C#中List的排序(Sort)

要对自定义类数组或List进行排序，譬如：

List<User> userList;

ArrayList arrayList;

最重要的是：继承IComparer<T>接口，实现int IComparer<T>.Compare(T t1, T t2)方法。

代码如下：




/// <summary>


/// 继承IComparer<T>接口，实现同一自定义类型　对象比较


/// </summary>


/// <typeparam name="T">T为泛用类型</typeparam>


public class Reverser<T> : IComparer<T>


{


private Type type = null;


private ReverserInfo info;




/// <summary>


/// 构造函数


/// </summary>


/// <param name="type">进行比较的类类型</param>


/// <param name="name">进行比较对象的属性名称</param>


/// <param name="direction">比较方向(升序/降序)</param>


public Reverser(Type type, string name, ReverserInfo.Direction direction)


{


this.type = type;


this.info.name = name;


if (direction != ReverserInfo.Direction.ASC)


this.info.direction = direction;


}




/// <summary>


/// 构造函数


/// </summary>


/// <param name="className">进行比较的类名称</param>


/// <param name="name">进行比较对象的属性名称</param>


/// <param name="direction">比较方向(升序/降序)</param>


public Reverser(string className, string name, ReverserInfo.Direction direction) {


try


{


this.type = Type.GetType(className, true);


this.info.name = name;


this.info.direction = direction;


}


catch (Exception e){


throw new Exception(e.Message);


}


}




/// <summary>


/// 构造函数


/// </summary>


/// <param name="t">进行比较的类型的实例</param>


/// <param name="name">进行比较对象的属性名称</param>


/// <param name="direction">比较方向(升序/降序)</param>


public Reverser(T t, string name, ReverserInfo.Direction direction)


{


this.type = t.GetType();


this.info.name = name;


this.info.direction = direction;


}




//必须！实现IComparer<T>的比较方法。


int IComparer<T>.Compare(T t1, T t2)


{


object x = this.type.InvokeMember(this.info.name, BindingFlags.Public | BindingFlags.Instance | BindingFlags.GetProperty, null, t1, null);


object y = this.type.InvokeMember(this.info.name, BindingFlags.Public | BindingFlags.Instance | BindingFlags.GetProperty, null, t2, null);


if (this.info.direction != ReverserInfo.Direction.ASC)


Swap(ref x, ref y);


return (new CaseInsensitiveComparer()).Compare(x, y);


}




//交换操作数


private void Swap(ref object x, ref object y)


{


object temp = null;


temp = x;


x = y;


y = temp;


}


}




/// <summary>


/// 对象比较时使用的信息类


/// </summary>


public struct ReverserInfo


{


/// <summary>


/// 比较的方向，如下：


/// ASC：升序


/// DESC：降序


/// </summary>


public enum Direction


{


ASC = 0,


DESC,


};




public enum Target


{


CUSTOMER = 0,


FORM,


FIELD,


SERVER,


};




public string name;


public Direction direction;


public Target target;


}



上面主要是运用了 C#的反射 和 Framework中的排序算法。

像上面那样实现接口后，就可以使用List<T>进行 升序/降序 排序了。

测试代码如下：




using System;


using System.Collections.Generic;


using System.Collections;


using System.Reflection;


using System.Text;




namespace List_T_SortTest_u_2


{


#region 测试Reverser<T>代码段




/// <summary>


/// 实体类User，测试用


/// </summary>


public class User


{


protected string _name;


protected int _age;


protected string _address;




public User(string name, int age, string address)


{


this._name = name;


this._age = age;


this._address = address;


}




public string Name


{


get { return _name; }


set { _name = value; }


}




public int Age


{


get { return _age; }


set { _age = value; }


}




public string Address


{


get { return _address; }


set { _address = value; }


}


}




/// <summary>


/// 主程序类(启动类)，测试用


/// </summary>


class Program


{


static void Main(string[] args)


{


List<User> userList = new List<User>();


User user;




user = new User("Wang", 21, "ShenYang");


userList.Add(user);


user = new User("Yan", 27, "JinZhou");


userList.Add(user);


user = new User("Liu", 26, "BeiJing");


userList.Add(user);


user = new User("Zhao", 30, "ChaoYang");


userList.Add(user);


user = new User("Yang", 27, "FuXin");


userList.Add(user);




//for (int i = 0; i < ar.Count; i++ )


// ;


Console.Write("Name ");


Console.Write("Age ");


Console.Write("Address " + " " + " ");


Console.WriteLine("-----------------------");


foreach (User u in userList)


{


Console.Write(u.Name + " ");


Console.Write(u.Age + " ");


Console.Write(u.Address + " " + " ");


}


Console.WriteLine();




Reverser<User> reverser = new Reverser<User>(user.GetType(), "Name", ReverserInfo.Direction.DESC);


userList.Sort(reverser);


Console.WriteLine();


foreach (User u in userList)


{


Console.Write(u.Name + " ");


Console.Write(u.Age + " ");


Console.Write(u.Address + " " + " ");


}


Console.WriteLine();




reverser = new Reverser<User>(user.GetType(), "Age", ReverserInfo.Direction.ASC);


userList.Sort(reverser);


Console.WriteLine();


foreach (User u in userList)


{


Console.Write(u.Name + " ");


Console.Write(u.Age + " ");


Console.Write(u.Address + " " + " ");


}




Console.Read();


}


}


#endregion




}