使用java框架构建移动应用程序的最佳实践是什么？

// MainActivity.java
public class MainActivity extends AppCompatActivity {

    private UserViewModel userViewModel;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        userViewModel = ViewModelProviders.of(this).get(UserViewModel.class);
        userViewModel.getUsers().observe(this, users -> {
            // Update the UI with the list of users
        });
    }
}

// UserViewModel.java
public class UserViewModel extends ViewModel {

    private UserRepository userRepository;

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

    public LiveData<List<User>> getUsers() {
        return userRepository.getAllUsers();
    }
}

// UserRepository.java
public class UserRepository {

    private UserService userService;

    public UserRepository(UserService userService) {
        this.userService = userService;
    }

    public LiveData<List<User>> getAllUsers() {
        return userService.getAllUsers();
    }
}

// UserService.java
public interface UserService {

    LiveData<List<User>> getAllUsers();
}