using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.UI;using System.Web.UI.WebControls;using System.Linq;using System.Collections.ObjectModel;using System.Collections;

namespace ListMethodTest{

public class TestItem    {public int number { get; set; }public string str { get; set; }

//used for SelectMany        public List<string> children { get; set; }

public override int GetHashCode()        {return number;        }    }

public class InnerClass    {public int id { get; set; }public string name { get; set; }    }

public class ChildTestItem : TestItem    { }

public class ConvertTest    {public int a { get; set; }    }

public partial class _Default : System.Web.UI.Page    {        List<TestItem> lst1 = new List<TestItem>();protected void Page_Load(object sender, EventArgs e)        {

            lst1.Add(new TestItem() { number = 3, str = "dsdfsf", children = new List<string>() { "c1", "c2" } });            lst1.Add(new TestItem() { number = 1, str = "csdfsdf", children = new List<string>() { "c3", "c4" } });            lst1.Add(new TestItem() { number = 2, str = "aasdfsdf" });            lst1.Add(new TestItem() { number = 2, str = "222" });

int part = 3;switch (part)            {case 1: Part1();break;case 2: Part2(); break;case 3: Part3(); break;default: break;            }        }

private void Part3()        {int sum = lst1.Sum(x => x.number);            List<TestItem> take = lst1.Take(3).ToList();

//同样 take前面的             List<TestItem> takewhile = lst1.TakeWhile(x => x.number == 3).ToList();

//key必须唯一// Dictionary<int,TestItem> toDic=   lst1.ToDictionary(x => x.number);

//Ilookup:IEnumerable<TElement> this[TKey key] { get; }   所以可以有重key            ILookup<int, TestItem> lookup = lst1.ToLookup(x => x.number);

//lst1.TrimExcess();

bool trueforall = lst1.TrueForAll(x => x.number > -1);

            List<TestItem> where = lst1.Where(x => x.number == 2).ToList();

        }

void Part2()        {// 里面的 item和原来的是一个引用，即便 不重写GetHashCode            List<TestItem> getR = lst1.GetRange(1, 2);

            IEnumerable<IGrouping<int, TestItem>> gb = lst1.GroupBy(x => x.number);

int io = lst1.IndexOf(lst1[1]);

            lst1.Insert(0, new TestItem() { number = 0, str = "00" });

            List<TestItem> toInsert = new List<TestItem>()            {new TestItem() { number = 0, str = "InsertRange0"},new TestItem() { number = 2, str = "InsertRange1" },new TestItem() { number = 9, str = "InsertRange2" },            };//lst1.InsertRange(0, toInsert);

//返回 lst1中与  toInsert 相等的 元素             List<TestItem> Intersect = lst1.Intersect(toInsert, new DistinctTest()).ToList();

            List<InnerClass> inner = new List<InnerClass>() { 

new InnerClass(){ id=1, name="name1"},new InnerClass(){ id=2, name="name2"},new InnerClass(){ id=3, name="name3"},

            };

// 2个list的 TKEY 类型必须一致， 返回 key相等的组合 ，其实就是 key相等的 inner join// 最后一个委托只是根据组合 生成 返回的结果            IEnumerable join = lst1.Join(inner, x => x.number, i => i.id, (a, b) => new { a.number, a.str, b.id, b.name });

// 类似  dictionary,    lst1为key, 匹配的 InnerClass 的集合为value ，即使集合count为0(没有匹配) ,也会组合            IEnumerable gj = lst1.GroupJoin(inner, x => x.number, i => i.id, (a, b) => new { id = a.number, name = a.str, lst = b });

            IEnumerable zip = lst1.Zip(inner, (x, y) => new { x.number, x.str, y.id, y.name });

            TestItem last = lst1.Last(x => x.number == 2);

int lindex = lst1.LastIndexOf(lst1[2]);

int max = lst1.Max(x => x.number);int min = lst1.Min(x => x.number);

//lst1.Add(new ChildTestItem());//IEnumerable<ChildTestItem>   ot=  lst1.OfType<ChildTestItem>();

            List<TestItem> ob = lst1.OrderBy(x => x.str).ToList();

//lst1.Sort((a, b) => {//        if( a.number< b.number)  return -1;//        else if( a.number == b.number) return 0;//        else return 1;//    } );

// TestItem temp =lst1[0];// bool remove = lst1.Remove(temp);

// int  ra=    lst1.RemoveAll(x => x.number == 2);

// lst1.RemoveAt(2);

//lst1.RemoveRange(2, 2);

//lst1.Reverse();

// select 是变形用的 ，这个词太唬人了，别被他的外表所蒙蔽            IEnumerable select = lst1.Select(x => new { id = x.number, name = x.str, g = Guid.NewGuid() });            IEnumerable select1 = lst1.Select((x, y) => new { id = x.number, name = x.str, index = y, g = Guid.NewGuid() });//flatten            IEnumerable SelectMany = lst1.SelectMany(x => x.children == null ? new List<string>() : x.children);

            List<TestItem> s1 = new List<TestItem>()           {new TestItem(){  number=1 ,str="sdf" }           };

            List<TestItem> s2 = new List<TestItem>()           {new TestItem(){  number=1  }           };

//个数不一样肯定 false            bool se = s1.SequenceEqual(s2, new DistinctTest());

            List<TestItem> union = s1.Union(s2).ToList();

//不single的话 throw exception//TestItem singe = lst1.Single(x => x.number ==2);

            List<TestItem> skip = lst1.Skip(2).ToList();//注意 bypass   前面的element            List<TestItem> SkipWhile = lst1.SkipWhile(x => x.number == 0).ToList();

        }

void Part1()        {//  ( (item 1,2 的结果 )  和item 3的结果)和item 4的结果            TestItem agg = lst1.Aggregate((i, j) => { i.number += j.number; return i; });

bool all = lst1.All(i => i.str.Contains("c"));

bool any = lst1.Any(i => i.str.Contains("c"));

            ParallelQuery p = lst1.AsParallel();

            IQueryable<TestItem> q = lst1.AsQueryable();

var query = from ti in q where ti.number == 2 select ti;

            ReadOnlyCollection<TestItem> readonlylst = lst1.AsReadOnly();

double average = lst1.Average(i => i.number);

int index = lst1.BinarySearch(new TestItem() { number = 1, str = "123123" }, new CompareClass());

//如果lst1是非泛型的集合 ，转换之后就可以用泛型的方法啦！ where, any ,select , all等            IEnumerable<TestItem> castedLst = lst1.Cast<TestItem>();

            List<TestItem> lsttoConcat = new List<TestItem>() { new TestItem() { number = 4 } };            List<TestItem> concatedLst = lst1.Concat(lsttoConcat).ToList();

            TestItem t = new TestItem() { number = 4 };            lst1.Add(t);//bool contains = lst1.Contains<TestItem>(t);            bool contains = lst1.Contains<TestItem>(new TestItem() { number = 4 });//bool contains = lst1.Contains<string>("sdfsdf");   it's wrong!

            List<ConvertTest> convertedLst = lst1.ConvertAll(i => new ConvertTest() { a = i.number });

            TestItem[] arr = new TestItem[10];            lst1.CopyTo(arr, 3);

//下面defLst count 为 0            IEnumerable<TestItem> defLst = lst1.DefaultIfEmpty();

            IEnumerable<TestItem> dsicLst = lst1.Distinct();

            lst1.Add(new TestItem() { number = 4, str = "sdfsd" });            IEnumerable<TestItem> dsicLst1 = lst1.Distinct<TestItem>(new DistinctTest());

            TestItem elementat = lst1.ElementAt(1);            TestItem elementatORDefault = lst1.ElementAtOrDefault(10);

            List<TestItem> toexcept = new List<TestItem>()            {                lst1[2],                lst1[3]

            };

            IEnumerable<TestItem> exceptedLst = lst1.Except(toexcept);

bool exist = lst1.Exists(i => i.number == 4);

            TestItem find = lst1.Find(i => i.number == 4);

            List<TestItem> findall = lst1.FindAll(i => i.number == 4);

int fIndex = lst1.FindIndex(i => i.number == 4);

            TestItem fLast = lst1.FindLast(i => i.number == 4);

int lastIndex = lst1.FindLastIndex(i => i.number == 4);

            TestItem first = lst1.First(x => x.number == 4);

            lst1.ForEach(x => x.str = x.number == 4 ? "4" : x.str);        }

    }

public class DistinctTest : IEqualityComparer<TestItem>    {public bool Equals(TestItem x, TestItem y)        {if (x.number == y.number) return true;else return false;        }

public int GetHashCode(TestItem obj)        {//HashCode默认情况就是地址的散列码，跟散列算法有关系,所以默认情况不同对象的hashcode是不一样的，所以要重写TestItem的GetHashCode方法。//用最简单的方法来说，hashcode就是一个签名。当两个对象的hashcode一样时，两个对象就"有可能"一样。如果不一样的话两个对象就"肯定"不一样。            return obj.GetHashCode();        }    }

public class CompareClass : IComparer<TestItem>    {public int Compare(TestItem x, TestItem y)        {if (x.number < y.number) return -1;else if (x.number == y.number) return 0;else return 1;        }    }}

转载自：http://www.cnblogs.com/wangtian52127/archive/2012/03/30/2425482.html