消除随机重复？

Question

我有3个子类"Staff,Faculty,Student",每个类从父类人员那里得到用户的第一个姓氏,这个id就像在运行控制台应用程序时添加4个随机数.我遇到的问题是所有的类都得到相同的4位数,我该如何解决这个问题,是的,必须使用随机我不能使用静态计数器.

Person.cs"父类"

public class Person
    {
        static string title;
        protected string firstName;
        protected string lastName;
        protected string address;
        protected string gender;
        protected string dateOfBirth;
        protected string userID;
        protected Random rnd = new Random();

Faculty.cs

namespace Person
{
    public class Faculty : Person
    {
        public Faculty(string aTitle, string aFirstName, string aLastName, string aAddress,
           string aGender, string aDateOfBirth)
            : base(aTitle, aFirstName, aLastName, aAddress,
                    aGender, aDateOfBirth)
        {


            this.userID = firstName.Substring(0, 1) + lastName.Substring(0, 5);

            this.userID = this.userID + rnd.Next(1000, 9999);

            Console.WriteLine(this.userID);
        }


    }
}

Staff.cs

namespace Person
{
    public class Staff : Person
    {
        public Staff(string aTitle, string aFirstName, string aLastName, string aAddress,
           string aGender, string aDateOfBirth)
            : base(aTitle, aFirstName, aLastName, aAddress,
                    aGender, aDateOfBirth)
        {

            this.userID = firstName.Substring(0, 1) + lastName.Substring(0, 5);

            this.userID = this.userID + rnd.Next(1000, 9999);

            Console.WriteLine(userID);
        }


    }
}

测试类

   public class PersonTest
    {
       static void Main(string[] args) 
      {
          Person testPerson = new Faculty(" Mr.", "Merry ", "Lanes", " 493 Bluebane RD", "Male", " 8-06-1953\n ");


          Person studentPerson = new Student(" Mr.", "Jerry ", "Panes", " 456 Greenbane RD", "Male", " 8-10-1945\n");


          Person staffPerson = new Staff(" Mr.", "Joe ", "Gaines", " 495 Redbane RD", "Male", " 8-21-1989\n ");


            Console.ReadLine();
        }//end main

Answer 1

我没有看到你在哪里声明和初始化rnd.我猜测它在Person中声明为实例成员,并在Person的构造函数中初始化 - 始终默认初始化,这意味着它使用时间作为种子,这意味着所有使用毫秒的调用都获得相同的种子.

创建rnd一个静态成员,并在静态ctonstructor中初始化它一次.

更新:这应该是所需要的:

static readonly protected Random rnd = new Random();

(它也会更快,因为你只创建一个新的Random对象,而不是每个对象创建一次.从时钟创建种子相当慢.)