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对于普通值类型（如int,string,double）的List来说，可以直接调用List<>.Sort()方法进行排序。如
List<int> intInList = new List<int>(); intInList.AddRange(new int[] { 1, 3, 2, 7, 5, 9, 8, 5, 6 }); intInList.Sort();
但是如果List中存储的是复杂类型(Complex type),那么就需要我们现实的实现排序算法。常用的有一下三种方式：
1）让需要排序的类实现IComparable<T>接口。如：现在有一个Person类，我们可以让Person类实现IComparable<Person>接口。这种方式让Person类有一个默认的排序算法。
public class Person : IComparable<Person> { public int ID { get; set; } public string FirstName { get; set; } public string LastName { get; set; } public int CompareTo(Person other) { return this.ID.CompareTo(other.ID); } public override string ToString() { return string.Format("ID = {0}, FirstName = {1}, LastName = {2}",this.ID,this.FirstName,this.LastName); } }
上面的代码演示了让Person类默认按照ID大小排序。
测试代码:
static void Main(string[] args) { List<int> intInList = new List<int>(); intInList.AddRange(new int[] { 1, 3, 2, 7, 5, 9, 8, 5, 6 }); intInList.Sort(); List<Person> personInList = new List<Person>(); personInList.AddRange(new Person[] { new Person() { ID=2, FirstName = "Robert", LastName = "Stack" }, new Person() { ID =1 , FirstName = "John", LastName = "Snow" }, new Person() { ID=3, FirstName="Aya", LastName="Stack" } }); PrintAllList(personInList); Console.WriteLine(new string(‘-‘, 40)); personInList.Sort(); PrintAllList(personInList); } public static void PrintAllList(List<Person> personInList) { foreach (Person person in personInList) { Console.WriteLine(person); } }
运行结果:
ID = 2, FirstName = Robert, LastName = Stack ID = 1, FirstName = John, LastName = Snow ID = 3, FirstName = Aya, LastName = Stack ---------------------------------------- ID = 1, FirstName = John, LastName = Snow ID = 2, FirstName = Robert, LastName = Stack ID = 3, FirstName = Aya, LastName = Stack Press any key to continue . . .
2)有的时候，我们并不能获取到Person类的源代码(如：我们正在使用一个别人写好的类库)，这个时候如果我们想对Person类实现排序，可以另外写一个专门的对Person进行排序的类，让该类实现IComparer<Person>接口,然后在List<Person>.Sort()方法中传入一个该类的实例即可。代码如下:
public class PersonComparer : IComparer<Person> { public int Compare(Person x, Person y) { return x.FirstName.CompareTo(y.FirstName); } }
上面的代码实现了对Person使用FirstName进行排序。
测试代码：
//省略相同代码.... PrintAllList(personInList); Console.WriteLine(new string(‘-‘, 40)); personInList.Sort(new PersonComparer()); PrintAllList(personInList);
运行结果：
ID = 2, FirstName = Robert, LastName = Stack ID = 1, FirstName = John, LastName = Snow ID = 3, FirstName = Aya, LastName = Stack ---------------------------------------- ID = 3, FirstName = Aya, LastName = Stack ID = 1, FirstName = John, LastName = Snow ID = 2, FirstName = Robert, LastName = Stack Press any key to continue . . .
3）上例通过创建一个类，然后实现IComparer接口的方式对Person指定排序算法。当List<>.Sort()在调用的时候，实际上在其内部是调用了IComparer的方法Compare（）。如果我们不想新建一个类，我们完全可以直接传一个代理函数到List<>.Sort()方法里面去，代码如下：
//省略相同代码.... PrintAllList(personInList); Console.WriteLine(new string(‘-‘, 40)); personInList.Sort((x, y) => { return x.LastName.CompareTo(y.LastName); }); PrintAllList(personInList);
上面的代码通过传入delegate 的方式实现了对Person类使用LastName进行排序的功能。
运行结果：
ID = 2, FirstName = Robert, LastName = Stack ID = 1, FirstName = John, LastName = Snow ID = 3, FirstName = Aya, LastName = Stack ---------------------------------------- ID = 1, FirstName = John, LastName = Snow ID = 3, FirstName = Aya, LastName = Stack ID = 2, FirstName = Robert, LastName = Stack Press any key to continue . . .
C#中List排序（Sort a list of complex types）
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原文地址：http://www.cnblogs.com/kuillldan/p/5057766.html
