继承ArrayList

 

     public   class  Attachments : ArrayList
    {
         ///   <summary>
         ///  
         ///   </summary>
         public  Attachments()
        {
        }

         ///   <summary>
         ///  
         ///   </summary>
         ///   <param name="attachment"></param>
         ///   <returns></returns>
         public   int  Add(Attachment attachment)
        {    
             return   base .Add(attachment);
        }

         ///   <summary>
         ///  
         ///   </summary>
         public   new  Attachment  this [ int  nIndex] 
        { 
             get {  return  (Attachment) base [nIndex]; }

             set {  base [nIndex]  =  value; }
        }

    }

抄的