.Net 委托 delegate 学习

 public class Student
    {
        public int Id { get; set; }

        public string Name { get; set; }

        public int ClassId { get; set; }

        public int Age { get; set; }
    }

    public static  class StudentManager
    {
        public static List<Student> students = new List<Student>()
        {
            new Student(){ Id=1,Name="张三",ClassId=1001,Age=15 },
            new Student(){ Id=2,Name="李四",ClassId=1001,Age=15 },
            new Student(){ Id=3,Name="王五",ClassId=1001,Age=15 },
            new Student(){ Id=4,Name="赵六",ClassId=1001,Age=15 },
            new Student(){ Id=5,Name="杨幂",ClassId=1001,Age=14 },
            new Student(){ Id=6,Name="范冰冰",ClassId=101,Age=14 },
            new Student(){ Id=7,Name="张学友",ClassId=1021,Age=14},
            new Student(){ Id=8,Name="张三1",ClassId=1021,Age=16 },
            new Student(){ Id=9,Name="张三2",ClassId=1001,Age=17 },
            new Student(){ Id=10,Name="张三3",ClassId=1001,Age=15 },
            new Student(){ Id=11,Name="张三4",ClassId=1001,Age=19 },
            new Student(){ Id=12,Name="张三5",ClassId=1001,Age=25 },
            new Student(){ Id=13,Name="张三6",ClassId=1003,Age=25 },
            new Student(){ Id=14,Name="张三7",ClassId=1003,Age=25 },
            new Student(){ Id=15,Name="张三8",ClassId=1003,Age=25 },
            new Student(){ Id=16,Name="张三9",ClassId=1003,Age=25 },
            new Student(){ Id=17,Name="张三0",ClassId=1003,Age=25 },
            new Student(){ Id=18,Name="张三11",ClassId=1003,Age=15 },
            new Student(){ Id=19,Name="张三a",ClassId=1011,Age=15 },
            new Student(){ Id=20,Name="张三b",ClassId=1011,Age=15 },
            new Student(){ Id=21,Name="张三c",ClassId=1011,Age=15 },
            new Student(){ Id=22,Name="张三d",ClassId=1011,Age=15 },
            new Student(){ Id=23,Name="张三e",ClassId=1011,Age=15 },
            new Student(){ Id=24,Name="张三f",ClassId=1011,Age=15 },
            new Student(){ Id=25,Name="张三g",ClassId=3001,Age=15 },
            new Student(){ Id=26,Name="张三h",ClassId=3001,Age=13 },
            new Student(){ Id=27,Name="张三i",ClassId=3001,Age=13 },
            new Student(){ Id=28,Name="张三j",ClassId=3001,Age=13 },
            new Student(){ Id=29,Name="张三k",ClassId=3001,Age=13 },
        };

        public static List<Student> FindStudents(Func<Student,bool> func)
        {
            List<Student> stus = new List<Student>();

            foreach (var item in students)
            {
                if (func(item))
                {
                    stus.Add(item);
                }
            }
            return stus;
        }
        

        /// <summary>
        /// 查找ClassId为3001的学生
        /// </summary>
        /// <param name="student">学生</param>
        /// <returns>是否为3001班级的学生</returns>
        public static bool GetClassId(Student student)
        {
            if (student.ClassId==3001)
            {
                return true;
            }

            return false;
            
        }
        /// <summary>
        /// 年龄大于20的学生
        /// </summary>
        /// <param name="student"></param>
        /// <returns></returns>
        public static bool GetBigAge(Student student)
        {
            if (student.Age>20)
            {
                return true;
            }
            return false;
        }
        /// <summary>
        /// 年龄大于15 并且ClassId为1021
        /// </summary>
        /// <param name="student"></param>
        /// <returns></returns>
        public static bool GetStuByClassIdAndAge(Student student)
        {
            if (student.Age > 15 && student.ClassId==1021)
            {
                return true;
            }
            return false;
        }

    }

//List<Student> stus = StudentManager.students;

            //Console.WriteLine("姓名---年龄---班级--编号");
            //foreach (var item in stus)
            //{
            //    Console.WriteLine(item.Name+"---"+item.Age+"---"+item.ClassId+"---"+item.Id);
            //}

            List<Student> stus1=  StudentManager.FindStudents(StudentManager.GetStuByClassIdAndAge);
           
            Console.WriteLine("姓名---年龄---班级--编号");
            foreach (var item in stus1)
            {
                Console.WriteLine(item.Name + "---" + item.Age + "---" + item.ClassId + "---" + item.Id);
            }