Christian Panadero presented an approach called "My way to clean Android" which focuses on clean architecture principles like separation of concerns, testability, and decoupling. The key aspects discussed include using commands, interactors, abstractions, repositories, and data sources to separate layers. Dependencies follow a one-way rule from upper to lower layers. Examples demonstrate how to model projects with clean architecture, including MVP for the UI, repositories to abstract data sources, and strategies like caching. Advice includes working with abstractions, good naming, and starting in the correct layer. The clean code approach and references from experts like Uncle Bob and others are cited. Source code is provided on GitHub for further review.

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