简单工厂的核心 根据用户的输入创建对象赋值给父类

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;namespace _03简单工厂设计模式{    class Program    {        static void Main(string[] args)        {            Console.WriteLine("请输入您想要的笔记本品牌");            string brand = Console.ReadLine();            NoteBook nb = GetNoteBook(brand);            nb.SayHello();            Console.ReadKey();        }        /// <summary>        /// 简单工厂的核心 根据用户的输入创建对象赋值给父类        /// </summary>        /// <param name="brand"></param>        /// <returns></returns>        public static NoteBook GetNoteBook(string brand)        {            NoteBook nb = null;            switch (brand)            {                case "Lenovo": nb = new Lenovo();                    break;                case "IBM": nb = new IBM();                    break;                case "Acer": nb = new Acer();                    break;                case "Dell": nb = new Dell();                    break;            }            return nb;        }    }    public abstract class NoteBook    {        public abstract void SayHello();    }    public class Lenovo : NoteBook    {        public override void SayHello()        {            Console.WriteLine("我是联想笔记本，你联想也别想");        }    }    public class Acer : NoteBook    {        public override void SayHello()        {            Console.WriteLine("我是鸿基笔记本");        }    }    public class Dell : NoteBook    {        public override void SayHello()        {            Console.WriteLine("我是戴尔笔记本");        }    }    public class IBM : NoteBook    {        public override void SayHello()        {            Console.WriteLine("我是IBM笔记本");        }    }}