@Override public String getMostPopularCarRentalCompany() { String popularCompany = ""; int nbReservations = 0; for (String companyString : this.getAllRentalCompanies()) { CarRentalCompany company = em.find(CarRentalCompany.class, companyString); int reservationCount = company.getTotalNbReservations(); if (reservationCount > nbReservations) { nbReservations = reservationCount; popularCompany = companyString; } } return popularCompany; }