List 的内容在 start() 和 update() 之间丢失答案

【问题标题】：Content of List gets Lost between start() and update()List 的内容在 start() 和 update() 之间丢失
【发布时间】：2020-07-03 09:29:03
【问题描述】：

我尝试使用来自 tilemap 的图块创建一个列表，并使用该列表获取 tilemap 上的图块坐标。我想通过查看更新函数中的 cmets 问题很明显，但我不知道该怎么办

public class Spawner : MonoBehaviour
{
    private GameObject[] getCount;
    private int count;
    public int maxBags = 1;
    public Transform goldBag;
    public List<int> possibleTiles;
    public int possibleTilesLength;
    private int randomTileNr;
    public List<int> copyOfPossibleTiles;

    void Start()
    {
        Tilemap tilemap = GetComponent<Tilemap>();
        BoundsInt bounds = tilemap.cellBounds;
        TileBase[] allTiles = tilemap.GetTilesBlock(bounds);
        List<int> possibleTiles = new List<int>();
        for (int x = 0; x < bounds.size.x; x++) {
            for (int y = 0; y < bounds.size.y; y++) {
                TileBase tile = allTiles[x + y * bounds.size.x];
                if (tile != null) {
                    possibleTiles.Add(x);
                    Debug.Log(possibleTiles.Count);
                    possibleTiles.Add(y);
                    Debug.Log(possibleTiles.Count);
                    possibleTilesLength = possibleTiles.Count;
                }
            }
        }
    }
    void Update()
    {
        getCount = GameObject.FindGameObjectsWithTag("bagCoins");
        if(getCount.Length < maxBags)
        {
            randomTileNr = (int)UnityEngine.Random.Range(0,possibleTilesLength/2)*2;
            Debug.Log(possibleTiles.Count);                 //prints 0
            Debug.Log(possibleTilesLength);                 //prints 128
            Debug.Log(randomTileNr);                        //prints random even number between 0 and 128
            Debug.Log(copyOfPossibleTiles[randomTileNr]);   //prints error index out of range.
            maxBags = 0;
Instantiate(goldBag, new Vector3(possibleTiles[randomTileNr],possibleTiles[randomTileNr+1],0), Quaternion.identity);
        }
    }
}

【问题讨论】：

欢迎来到变量作用域的主题

标签： c# list unity3d indexing

【解决方案1】：

您将它们存储在Start中的局部变量中

List<int> possibleTiles = new List<int>();
for (int x = 0; x < bounds.size.x; x++) {
...

隐藏同名字段。因此，您在Start 中所做的更改不会更改您的Update 方法尝试访问的全局已知列表possibleTiles。

宁可使用您已有的字段并正确初始化它

public List<int> possibleTiles = new List<int>();

在Start 中只做

possibleTiles.Clear();
for (int x = 0; x < bounds.size.x; x++) {
...

【讨论】：

【解决方案2】：

给你，这可能就是你想要的

public class Spawner : MonoBehaviour
{
    private GameObject[] getCount;
    private int count;
    public int maxBags = 1;
    public Transform goldBag;
    public List<int> possibleTiles = new List<int>(); // Initialized list holding possible tiles
    public int possibleTilesLength;
    private int randomTileNr;
    public List<int> copyOfPossibleTiles;

    void Start()
    {
        Tilemap tilemap = GetComponent<Tilemap>();
        BoundsInt bounds = tilemap.cellBounds;
        TileBase[] allTiles = tilemap.GetTilesBlock(bounds);
        // Remove the line below since we want to declare the list as member variable and we already initialized it
        //List<int> possibleTiles = new List<int>();
        
        possibleTiles.Clear();
        for (int x = 0; x < bounds.size.x; x++) {
            for (int y = 0; y < bounds.size.y; y++) {
                TileBase tile = allTiles[x + y * bounds.size.x];
                if (tile != null) {
                    possibleTiles.Add(x);
                    Debug.Log(possibleTiles.Count);
                    possibleTiles.Add(y);
                    Debug.Log(possibleTiles.Count);
                    possibleTilesLength = possibleTiles.Count;
                }
            }
        }
    }
    void Update()
    {
        getCount = GameObject.FindGameObjectsWithTag("bagCoins");
        if(getCount.Length < maxBags)
        {
            randomTileNr = (int)UnityEngine.Random.Range(0,possibleTilesLength/2)*2;
            Debug.Log(possibleTiles.Count);                 //prints 0
            Debug.Log(possibleTilesLength);                 //prints 128
            Debug.Log(randomTileNr);                        //prints random even number between 0 and 128
            Debug.Log(copyOfPossibleTiles[randomTileNr]);   //prints error index out of range.
            maxBags = 0;
Instantiate(goldBag, new Vector3(possibleTiles[randomTileNr],possibleTiles[randomTileNr+1],0), Quaternion.identity);
        }
    }
}

【讨论】：