继承 System.Collections.CollectionBase 创建一个强类型集合类

using System;

namespace Joe_s_Doughnut_Shop_CSharp
{
    /**//// <summary>
    /// Summary description for DoughnutCollection.
    /// </summary>
    public class DoughnutCollection : System.Collections.CollectionBase
    {
        public DoughnutCollection()
        {
            //
            // TODO: Add constructor logic here
            //
        }
          //添加对象
        public void Add(DoughnutMachine.Doughnut aDoughnut)
        {
            List.Add(aDoughnut);
        }
          //索引器
        public DoughnutMachine.Doughnut this[int index]
        {
            get
            {
                return (DoughnutMachine.Doughnut)List[index];
            }
        }
        //移除对象
        public void Remove(DoughnutMachine.Doughnut aDoughnut)
        {
            if (List.Contains(aDoughnut) == true)
            {
                List.Remove(aDoughnut);
            }
        }
    }
}