private int getPosition(int itemId, int userId, boolean ar) {
				int sizeVector = items_.size();
				ScheduleItem item;
				for (int i = 0; i < sizeVector; i++) {
					item = items_.get(i);
					if (item.getID() == itemId 
							&& item.getSenderID() == userId
							&& item.isAdvanceReservation() == ar)
						return i;
				}
				return -1;
			}