Toothpick: repository with an interface

PrefUserRepository .java

public final class PrefUserRepository implements UserRepository {

    private final SharedPreferences sharedPreferences;

    @Inject
    public PrefUserRepository(SharedPreferences sharedPreferences) {
        this.sharedPreferences = sharedPreferences;
    }

    @Override
    public User getUser() {
        ...
    }

    @Override
    public void saveUser(User user) {
        ...
    }
}

UserRepository.java

public interface UserRepository {
    
    User getUser();

    void saveUser(User user);
}