    clueList.Add(new List<int>(clue));
    clue.Clear();
}