My way to clean android implementation

1. Christian Panadero
http://panavtec.me
@PaNaVTEC
Github - PaNaVTEC
My way to clean Android

2. Fernando Cejas Jorge Barroso
Pedro Gomez Sergio Rodrigo
@fernando_cejas @flipper83
@pedro_g_s @srodrigoDev
Android developer en Sound Cloud
Android developer en Tuenti
Cofounder & Android expert en Karumi
Android developer en Develapps
Alberto Moraga Carlos Morera
@albertomoraga @CarlosMChica
iOS Developer en Selltag Android Developer en Viagogo
Agradecimientos

3. “My way to clean Android”

4. ¿Por qué Clean?
• Desacoplado de los frameworks
• Testable
• Desacoplado de la UI
• Desacoplado de BDD
• Desacoplado de cualquier detalle de
implementación

5. Conceptos
• Patrón command (Invoker, command, receiver)
• Interactors / Casos de uso
• Abstracciones
• Data Source
• Repository

6. Niveles de abstracción
Presenters
Interactors
Entidades
Repository
Data sources
UI
Abstractions

7. Regla de dependencias
Presenters
Interactors
Entidades
Repository
Data sources
UI
Abstractions

8. Modelando el proyecto
• App (UI, DI y detalles de implementación)
• Presentation
• Domain y Entities
• Repository
• Data Sources

9. Dependencias del proyecto
App
Presenters Domain Data
Entities
Repository

10. Flow
View
Presenter
Presenter
Interactor
Interactor
Interactor
Interactor
Repository
Repository
DataSource
DataSource
DataSource

11. UI: MVP
ViewPresenter(s)
Model
Eventos
Rellena la vista
Acciones
Resultados de
esas acciones

12. UI: MVP - View
public class MainActivity extends BaseActivity implements MainView {
@Inject MainPresenter presenter;
@Override protected void onResume() {
super.onResume();
presenter.onResume();
}
@Override public void onRefresh() {
presenter.onRefresh();
}

13. UI: MVP - Presenter
public class MainPresenter extends Presenter {
private MainView mainView;
private Bus bus;
public void onResume() {
bus.register(this);
}
public void onPause() {
bus.unregister(this);
}
public void onRefresh() {
mainView.clearData();
…
}

14. public interface MainView {
void showGetContactsError();
void clearData();
}
UI: MVP - Presenter

15. Presentation - Domain
Presenter InteractorInvoker
Bus
Bus IMP
Invoker IMP

16. Presentation - Domain
public class MainPresenter extends Presenter {
public void onCreate() {
interactorInvoker.execute(getContactsInteractor);
}
public void onEvent(GetContactsEvent event) {
if (event.getError() == null) {
List<PresentationContact> contacts = event.getContacts();
mainView.refreshContactsList(contacts);
} else {
mainView.showGetContactsError();
}
}

17. public class GetContactsInteractor implements Interactor {
private Bus bus;
private ContactsRepository repository;
@Override public void execute() {
GetContactsEvent event = new GetContactsEvent();
try {
List<Contact> contacts = repository.obtainContacts();
event.setContacts(contacts);
} catch (RetrieveContactsException e) {
event.setError(e);
}
bus.post(event);
}
}
Domain - Interactor

18. Repository
Network
Data Source
BDD
Data Source
Repository
Model
Data

19. Repository Interface
public interface ContactsRepository {
List<Contact> obtainContacts() throws
CantRetrieveContactsException;
Contact obtain(String md5) throws
CannotObtainContactException;
}

20. Repository imp
@Override public List<Contact> obtainContacts() throws
RetrieveContactsException {
List<Contact> contacts = null;
try {
contacts = bddDataSource.obtainContacts();
} catch (ObtainContactsBddException | InvalidCacheException e) {
try {
contacts = networkDataSource.obtainContacts();
bddDataSource.persist(contacts);
} catch (UnknownObtainContactsException | ContactsNetworkException) {
throw new RetrieveContactsException();
} catch (PersistContactsBddException) {
e.printStackTrace();
}
}
return contacts;
}

21. Data source
Model
Data source Imp
Data source
Mapper

22. Data source Interface
public interface ContactsNetworkDataSource {
public List<Contact> obtainContacts() throws
ContactsNetworkException, UnknownObtainContactsException;
}

23. private ContactsApiService apiService;
private static final ApiContactMapper mapper = new ApiContactMapper();
@Override public List<Contact> obtainContacts() throws ContactsNetworkException
{
try {
ApiContactsResponse apiContactsResponse = apiService.obtainUsers(100);
List<ApiContactResult> results = apiContactsResponse.getResults();
<MAP APICONTACTS TO CONTACTS>
return contacts;
} catch (Throwable e) {
throw new ContactsNetworkException();
}
}
Data source imp

24. Caching Strategy
public interface CachingStrategy<T> {
boolean isValid(T data);
}
public TtlCachingStrategy(int ttl, TimeUnit timeUnit) {
ttlMillis = timeUnit.toMillis(ttl);
}
@Override public boolean isValid(T data) {
return (data.getPersistedTime() + ttlMillis) >
System.currentTimeMillis();
}

25. Caching Strategy
@Override public List<Contact> obtainContacts()
throws ObtainContactsBddException, UnknownObtainContactsException,
InvalidCacheException {
try {
List<BddContact> bddContacts = daoContacts.queryForAll();
if (!cachingStrategy.isValid(bddContacts)) {
deleteBddContacts(cachingStrategy.candidatesToPurgue(bddContacts));
throw new InvalidCacheException();
}
ArrayList<Contact> contacts = new ArrayList<>();
for (BddContact bddContact : bddContacts) {
contacts.add(transformer.transform(bddContact, Contact.class));
}
return contacts;
} catch (java.sql.SQLException e) {
throw new ObtainContactsBddException();
} catch (Throwable e) {
throw new UnknownObtainContactsException();
}
}

26. Ventajas de Repository
• La lógica de negocio no sabe de donde vienen los
datos.
• Fácil de cambiar la implementación de los
orígenes de datos.
• En caso de cambio de orígenes de datos la lógica
de negocio no se ve alterada.

27. – Uncle Bob
“Make implementation details swappable”

28. Picasso
public interface ImageLoader {
public void load(String url, ImageView imageView);
public void loadCircular(String url, ImageView imageView);
}
public class PicassoImageLoader implements ImageLoader {
private Picasso picasso;
public PicassoImageLoader(Picasso picasso) {
this.picasso = picasso;
}
public void load(String url, ImageView imageView) {
picasso.load(url).into(imageView);
}
@Override public void loadCircular(String url, ImageView imageView) {
picasso.load(url).transform(new CircleTransform()).into(imageView);
}

29. ErrorManager
public interface ErrorManager {
public void showError(String error);
}
public class SnackbarErrorManagerImp implements ErrorManager {
@Override public void showError(String error) {
SnackbarManager.show(Snackbar.with(activity).text(error));
}
}
public class ToastErrorManagerImp implements ErrorManager {
@Override public void showError(String error) {
Toast.makeText(activity, error,
Toast.LENGTH_LONG).show();
}
}

30. Consejos
• Trabaja siempre con abstracciones nunca con
concreciones.
• Usa un buen naming, si ves que hay alguna figura
que has creado que no sabes que nombre poner,
seguramente esté mal modelada.
• Si creas nuevas figuras usa la diana inicial para
asegurarte que las creas en la capa
correspondiente

31. – Uncle Bob
“Clean code. The last programming
language”

32. In Uncle Bob we trust

33. Show me the code!
https://github.com/PaNaVTEC/Clean-Contacts

34. Referencias
• Fernando Cejas - Clean way
• Jorge Barroso - Arquitectura Tuenti
• Pedro Gomez - Dependency Injection
• Pedro Gomez - Desing patterns
• Uncle Bob - The clean architecture

35. ¿Preguntas?
Christian Panadero
http://panavtec.me
@PaNaVTEC
Github - PaNaVTEC