public class Product    {        public int Id { get; set; }        // 自增ID        public string Name { get; set; }        // 名称        public string Code { get; set; }        // 主键        public string Category { get; set; }        // 类型        public decimal Price { get; set; }        // 价格        public DateTime ProduceDate { get; set; }        //产品时间        /// <summary>        /// 重写ToString 方法        /// </summary>        /// <returns></returns>        public override string ToString()        {            return String.Format("{0}{1}{2}{3}{4}{5}",            this.Id.ToString().PadLeft(2), this.Category.PadLeft(15),            this.Code.PadLeft(7), this.Name.PadLeft(17), this.Price.ToString().PadLeft(8),            this.ProduceDate.ToString("yyyy-M-d").PadLeft(13));        }        public static ProductCollection GetSampleCollection()        {            ProductCollection collection = new ProductCollection(                    new Product { Id = 1, Code = "1001", Category = "Red Wine", Name = "Torres Coronas", Price = 285.5m, ProduceDate = DateTime.Parse("1997-12-8") },                    new Product { Id = 3, Code = "2001", Category = "White Spirit", Name = "Mao Tai", Price = 1680m, ProduceDate = DateTime.Parse("2001-5-8") },                    new Product { Id = 4, Code = "2013", Category = "White Spirit", Name = "Wu Liang Ye", Price = 1260m, ProduceDate = DateTime.Parse("2005-8-1") },                    new Product { Id = 8, Code = "3001", Category = "Beer", Name = "TSINGTAO", Price = 6.5m, ProduceDate = DateTime.Parse("2012-4-21") },                    new Product { Id = 11, Code = "1003", Category = "Red Wine", Name = "Borie Noaillan", Price = 468m, ProduceDate = DateTime.Parse("1995-7-6") },                    new Product { Id = 15, Code = "1007", Category = "Red Wine", Name = "Pinot Noir Rose", Price = 710m, ProduceDate = DateTime.Parse("1988-9-10") },                    new Product { Id = 17, Code = "3009", Category = "Beer", Name = "Kingway", Price = 5.5m, ProduceDate = DateTime.Parse("2012-6-13") }            );            return collection;        }    }

public class ProductCollection    {        public Hashtable table;         public ProductCollection()        {            table = new Hashtable();        }        public ProductCollection(params Product[] array)        {//初始化            table = new Hashtable();            foreach (Product item in array)            {                this.Add(item);            }        }        public ICollection Keys { get { return table.Keys; } }        /// <summary>        /// 根据索引获取当前Key值        /// </summary>        /// <param name="index">索引</param>        /// <returns></returns>        public string GetKeys(int index)        {            if (index < 0 || index > table.Keys.Count)                throw new Exception("超出索引范围");            string selectN = "";            int i = 0;            foreach (string item in table.Keys)            {                if (index == i)                {                    selectN = item; break;                }                i++;            }            return selectN;        }        public Product this[int index]        {            get            {                string key = GetKeys(index);                return table[key] as Product;            }            set { string key = GetKeys(index); table[key] = value; }        }        /// <summary>        /// 根据Key值获得对应内容        /// </summary>        /// <param name="Name"></param>        /// <returns></returns>        public string GetKeys(string Name)        {            foreach (string item in table.Keys)            {                if (item==Name)                {                    return item;                }            }            throw new Exception("不存在此键值");        }        public Product this[string Name]        {            get            {                string selects = GetKeys(Name);                return table[selects] as Product;            }            set            {                string key = GetKeys(Name);                table.Remove(table[key]);                this.Add(value);            }        }        /// <summary>        /// 添加功能        /// </summary>        /// <param name="item">添加类</param>        public void Add(Product item)        {            foreach (string key in table.Keys)            {                if(key==item.Code)                    throw new Exception("产品代码不能重复");            }             table.Add(item.Code,item);        }               /// <summary>        /// 移除功能        /// </summary>        /// <param name="item">添加类</param>        public bool Remove(Product item)        {            try            {                table.Remove(item.Code);                return true;            }            catch             {                return false;            }                 }         /// <summary>        /// 移除指定索引项        /// </summary>        /// <param name="index"></param>        /// <returns></returns>        public bool Remove(int index)        {            if (index < 0 || index > table.Count)                throw new Exception("超出索引范围");            string key = GetKeys(index);            table.Remove(key);            return true;         }        /// <summary>        /// 清除所有内容        /// </summary>        public void clear()        {            table = new Hashtable();        }        /// <summary>        /// 获取总数        /// </summary>        public int Count { get { return table.Keys.Count; } }    }