guice : No implementation for interface was bound-CodePudding

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 :
        MetaScanner.findSubTypesOf(Object.class)
            .having(Path.class)
            .having(Provider.class)
            .any()
            .find()) {
      bind(type);
    }

CodePudding user response：

When you bind() a type, you actually bind that type and not any of its interfaces. Guice works with explicit bindings, not implicit ones.

So what you should do is the following:

ScopedBindingBuilder bindAutomaticImplementation(Class<?> baseType) {
  var implementations = MetaScanner.findSubTypesOf(Object.class)
            .having(Path.class)
            .having(Provider.class)
            .any()
            .find();
  if (implementations.size() != 1) {
    throw new RuntimeException("Too many or too few implementations for "   baseType);
  }
  var implementation = implementation.iterator().next();
  return bind(baseType.class).to(implementation);
}

Then, you have to explicitly bind the types you want:

bindAutomaticImplementation(UserService.class).in(Singleton.class);