博客
关于我
强烈建议你试试无所不能的chatGPT，快点击我
最全数据结构详述: List VS IEnumerable VS IQueryable VS ICollection VS IDictionary
阅读量：7225 次
发布时间：2019-06-29

本文共 17391 字，大约阅读时间需要 57 分钟。

本文对常用的数据结构详述：Array, ArrayList，List，IList，ICollection, Stack, Queue, HashTable, Dictionary, IQueryable, IEnumerable。

Complete Collection Comparison

 

Collection（集合）

Collection是数据记录集合，

编写代码过程中，常常需要合适的容器保存临时数据，方便修改和查找，如何选取合适的数据容器，关键在于将执行的数据操作以及数据记录是否大量。

Array（数组）

特征

1. 固定大小，数组的大小是初始化时决定无法修改的数值。

2. 强类型，存储数据元素类型必须在初始化时指定，因此在运行时，不需要耗费额外的时间来定义数组类型，能够大大提升运行效率。

3. 可使用Foreach关键字实现数组迭代和查找。

因为数组大小是固定的，且是强类型数据结构，因此在运行时只占用很少的内存，运行时效率很高。

1:  //It is obvious that strArray is
2:        //1. string   --> Strongly Type
3:        //2. Sized=10 --> Fixed Size
4:   
5:        string[] strArray = new string[10];
6:   
7:        for (int i = 0; i < 10; i++)
8:        {
9:            if (strArray[i]==null)
10:            {
11:                strArray[i] = (i+1).ToString();
12:            }
13:        }
14:   
15:        this.ListBoxArray.DataSource = null;
16:        this.ListBoxArray.Items.Clear();
17:   
18:        this.ListBoxArray.DataSource = strArray;
19:        this.ListBoxArray.DataBind();

ArrayList

1. ArrayList 没有固定的长度，容量可动态增加，可应用于开发人员无法确定数组元素个数等场景，当然这种情况下，在定义结构体的时候会非常耗时。

2. ArrayList 不是强类型，ArrayList中不同元素类型可以不相同，并且需要在运行时根据实际的输入来确定元素类型。因此在运行时消耗内存较多。

3. 可使用Froeach 关键字操作ArrayList。

1:  public class Product
2:      {
3:          public Product()
4:          {
5:
6:          }
7:          public Product(string Code, string Name)
8:          {
9:              _Code = Code;
10:              _Name = Name;
11:          }
12:   
13:              public string _Code {get; set;}
14:              public string _Name { get; set; }
15:      }

ArrayList支持String,int,以及十进制小数类型。

1:  //It is NOT obvious that strArrayList is 1. string? int? object? decimal?  --> NOT Strongly Type
2:   //                                       2. Sized=10? 20? 100?             -->NOT Fixed Size
3:   // Namespace: System.Collections
4:   
5:   System.Collections.ArrayList strArrayList = new System.Collections.ArrayList();
6:   //System.Linq.IQueryable  type of data is not specific runtime defered support
7:   strArrayList.Add("Mahsa");  //   "Mahsa": is string
8:   strArrayList.Add(1);        //        1 : is integer
9:   strArrayList.Add(0.89);     //      0.89: is decimal
10:   
11:   this.ListBoxArrayList.DataSource = null;
12:   this.ListBoxArrayList.Items.Clear();
13:   this.ListBoxArrayList.DataSource = strArrayList;
14:   this.ListBoxArrayList.DataBind();
15:   
16:   System.Text.StringBuilder str= new System.Text.StringBuilder();
17:   
18:   foreach (var item in strArrayList)
19:   {
20:       str.Append(" , "+item);
21:   }
22:   this.lblArrayList.Text = str.ToString();
23:   
24:   //Below is old way to fill obj from product , in Arraylist you need to create more than one instance
25:  // Product objProduct = new Product();
26:  // objProduct.Code = "1001";
27:  // objProduct.Name = "Chair";
28:   
29:   //It is NOT obvious that strArrayList is
30:   //1. string? int? object? decimal? OR OBJECT??  --> NOT Strongly Type
31:   //2. Sized=10? 20? 100?                         -->NOT Fixed Size
32:   // Namespace: System.Collections
33:   
34:   System.Collections.ArrayList objArrayList = new System.Collections.ArrayList();
35:   
36:   objArrayList.Add(new Product("1001", "Chair"));
37:   objArrayList.Add(new Product("1002", "Sofa"));
38:   objArrayList.Add(new Product("1003", "Carpet"));
39:   
40:   this.DropDownListArrayListObject.DataSource = null;
41:   this.DropDownListArrayListObject.Items.Clear();
42:   this.DropDownListArrayListObject.DataSource = objArrayList;
43:   
44:   //* Finding among Object of Array List is difficult , you have to find your specific item by index
45:   Product objTemp = (Product)objArrayList[0];
46:   objArrayList.Remove(objTemp);
47:   //*
48:   this.DropDownListArrayListObject.DataTextField = "_Name";
49:   this.DropDownListArrayListObject.DataValueField = "_Code";
50:   this.DropDownListArrayListObject.DataBind();
51:   this.GridViewArrayListObject.DataSource = objArrayList;
52:   this.GridViewArrayListObject.DataBind();

HashTable（哈希表）

HashTable是一种定义关键字的数据结构体，使用哈希表查找数据非常方便，哈希表既不是强类型也不固定大小限制。

1:  //It is NOT obvious that strArrayList is
2:         //1. string? int? object? decimal? OR OBJECT??  --> NOT Strongly Type
3:         //2. Sized=10? 20? 100?                         -->NOT Fixed Size
4:         // Namespace: System.Collections
5:         //Hashtable solve the problem in Arraylist when we are looking for specific item
6:         //Hashtable dedicate a key for each item, then finding item is easier and faster
7:   
8:          System.Collections.Hashtable objHashTable = new System.Collections.Hashtable();
9:   
10:          objHashTable.Add("1001","Chair");
11:          objHashTable.Add("1002", "Sofa");
12:          objHashTable.Add("1003", "Carpet");
13:   
14:   
15:         this.DropDownListHashTable.DataSource = null;
16:         this.DropDownListHashTable.Items.Clear();
17:         this.DropDownListHashTable.DataSource = objHashTable;
18:         //* finding item is easier you just need to point to it by call its key
19:         objHashTable.Remove("1002");
20:         //*
21:         this.DropDownListHashTable.DataTextField = "Value";
22:         this.DropDownListHashTable.DataValueField = "Key";
23:         this.DropDownListHashTable.DataBind();

Stack

栈是最典型的数据结构，栈具有优先级划分的数据结构，栈为每个内容项定义优先级，表示每个Item入栈和出栈的优先顺序。因此操作栈中的数据，需要先将数据push 到栈的顶部，需要删除元素必须变成栈顶部，即要遵守后进先出（LIFO）的原则。

栈与哈希表一样既不是强类型也不限制元素个数。

Push 操作

1:  //Stack is LIFO: Last in First Out
2:         System.Collections.Stack objStackPush = new System.Collections.Stack();
3:   
4:         //By Push method you can insert item at the top of the stack
5:         objStackPush.Push("Mahsa");
6:         objStackPush.Push("Hassankashi");
7:         this.lblPop.Text = "";
8:         this.ListBoxStack.DataSource = objStackPush.ToArray();
9:         this.ListBoxStack.DataBind();

Pop操作

1:  System.Collections.Stack objStackPop = new System.Collections.Stack();
2:   
3:  objStackPop.Push("Mahsa");
4:  objStackPop.Push("Hassankashi");
5:   
6:  //By Pop method you can remove item from the top of the stack --> Last in First in
7:  this.lblPop.Text = objStackPop.Pop().ToString();
8:   
9:  this.ListBoxStack.DataSource = objStackPop.ToArray();
10:  this.ListBoxStack.DataBind();

Queue

Queue同栈一样也是具有优先级定义的结构体，遵循的规则是先进先出（FIFO），既不是强类型也不具有固定的大小限制。

 

入队操作

1:  //Queue is FIFO: First in First Out
2:  System.Collections.Queue objQueue = new System.Collections.Queue();
3:   
4:  //By Enqueue method you can insert item at the END of the Queue
5:  objQueue.Enqueue("Mahsa");
6:  objQueue.Enqueue("Hassankashi");
7:  objQueue.Enqueue("Cosmic");
8:  objQueue.Enqueue("Verse");
9:   
10:  this.lblQueue.Text = "";
11:  this.ListBoxQueue.DataSource = objQueue.ToArray();
12:  this.ListBoxQueue.DataBind();
 
出队操作 
 
1:  System.Collections.Queue objQueue = new System.Collections.Queue();
2:   
3:  objQueue.Enqueue("Mahsa");
4:  objQueue.Enqueue("Hassankashi");
5:  objQueue.Enqueue("Cosmic");
6:  objQueue.Enqueue("Verse");
7:   
8:  //By Dequeue method you can remove item from the BEGINING of the Queue --> First in First out FIFO
9:  this.lblQueue.Text=objQueue.Dequeue().ToString();
10:   
11:  this.ListBoxQueue.DataSource = objQueue.ToArray();
12:  this.ListBoxQueue.DataBind();

入队操作

1:  System.Collections.Queue objQueue = new System.Collections.Queue();
2:   
3:  objQueue.Enqueue("Mahsa");
4:  objQueue.Enqueue("Hassankashi");
5:  objQueue.Enqueue("Cosmic");
6:  objQueue.Enqueue("Verse");
7:   
8:  //By Dequeue method you can remove item from the BEGINING of the Queue --> First in First out FIFO
9:  this.lblQueue.Text=objQueue.Dequeue().ToString();
10:   
11:  this.ListBoxQueue.DataSource = objQueue.ToArray();
12:  this.ListBoxQueue.DataBind();

List

什么情况下需要使用List？

1. List长度可不固定

2. 当数据为通用类型，List是强类型，List中元素类型不需要等到运行时来确定，这种特性使得List 运行时效率非常高。

3. 可使用Foreach关键字。

因为List不需要设定固定的大小，List灵活度高，且效率高常用于开发过程中。

1:  //Like Array is Strong Type
2:  //Like ArrayList with No Dimension
3:  System.Collections.Generic.List
     
       strList = new List
      
       ();
      
     
4:   
5:   
6:  strList.Add("Mahsa");
7:  strList.Add("Hassankashi");
8:  strList.Add("Cosmic");
9:  strList.Add("Verse");
10:   
11:  this.ListBoxListGeneric.DataSource = strList;
12:  this.ListBoxListGeneric.DataBind();
13:   
14:  System.Text.StringBuilder str = new System.Text.StringBuilder();
15:   
16:  foreach (var item in strList)
17:  {
18:      str.Append(" , " + item);
19:  }
20:  this.lblList.Text = str.ToString();

IList

IList 继承了List，包含多种方法的List接口。如果你无法判断代码改动的可能性，可以使用IList接口，减少模块之间的依赖性。IList是接口因此无法被实例化，所以必须使用List来初始化。

1:  System.Collections.Generic.IList
     
       strIList = new List
      
       ();

我们一起了解一下具体的类和接口之间的区别。

1. 具体类可继承其他类，并实现一个或多个接口。

2. 在内部类中可以定义变量并赋值，接口中不允许此操作。

3. 具体类可包含构造函数，而接口中不能定义构造函数

4. 抽象类中可包含访问修饰符如public,private等，接口中不能包含。

 

 

1:  //Ilist can not be instantiate from Ilist , so it should be instantiate from List
2:  System.Collections.Generic.IList
     
       strIList = new List
      
       ();
      
     
3:   
4:  strIList.Add("Mahsa");
5:  strIList.Add("Hassankashi");
6:  strIList.Add("Cosmic");
7:  strIList.Add("Verse");
8:   
9:   
10:  this.ListBoxListGeneric.DataSource = strIList;
11:  this.ListBoxListGeneric.DataBind();
12:   
13:  System.Text.StringBuilder str = new System.Text.StringBuilder();
14:   
15:  foreach (var item in strIList)
16:  {
17:      str.Append(" , " + item);
18:  }
19:  this.lblList.Text = str.ToString();

IEnumerable

IEnumerable常用于遍历集合元素，但是无法修改（删除或添加）数据，使用IEnumberable 会从服务器端将所有数据拷贝到客户端，并进行一定的过滤，如果服务器端有大量数据会造成内存负载超重。

 

1:  //IEnumerable can not be instantiate from Enumerable , so it should be instantiate from List
2:         System.Collections.Generic.IEnumerable
     
       empIEnumerable = new List
      
     
3:         {   new Employee { ID = 1001, Name="Mahsa"},
4:             new Employee { ID = 1002, Name = "Hassankashi" },
5:             new Employee { ID = 1003, Name = "CosmicVerse" },
6:             new Employee { ID = 1004, Name = "Technical" }
7:         };
8:   
9:   
10:         this.GridViewIEnumerable.DataSource = empIEnumerable;
11:         this.GridViewIEnumerable.DataBind();
12:   
13:         System.Text.StringBuilder str = new System.Text.StringBuilder();
14:   
15:         foreach (Employee item in empIEnumerable)
16:         {
17:             str.Append(" , " + item.ID +"-"+item.Name);
18:         }
19:   
20:         this.lblIEnumerable.Text = str.ToString();

IQueryable

IQueryable与IEnumberable不同的是，当从服务器端加载过量的数据，IQueryable会自动减少应用负载。IQueryable可保证大数据量时应用程序的高性能。

IQueryable会先过滤数据，然后发送给客户端。

1:  DataAccessEntities ctx = new DataAccessEntities();
2:          var ctx = new DataAccessEntities();

1:  //Difference between IQueryable and IEnumerable
2:   
3:          //You can instantiate IEnumerable from List
4:   
5:          IEnumerable
     
       queryIEnumerable = new List
      
       () ;
      
     
6:   
7:   
8:          //Bring  ALL records from server --> to client then filter collection
9:         //To bring all data from server you should omit where cluse from linq to sql
10:          queryIEnumerable = from m in ctx.Employees select m;
11:   
12:          //If you use where as extension method with IEnumerable then All records will be loaded
13:          queryIEnumerable = queryIEnumerable.Where(x => x.ID == 1).ToList();
14:
15:   
16:   
17:          //You can not instantiate IQueryable
18:   
19:          IQueryable
     
       queryIQueryable=null;
     
20:   
21:          //Bring just ONE record from server --> to client
22:   
23:          queryIQueryable = (from m in ctx.Employees
24:                       where m.ID == 1
25:                       select m);
26:   
27:          //Whenever you call IQueryable so ==> It will be executed
28:          this.GridViewIQueryable.DataSource = queryIQueryable.ToList();
29:          this.GridViewIQueryable.DataBind();
30:

SQL Profiler:

如何追踪查询语句生成TSQL，生成需要的数据结构体：

Step 1:

Start -> MS SQL Server 2008 -> Performance Tools -> SQL Server Profiler

Step 2:

SQL Server Profiler -> File -> New Trace

Step 3:

输入连接数据库的用户名和密码

Step 4:

General (Tab) -> Use the Template: Standard

Step 5:

Event Selection (Tab) -> Event : TSQL -> Select : SQL-BatchCompleted | Select Show all Columns

Press Column Filter -> Database Name: Like: "DataAccess"

运行

Step 6:

查看结果

Step 7:
生成 IEnumerable数据 :

 

1:  SELECT
2:  [Extent1].[ID] AS [ID],
3:  [Extent1].[Name] AS [Name],
4:  [Extent1].[Age] AS [Age]
5:  FROM [dbo].[Employee] AS [Extent1]

生成 IQueryable :

 

SELECT [Extent1].[ID] AS [ID], [Extent1].[Name] AS [Name], [Extent1].[Age] AS [Age]FROM [dbo].[Employee] AS [Extent1]WHERE 1 = [Extent1].[ID]

 

ICollection 继承了IEnumberable，但是IEnumberable是基于索引的，ICollection不基于索引。

1:  //IList {indexer and Modify} vs ICollection {randomly and Modify}
2:   //Collection can not be instantiate from ICollection , so it should be instantiate from List
3:   System.Collections.Generic.ICollection
     
       strICollection = new List
      
       ();
      
     
4:   strICollection.Add("Mahsa");
5:   strICollection.Add("Hassankashi");
6:   
7:   //Countable***
8:   int ICollectionCount=strICollection.Count;
9:   
10:   this.ListBoxICollection.DataSource = strICollection;
11:   this.ListBoxICollection.DataBind();
12:   System.Text.StringBuilder str = new System.Text.StringBuilder();
13:   foreach (var item in strICollection)
14:   {
15:       str.Append(" , " + item);
16:   }
17:   this.lblICollection.Text = str.ToString();
18:   
19:   //IList***
20:   System.Collections.Generic.IList
     
       objIList = new List
      
       ();
      
     
21:   objIList = (from m in ctx.Employees
22:               select m).ToList();
23:   
24:  Employee obj = objIList.Where(i => i.Name == "Sara").FirstOrDefault();
25:  int indexofSara= objIList.IndexOf(obj);
26:  int cIList = objIList.Count;
27:   
28:   //ICollection***
29:   System.Collections.Generic.ICollection
     
       objICollection = new List
      
       ();
      
     
30:   objICollection = (from m in ctx.Employees
31:                     select m).ToList();
32:   Employee objIC = objICollection.Where(i => i.Name == "Sara").FirstOrDefault();
33:   //You can not get index of object , if you clear comment from below code appears error
34:  // int indexofSaraICollection = objIC.IndexOf(objIC);
35:   int cICollection = objICollection.Count;

Stack Generic

入栈：

1:  //Stack is LIFO: Last in First Out
2:         //Here is for Push Stack in Generic
3:         //System.Collections.Stack objStackPush = new System.Collections.Stack();
4:         //Stack
     
       can be instantiated from Stack
      
     
5:   
6:         System.Collections.Generic.Stack
     
       objStackPush = new System.Collections.Generic.Stack
      
       ();
      
     
7:   
8:         objStackPush.Push(1);
9:         objStackPush.Push(2);
10:   
11:         this.lblPopGeneric.Text = "";
12:         this.ListBoxStackGeneric.DataSource = objStackPush.ToArray();
13:         this.ListBoxStackGeneric.DataBind();

出栈：

1:  //Stack is LIFO: Last in First Out
2:         //Here is for Pop Stack in Generic
3:         //System.Collections.Stack objStackPop = new System.Collections.Stack();
4:         //Stack
     
       can be instantiated from Stack
      
     
5:   
6:         System.Collections.Generic.Stack
     
       objStackPop = new System.Collections.Generic.Stack
      
       ();
      
     
7:   
8:         objStackPop.Push(1);
9:         objStackPop.Push(2);
10:   
11:         this.lblPop.Text = objStackPop.Pop().ToString();
12:         this.ListBoxStack.DataSource = objStackPop.ToArray();
13:         this.ListBoxStack.DataBind();

Queue Generic

入队：

1:  //Queue is FIFO: First in First Out
2:         //Here is for Enqueue Queue in Generic
3:         //System.Collections.Queue objQueue = new System.Collections.Queue();
4:         //Queue
     
       can be instantiated from Queue
      
     
5:   
6:         System.Collections.Generic.Queue
     
       objQueue = new System.Collections.Generic.Queue
      
       ();
      
     
7:         objQueue.Enqueue(1);
8:         objQueue.Enqueue(2);
9:   
10:         this.lblQueue.Text = "";
11:   
12:         this.ListBoxQueue.DataSource = objQueue.ToArray();
13:         this.ListBoxQueue.DataBind();

出队：

1:  //Queue is FIFO: First in First Out
2:         //Here is for Enqueue Queue in Generic
3:         //System.Collections.Queue objQueue = new System.Collections.Queue();
4:         //Queue
     
       can be instantiated from Queue
      
     
5:   
6:         System.Collections.Generic.Queue
     
       objQueue = new System.Collections.Generic.Queue
      
       ();
      
     
7:         objQueue.Enqueue(1);
8:         objQueue.Enqueue(2);
9:   
10:         this.lblQueue.Text = "";
11:   
12:         this.ListBoxQueue.DataSource = objQueue.ToArray();
13:         this.ListBoxQueue.DataBind();

Dictionary 及 IDictionary：

Dictionary 可通用，而哈希表不是通用的。Dictionary定义 <TKey，Tvalue>。IDictionary是Dictionary的接口，如果在后期开发中需要大量修改，建议使用IDictionary。

//Dictionary can instantiate from Dictionary , Dictionary is similar to Hashtable,//Dictionary is GENERIC but Hashtable is NON GENERIC//Such Hashtable you can find object by its keySystem.Collections.Generic.Dictionary
    
      objDictionary = new Dictionary
     
      ();objDictionary.Add(1001, "Mahsa");objDictionary.Add(1002, "Hassankashi");objDictionary.Add(1003, "Cosmicverse");string str = objDictionary[1002];this.ListBoxDictionary.DataSource = objDictionary;this.ListBoxDictionary.DataBind();

转载地址：http://fzufm.baihongyu.com/

你可能感兴趣的文章
MFC限制edit控件的字符输入长度
查看>>
url rewrite优化url的可读性
查看>>
winform 窗体实现增删改查(CRUD)共用模式
查看>>
Yii查看执行的SQL
查看>>
poj_2709 贪心算法
查看>>
【程序员眼中的统计学（11）】卡方分布的应用
查看>>
【转】static_cast和reinterpret_cast
查看>>
Linux常用网络命令
查看>>
文件夹工具类 - FolderUtils
查看>>
Java中的集合框架
查看>>
后台dubug有值且sql也打印出来执行了但是前台就是查不到数据
查看>>
最近5年183个Java面试问题列表及答案［最全］
查看>>
机器学习(Machine Learning)&深度学习(Deep Learning)资料
查看>>
Python输入函数 raw_input( ) 与 input()
查看>>
Xwiki平台Windows搭建(Tomcat7 + XWiki6.2 + MySQL5.5)
查看>>
SSL/TLS握手过程
查看>>
WPF实现滚动显示的TextBlock
查看>>
如何使用Windows Library文件进行持久化
查看>>
【iCore组合式双核心开发板教程】【X-GUI教程】教程及代码包下载
查看>>
【JS】引用类型之Math
查看>>
喝酒易醉，品茶养心，人生如梦，品茶悟道，何以解忧？唯有杜康！-- 愿君每日到此一游！
当前时间: 2025-02-12 16:44:55   当前IP: 18.216.142.24   联系邮箱:javaeecc@qq.com     Copyright © 2020 - 2022 baihongyu.com 京ICP备2021015314号-2
强烈建议你试试无所不能的CHAT-GPT，快点击我
强烈建议你试试无所不能的CHAT-GPT，快点击我