public class Student
    {
        public Student(int id)
        {
            this.Id = id;
        }
        public int Id
        {
            get { return Id; }
            set
            {
                if (value == 1)
                {
                    Console.WriteLine("hello world！");
                }
            }
        }
    }

Student student = new Student(1);

Console.ReadKey();