public void AddBook(string id)
 {
     if (_container.IsTitleOverlapped(id))
     {
         Viewer.Instance.DrawError(error_titleOverlapped);
     }
     else if (_container.IsStorgaeLimit())
     {
         Viewer.Instance.DrawError(error_bookShelf);
     }
     else
     {
         Book newBook = new Book(id);
         Viewer.Instance.DrawBook(newBook);
         _container.AddBook(newBook);
         BookLoader.SaveBookIdList(_container.GetBookIdList());
     }
 }
 public void RemoveBook(Book book)
 {
     _container.RemoveBook(book);
     BookLoader.SaveBookIdList(_container.GetBookIdList());
 }