Is it ok to bind in interface with guice? the error is No implementation for com.tobris.apps.base.service.user.UserService was bound. UserService is an interface. @Inject public SyncContactService( PartnerRepository partnerRepo, CompanyRepository companyRepo, CityRepository cityRepo, CountryRepository countryRepo, AddressRepository addressRepo, SyncContactRepository syncContactRepo, EmailAddressRepository emailAddressRepo, UserService userService, FunctionRepository functionRepo) { this.partnerRepo = partnerRepo; this.companyRepo = companyRepo; this.cityRepo = cityRepo; this.countryRepo = countryRepo; this.addressRepo = addressRepo; this.syncContactRepo = syncContactRepo; this.emailAddressRepo = emailAddressRepo; this.userService = userService; this.functionRepo = functionRepo; } this is the binding code : // bind all the web service resources for (Class<?> type : ...