public static void main(String[] args) { Tenant tenant = new Tenant(); Apartment apartment = new Apartment(); tenant.setApartment(apartment); List<Tenant> tenants = new ArrayList<Tenant>(); tenants.add(tenant); apartment.setTenants(tenants); Session session = HibernateUtil.getSessionFactory().openSession(); session.beginTransaction(); session.persist(apartment); session.getTransaction().commit(); session.close(); }