c#中Equals方法和GetHashCode

    class Program
    {
        static void Main(string[] args)
        {
            var stu1 = new Student(1, "Zhangsan");
            var stu2 = new Student(2, "Lisi");
            var stu3 = new Student(1, "Zhangsan-rename");


            var dic = new Dictionary<Student, string>();
            dic[stu1] = "aaa";
            dic[stu2] = "bbb";
            dic[stu3] = "ccc";
        }
    }

    public class Student
    {
        public Student(int id, string name)
        {
            Id = id;
            Name = name;
        }

        public int Id { get; set; }
        public string Name { get; set; }

        public override bool Equals(object obj)
        {
            return obj is Student student && this.Id == student.Id;
        }

        public override int GetHashCode()
        {
            //return DateTime.Now.Millisecond;
            return this.Id;
        }
    }

        public override int GetHashCode()
        {
            return DateTime.Now.Millisecond;
            //return this.Id;
        }