List集合排序Sort(Comparison<T> comparison)

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List< T > 集合对复杂类型的排序Sort()有4个重载
1.T类型实现了IComparable< T >接口
2.另写一个类，该类实现了IComparer< T >
3.Sort(Comparison< T > comparison),Comparison< T >为一个委托类型，CSDN定义如下：

public delegate int Comparison< T >（T x ,T y）;// 摘要:     //     表示比较同一类型的两个对象的方法。    //    // 参数:     //   x:    //     要比较的第一个对象。    //   y:    //     要比较的第二个对象。    // 类型参数:     //   T:    //     要比较的对象的类型。    // 返回结果:     //     一个有符号整数，指示 x 与 y 的相对值，如下表所示。 值 含义 小于 0 x 小于 y。 0 x 等于 y。 大于 0 x 大于 y。

实现第三种方法的实现有3种途径：

1.定义一个方法，定义一个委托实例，将该委托实例传入Sort()中eg. class Program    {        static void Main(string[] args)        {            Student sa1 = new Student(1, "Washington", 33);            Student sa2 = new Student(2, "Brown", 32);            Student sa3 = new Student(4, "Wade", 67);            Student sa4 = new Student(6, "Bosh", 47);            List <Student> list = new List<Student> (){sa1 ,sa2 ,sa3 ,sa4 };            Comparison<Student> comparison = new Comparison(SortByAge);//将方法传给委托实例            list.Sort(comparison);//将委托传入Sort()        }        //定义一个委托类型方法        static int SortByAge(Student x,Student y)        {            return x.Age.CompareTo(y.Age);        }    }    public class Student    {        public int ID { get; set; }        public string Name { get; set; }        public int Age { get; set; }        public string Type { get; set; }        public Student(int id, string name, int age)        {            this.ID = id;            this.Name = name;            this.Age = age;        }    }

2.使用匿名委托eg. class Program    {        static void Main(string[] args)        {            Student sa1 = new Student(1, "Washington", 33);            Student sa2 = new Student(2, "Brown", 32);            Student sa3 = new Student(4, "Wade", 67);            Student sa4 = new Student(6, "Bosh", 47);            List <Student> list = new List<Student> (){sa1 ,sa2 ,sa3 ,sa4 }; //匿名委托delegate(Student x, Student y){return x.Name.CompareTo(y.Name);}            list.Sort(delegate(Student x, Student y){return x.Name.CompareTo(y.Name);});        }        static int SortByAge(Student x,Student y)        {            return x.Age.CompareTo(y.Age);        }    }    public class Student    {        public int ID { get; set; }        public string Name { get; set; }        public int Age { get; set; }        public string Type { get; set; }        public Student(int id, string name, int age)        {            this.ID = id;            this.Name = name;            this.Age = age;        }    }

3.使用Lambda表达式eg. class Program    {        static void Main(string[] args)        {            Student sa1 = new Student(1, "Washington", 33);            Student sa2 = new Student(2, "Brown", 32);            Student sa3 = new Student(4, "Wade", 67);            Student sa4 = new Student(6, "Bosh", 47);            List <Student> list = new List<Student> (){sa1 ,sa2 ,sa3 ,sa4 };            //lambda表达式            list.Sort((x,y) => x.ID.CompareTo(y.ID));                foreach (Student s in listA )            {                Console.WriteLine(s.ID +" " + s.Name + " " + s.Age );            }         }    }    public class Student    {        public int ID { get; set; }        public string Name { get; set; }        public int Age { get; set; }        public string Type { get; set; }        public Student(int id, string name, int age)        {            this.ID = id;            this.Name = name;            this.Age = age;        }    }

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