public void refreshReservations() { ReservationsService reservationsService = new ReservationsService(); List <Reservation> reservations = reservationsService.getAll(); reservationsList.Items.Clear(); foreach (Reservation reservation in reservations) { ListViewItem item = new ListViewItem(reservation.Id.ToString()); item.SubItems.Add(reservation.customer.ToString()); item.SubItems.Add(reservation.book.ToString()); reservationsList.Items.Add(item); } }