Unity的优化系列3 - 理解数组、列表和字典的详细

创建时间：2016-05-28 投稿人：浏览次数：163

孙广东 2016.5.24

集合的影响有哪些？

难道应该完全停止使用字典集合么？

总之，几毫秒的缓慢循环都会让玩家发疯！！！（集合都太慢了）其实在游戏开发中经常会遇到对集合数据的排序：

在应用程序中我们管理相关对象通过以下两种方式之一：

通过创建对象数组（创建就不变大小）
通过创建对象的集合（可以动态改变大小）

每一种集合都有特定的用途，都有自己的优点和缺点。

List<GameObject> myListOfGameObjects = new List<GameObject>();

Dictionary<int, String> myDictionary = new Dictionary<int, String>();

新建一个脚本作为测试：

public class GenericCollectionsTest : MonoBehaviour
{

    #region PUBLIC_DECLARATIONS

    public int numberOfIterations = 10000000;

    #endregion

    #region PRIVATE_DECLARATIONS

    private Stopwatch stopWatch;
  
    private List<int> intList;                 // 整数列表
    private Dictionary<int,int> intDictionary;    // 一本字典，键和值为整数。
    private int[] intArray;                     // 一个整数数组

    #endregion

    #region UNITY_CALLBACKS

    void Start()
    {
        stopWatch = new Stopwatch();
        intArray = new int[numberOfIterations];
        intList = new List<int>();
        intDictionary = new Dictionary<int, int>();

        AddFakeValuesInArray(numberOfIterations);
        AddFakeValuesInList(numberOfIterations);
        AddFakeValuesInDictionay(numberOfIterations);
    }

    void Update()
    {
        if (Input.GetKeyDown(KeyCode.Space))
        {
            PerformTest();
        }

        if (Input.GetKeyDown(KeyCode.S))
        {
            SearchInList(111);
            SearchInDictionary(numberOfIterations - 1);
            UnityEngine.Debug.Log("SearchComplete");
        }
    }

    #endregion

    #region PRIVATE_METHODS

    private void AddFakeValuesInArray(int iterations)
    {
        for (int i = 0; i < iterations; i++)
        {
            intArray[i] = Random.Range(0, 100);
        }
    }

    private void AddFakeValuesInList(int iterations)
    {
        for (int i = 0; i < iterations; i++)
        {
            intList.Add(Random.Range(0, 100));
        }
        intList[iterations - 1] = 111;
    }


    private void AddFakeValuesInDictionay(int iterations)
    {
        for (int i = 0; i < iterations; i++)
        {
            intDictionary.Add(i, Random.Range(0, 100));
        }
        intDictionary[iterations - 1] = 111;
    }

    private void SearchInList(int value)
    {
        #region FIND_IN_LIST
        stopWatch.Start();
        int index = intList.FindIndex(item => item == value);

        stopWatch.Stop();
        UnityEngine.Debug.Log("Index " + index);
        UnityEngine.Debug.Log(“Time Taken to Find in List  ”+stopWatch.ElapsedMilliseconds+” ms”);
        stopWatch.Reset();
        #endregion

        #region CHECK_IF_CONTAINS_VALUE_IN_LIST
        stopWatch.Start();
        bool containsValue = intList.Contains(value);

        stopWatch.Stop();
        UnityEngine.Debug.Log(containsValue);
        UnityEngine.Debug.Log(“Time Taken To Check in List ”+stopWatch.ElapsedMilliseconds+” ms”);
        stopWatch.Reset();
        #endregion
    }

    private void SearchInDictionary(int key)
    {
        #region FIND_IN_DICTIONARY_USING_REQUIRED_KEY
        stopWatch.Start();
        int value = intDictionary[key];
        stopWatch.Stop();
        UnityEngine.Debug.Log((“Time Taken to Find in Dictionary   ”+stopWatch.ElapsedMilliseconds+” ms”);
        stopWatch.Reset();
        #endregion

        #region CHECK_IF_DICTIONARY_CONTAINS_VALUE
        stopWatch.Start();
        bool containsKey = intDictionary.ContainsKey(key);

        stopWatch.Stop();
        UnityEngine.Debug.Log(containsKey);
        UnityEngine.Debug.Log("Time taken to check if it contains key in Dictionary" + stopWatch.ElapsedMilliseconds+ “ ms”);
        stopWatch.Reset();
        #endregion
    }

    private void PerformTest()
    {
        
        #region ARRAY_ITERATION        // 循环遍历数组
        stopWatch.Start();

        for (int i = 0; i < intArray.Length; i++)
        {

        }

        stopWatch.Stop();
        UnityEngine.Debug.Log(“Time Taken By Array ”+stopWatch.ElapsedMilliseconds+ ”ms”);
        stopWatch.Reset();

        #endregion

        #region LIST_ITERATION            //  循环遍历列表中使用简单的 for 循环
        stopWatch.Start();
        for (int i = 0; i < intList.Count; i++)
        {

        }
        stopWatch.Stop();
        UnityEngine.Debug.Log(“Time Taken By List ”+stopWatch.ElapsedMilliseconds+ ”ms”);
        stopWatch.Reset();
        #endregion

        #region LIST_ITERATION_BY_FOREACH_LOOP             //  遍历列表中通过使用 foreach 循环
        stopWatch.Start();
        foreach (var item in intList)
        {
            
        }
        stopWatch.Stop();
        UnityEngine.Debug.Log(“Time Taken By List Using foreach  ”+stopWatch.ElapsedMilliseconds+ ”ms”);
        stopWatch.Reset();
        #endregion

        #region DICTIONARY_ITERATIOn_LOOP                //  遍历字典
        stopWatch.Start();

        foreach (var key in intDictionary.Keys)
        {

        }
        stopWatch.Stop();
        UnityEngine.Debug.Log(“Time Taken By Dictionary ”+stopWatch.ElapsedMilliseconds+ ”ms”);
        stopWatch.Reset();
        #endregion
    }
    #endregion
}

关于秒表类Stopwatch ，用于测试函数的执行时间特别方便。请参阅以下链接︰ http://www.dotnetperls.com/stopwatch （注意这个类是官方的API）

运行之后的输出如下：