UserFactoryPublic.java

public class UserFactory {

    private UserRepository userRepository;

    public UserFactory(UserRepository userRepository) {
        this.userRepository = userRepository;
    }

    public User createUser(UserInfo userInfo) {
        String email = userInfo.getEmail();
        Optional<User> userFoundbyEmail = userRepository.findByEmail(email);

        if (userFoundbyEmail.isPresent()) {
            throw new UserEmailAlreadyUsedException();
        }
        if (isEmailInvalid(email)) {
            throw new InvalidUserEmailException();
        }
        return userRepository.save(mapToUser(userInfo));
    }


    private boolean isEmailInvalid(String userInfo) {
        // for example only
        return false;
    }

    private User mapToUser(UserInfo userInfo) {
        // for example only
        return null;
    }
}