getPriceBetween(String start, String end, CRUDRepository crud, String type)
{
  // i transform string in Date
  //
  switch(type)
  {
   case "typical" : tab= ((ClassDAO)crud).getPriceBetween(startDate,endDate);
    break;
   //
   //and it's the same
  //for all the
   //other cases
  //
  }
  return tab;

 }