C# List 方法的使用

  class Collection
    {
        /// 

        /// 数据结构：数组
        /// 
        List list = new List();

       
        public static void Test()
        {
            Collection c = new Collection();
            c.listTest();
            Console.ReadKey();
        }

        private void InitList()
        {
            Student st1 = new Student("张三", 17, 1000);
            Student st2 = new Student("李四", 20, 1001);
            Student st3 = new Student("王五", 18, 1000);
            Student st4 = new Student("赵六", 19, 1001);
            Student st5 = new Student("钱七", 18, 1003);
            Student st6 = new Student("张九", 21, 1002);
            list.Add(st1);
            list.Add(st2);
            list.Add(st3);
            list.Add(st4);
            list.Add(st5);
            list.Add(st6);
        }

        public void listTest()
        {
            this.InitList();

            foreach (var item in list)
            {
                Console.WriteLine(item);
            }

           
            Console.WriteLine("\n*****根据Id分组*****");
            var query = list.GroupBy(pet => pet.Id);
            // IEnumerable> query = list.GroupBy((st) => { return st.Id; });
            // IEnumerable> query = list.GroupBy(ListGroud);         
            foreach (var item in query)
            {
                List stt = item.ToList();
                Console.WriteLine("key::" + item.Key);
                foreach (var item2 in stt)
                {
                    Console.WriteLine(item2);
                }
                Console.WriteLine("");
            }

            Console.WriteLine("\n获取元素在列表中的下标:" + list.BinarySearch(list[2]));
            Console.WriteLine("\n列表根据对象属性A,转换成属性A为key的字典对象（要保证建唯一）:");

            var dictionary2 = list.ToDictionary(st => st.Name);
            foreach (var item in dictionary2)
            {
                Console.WriteLine("key:" + item.Key + " ->value:" + item.Value);
            }
            Console.WriteLine("\n根据条件筛选:");
            var tempList = list.Where(a => a.Name.Contains("张") || a.Name.Contains("李")).ToList();
            // List tempList = list.FindAll(st => st.Name.Contains("张") || st.Name.Contains("李"));
            foreach (var item in tempList)
            {
                Console.WriteLine(item);
            }
            Console.WriteLine("\n计算列表中年龄总和：" + list.Sum(st => st.Age));

          ;

            list.Take(3); //获取列表前3项

            list.Skip(4); //截取（跳过前4条数据）

            var kk = list.GetRange(1, 3);  //从第1项起，获取后面三项，可以做分页。

            bool b = list.Exists(st => st.Name == "张三");  //判断是否存在某个属性

            var templist = list.OrderBy(st => st.Id);  //根据某个属性排序

            list.Sort();  //排序要求对象实现IComparable接口
            foreach (var item in templist)
            {
                Console.WriteLine(item);
            }
           int maxAge= list.Max(st => st.Age);
         Student ss=  list.Max();
        }

        private int ListGroud(Student st)
        {
            return st.Id;
        }


    }

    public class Student:IComparable
    {       
        public int Age;
        public int Id;
        public string Name;

        public Student(string name, int age, int Id)
        {
            this.Name = name;
            this.Age = age;
            this.Id = Id;
        }

        public override string ToString()
        {
            return string.Format("编号：{0}、姓名：{1}、年龄：{2}", this.Id, this.Name, this.Age);
        }

        public int CompareTo(object obj)
        {
            return this.Id > ((Student)obj).Id ? 1 : -1;
        }
    }