The document discusses using MVVM with RxJava in Kotlin for Android development. It introduces MVVM and RxJava concepts and patterns, provides code examples of implementing MVVM with RxJava in Kotlin, and discusses testing MVVM ViewModels. It also compares MVVM to MVP and discusses where each pattern is appropriate.

1. MVVM com RxJava em Kotlin no
Android

2. GDGFoz
Quem ?
• Houssan Ali Hijazi - hussanhijazi@gmail.com
• Desenvolvedor Android na www.HElabs.com
• Organizador GDG Foz do Iguaçu
• www.lojasnoparaguai.com.br
• www.desaparecidosbr.org
• www.hussan.com.br

3. GDGFoz
Kotlin
• 2011/JetBrains
• 1.0 em Fev. 2016
• 1.1 em Mar. 2017
• Pinterest, Coursera, Netflix, Uber, Square, Trello e
Basecamp
• 17/Maio - Google IO 2017

4. GDGFoz
Kotlin
• Interoperabilidade
• Null Safety
• Conciso

5. GDGFoz
Manifesto reativo
• Responsivo - Reagir rápido
• Resiliente - Reagir a falhas
• Elástico - Reagir a carga / Autoescalar
• Orientado a mensagens - Comunicação
assíncrona
Fonte: https://www.reactivemanifesto.org/pt-BR

6. GDGFoz
RxJava
• RxJava - Reactive Extensions para a JVM - uma
biblioteca para compor programas assíncronos e
baseados em eventos usando sequências
observáveis.
• Netflix
• 1.0.0 em 18 Nov 2014
• 2.0.0 em 28 Out 2016

7. GDGFoz
RxJava
Observable
Disposable
subscribe(Observer<T>)
Emite
Observer
onNext(T)
onComplete()
onError(Throwable)
Consome

8. GDGFoz
RxJava
• Observable - Emite dados
• Observer - Consome dados
• Disposable
• Operators: map, flatmap, filter, last, first etc..
• Schedulers

9. GDGFoz
Código
• Robusto
• Estável
• Testável
• Modular

10. GDGFoz
Model/View/Controller
Activity
IView

11. GDGFoz
Model/View/Presenter
Contract

12. GDGFoz
App

13. GDGFoz
Model/View/Presenter
// View contract
interface RepositoriesContract{
interface View{
fun setRepositories(repositories: List<Repository>)
}
}
// Activity/Fragment
class RepositoriesActivity : AppCompatActivity(), RepositoriesContract.View {
...
// Passing the View to Presenter
presenter = RepositoriesPresenter(this)
override fun setRepositories(repositories: List<Repository>) {
// Setting data to view
}

14. GDGFoz
Model/View/Presenter
// Presenter contract
interface RepositoriesContract {
interface Presenter {
fun getAllRepositories()
}
}
// Passing View to Presenter
class RepositoriesPresenter(val view: RepositoriesContract.View): RepositoriesContract.Presenter
lateinit var model: RepositoryModel
override fun getAllRepositories() {
// Call model and set data to View
// Can be RxJava
var repositories:List<Repository> = model.getAllRepositories()
view.setRepositories(repositories)
}

15. GDGFoz
Model/View/ViewModel
• Microsoft
• 2005
• Orientado à eventos

16. GDGFoz
Model/View/ViewModel

17. GDGFoz
MVVM
// ViewModel
class RepositoriesViewModel(var model: RepositoryDataSource) {
...
fun getAllRepositories() {
// Return an Observable
fun getAllRepositories(): Observable<List<Repository>> = model.getAllRepositories()
}

18. GDGFoz
MVVM
// Activity/Fragment
class RepositoriesActivity : AppCompatActivity() {
private val viewModel: RepositoriesViewModel by lazy {
RepositoriesViewModel(RepositoryModel())
}
private val mDisposable = CompositeDisposable()
...

19. GDGFoz
MVVM
// Activity/Fragment
override fun onCreate(savedInstanceState: Bundle?) {
...
mDisposable.add(
viewModel.getAllRepositories()
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(
// onNext
this::setRepositories,
// onError
{ error -> Log.d(TAG, "Error: ", error) },
// onComplete
{ Log.d(TAG, "Completed: ") }
)
)
// Activity/Fragment
fun setRepositories(repositories: List<Repository>) {
// Setting data to view
}

20. GDGFoz
Android lifecycle
// Activity/Fragment
override fun onDestroy() {
super.onDestroy()
mDisposable.dispose()
}

21. GDGFoz
MVP/MVVM
class Presenter: IPresenter {
override fun getAllRepositories() {
...
view.setRepositories(repositories)
}
}
class ViewModel {
fun getAllRepositories(): Observable<List<Repository>> {
...
}
}

22. GDGFoz
MVVM tests
class RepositoriesViewModelTest {
@Mock
lateinit var model: RepositoryDataSource
lateinit var viewModel: RepositoriesViewModel
…
@Before
fun setup()
{
model = mock()
viewModel = RepositoriesViewModel(model)
}

23. GDGFoz
MVVM tests
@Test
fun `get repositories emit correct values`() {
val repositories = listOf(Repository(name = "Test"), Repository(name = "Test2"
`when`(model.getAllRepositories()).thenReturn(Observable.just(repositories))
viewModel.getAllRepositories()
.test()
.assertNoErrors()
.assertComplete()
.assertValue(repositories)
}

24. GDGFoz
Save states
// Save
override fun onSaveInstanceState(state: Bundle?) {
super.onSaveInstanceState(state)
//Can create Bundle here
state.putAll(viewModel.getState())
}
// Restore
override fun onRestoreInstanceState(bundle: Bundle) {
super.onRestoreInstanceState(bundle)
viewModel.restoreState(bundle)
}

25. GDGFoz
Activity
Fragment
CustomView
CustomView
P / VM
View

26. GDGFoz
Lógica de UI ?
• Tem lógica de UI ?
• Sim - Presenter/ViewModel (Testes)
• Não - View

27. GDGFoz
Qual ?
• Classes Android sem lógica ?
• Pode ser testado (unit test) ?
• Suas classes tem uma responsabilidade bem
definida ?

28. GDGFoz
Links
• http://reactivex.io/
• https://github.com/ReactiveX/RxJava/
• https://kotlinlang.org/
• https://medium.com/upday-devs/android-architecture-patterns-part-3-
model-view-viewmodel-e7eeee76b73b
• https://github.com/googlesamples/android-architecture
• https://github.com/hussanhijazi/retrofit-rxjava-databinding/tree/kotlin-mvvm

29. Obrigado