public class DataClass
  {
    private List<User> userList = null; 

    public DataClass()
    {
      userList = new List<User>();
    }

    public DataClass( string savedList )
    {
      XmlSerializer serializer = new XmlSerializer( typeof(List<User>) );
      Object o;
      using (TextReader reader = new StringReader(savedList))
      {
        o = serializer.Deserialize(reader);
      }
      userList = (List<User>) o;
    }

    public List<User>  UserList
    {
      get { return userList;  }
      set { userList = value; }
    }
  }