class Entity { public int ID{ get; set; } }interface ISortBehavor { int SortNumber{ get; set; } }

而上移与下移我们使用一个泛型方法来接收参数，这样扩展性更好一些，开发人员只要把需要上下移的集合传到方法里，之后你的集合就可以被排序，当然这里面会进行各个元素的移动操作！

    class Extenstion    {        /// <summary>        /// Sortable the specified list, id and newSort.        /// </summary>        /// <param name=‘list‘>        /// List.        /// </param>        /// <param name=‘id‘>        /// Identifier.        /// </param>        /// <param name=‘newSort‘>        /// New sort.        /// </param>        /// <typeparam name=‘T‘>        /// The 1st type parameter.        /// </typeparam>        public static void Sortable<T> (List<T> list, int id, int newSort) where T:class        {            var old = list.Find (i => (i as Entity).ID == id);            if (old == null || (old as ISortBehavor).SortNumber == newSort)                return;            if ((old as  ISortBehavor).SortNumber > newSort) {                (old as ISortBehavor).SortNumber = newSort;                foreach (ISortBehavor item in    list.FindAll(i=>(i as Entity).ID!=id && (i as ISortBehavor).SortNumber>=newSort)) {                    item.SortNumber += 1;                }                        } else {                (old as ISortBehavor).SortNumber = newSort;                            foreach (ISortBehavor item in    list.FindAll(i=>(i as Entity).ID!=id && (i as ISortBehavor).SortNumber<=newSort)) {                    item.SortNumber -= 1;                }            }            list.ForEach (i => {                Console.WriteLine ((i as Entity).ID + "sort:" + (i as ISortBehavor).SortNumber);            }            );        }    }

我们测试一下程序，看一下神奇的结果

    class MainClass    {        public static void Main (string[] args)        {            List<Person> list = new List<Person> ();            list.Add (new Person {ID=1,Name="zzl",SortNumber=1});            list.Add (new Person {ID=2,Name="zzl2",SortNumber=2});            list.Add (new Person {ID=3,Name="zzl3",SortNumber=3});            Console.WriteLine ("Hello World!");            Extenstion.Sortable (list, 1, 2);            Extenstion.Sortable (list, 2, 3);        }    }