System.Collections.Generic.List.Add(zhuyuanxiaofei)

private void Button9_Click(object sender, RoutedEventArgs e)
        {
            List<zhuyuanxiaofei> xfs = new List<zhuyuanxiaofei>();
            string s = listView2.Items[listView2.SelectedIndex].ToString();
            string[] ss = s.Split(',');
            foreach (ListViewItem item in listView2.Items)
            {
                zhuyuanxiaofei xf = new zhuyuanxiaofei();
                xf.kId = int.Parse(txtId.Text);
                xf.yaoName = ss[0].Substring(4).Replace("=", "").Trim();
                xf.yaonum = int.Parse(ss[3].Substring(3).Replace("=", "").Trim());
                xfs.Add(xf);
                //MessageBox.Show(item.SubItems[3].Text);
            }
            new IdCard_BLL().p_zhuyuanxiaofei_insert(xfs);
        }

public List<zhuyuanxiaofei> p_zhuyuanxiaofei_select(int i)
        {
            SqlParameter kId = new SqlParameter("@kId", SqlDbType.Int);
            kId.Value = i;
            SqlParameter[] sp = { kId };
            SqlDataReader reader = DBHelper.SectionRoomSelect("p_zhuyuanxiaofei_select", sp);
            List<zhuyuanxiaofei> zhu = new List<zhuyuanxiaofei>();
            while (reader.Read())
            {
                zhuyuanxiaofei cd = new zhuyuanxiaofei();
                cd.kId = int.Parse(reader[1] + "");
                cd.yaoName = reader[2] + "";
                cd.yaonum = int.Parse(reader[3] + "");
                zhu.Add(cd);
            }
            DBHelper.con.Close();
            DBHelper.con.Dispose();
            DBHelper.cmd.Dispose();
            return zhu;

        }