Reactive Programming no Android

11
REACTIVE PROGRAMMING NO ANDROID
Guilherme Branco
Software Engineer
Guilherme Pereira Branco
@guipbranco

22
REACTIVE PROGRAMMING NO ANDROID
Guilherme Branco
Software Engineer
Guilherme Pereira Branco
@guipbranco

Reactive Programming
é do balacobaco!
Quem não usa está
por fora, meu!
Sou deveras
experiente em RxJava!

66
Reactive Programming | O Que é?
• Pull x Push: Ao invés de pedir algo e esperar, o desenvolvedor
simplesmente pede por algo e é notificado quando o resultado estiver
disponível.
• Paradigma baseado no conceito de fluxo de dados assíncrono.
• Mais flexível. O Desenvolvedor ignora se os dados chegam de forma
síncrona ou assíncrona. O código simplesmente funciona.
• Fontes de dados podem ser combinadas e não aninhadas, afastando o
desenvolvedor do “callback hell”

77
Observable Observer
Emite
item1
item2
item3
Manipula item 1
Manipula item 2
Manipula item 3
onNext(item1)
onNext(item2)
onNext(item3)
Itens acabaram onCompleted() completar
Ops! Erro… onError(error) Trata erro
Reactive Programming | Fluxo

99
Anatomia | Principal Construção
Observable.from(lectureService.getLectures()) 1. Observable
.subcribeOn(Schedulers.io()).observeOn(AndroidSchedulers.mainThread()) 3. Schedulers
.subscribe(getObserver()) 2. Observer

1010
public interface LectureService {
List<Lecture> getLectures();
}

1111

1212
Anatomia | Observer / Subscriber
private Observer<Lecture> getObserver(){
return new Observer<Lecture>() {
@Override
public void onCompleted() {
Log.e(TAG, "onCompleted");
}
@Override
public void onError(Throwable e) {
Log.e(TAG, "onError: " + e.getMessage());
}
@Override
public void onNext(Lecture lecture){
Log.e(TAG, "onNext");
}
});

1313
ObserverObservable
=
4. Subscription

1414
.subcribeOn(Schedulers.io()).observeOn(AndroidSchedulers.mainThread())
.subscribe(getObserver())
Observable<Lecture> observable = Observable.from(lectureService.getLectures()) ;
observableSubscription subscription =
1. subscription.unsubscribe()
2. CompositeSubscription compSubscription;
compSubscription.add(subscription);
3. compSubscription.unsubscribe()

1616
public interface LectureService {
List<Lecture> getLectures();
}
Exemplo | AsyncTask

1717
new LectureAsyncTask().execute();
private class LectureAsyncTask
extends AsyncTask<String, Void, List<Lecture>>{
@Override
protected void onPreExecute() {
showLoading();
}
@Override
protected List<Lecture> doInBackground(String... params){
return lectureService.getLectures();
}
@Override
protected void onPostExecute(List<Lecture> lectures){
hideLoading();
renderItems(lectures);
}
}
Anatomia | AsyncTask -> Reactive

1818
@Override
showLoading();
}
@Override
}
@Override
hideLoading();
}
}
Observable.from(lectureService.getLectures())
.doOnSubscribe(showLoading())
.subscribeOn(Schedulers.io())
.toList()

1919
.toList()

2020
@Override
showLoading();
}
@Override
}
@Override
hideLoading();
}
}
.subscribe(
new Subscriber<List<Lecture>>() {
@Override
hideLoading();
}
@Override
}
@Override
public void onNext(List<Lecture> lectures){
}
});
.toList()

2121
.subscribe(
@Override
hideLoading();
}
@Override
}
@Override
}
});

2222
@Override
showLoading();
}
@Override
}
@Override
hideLoading();
}
}
.subscribe(
@Override
hideLoading();
}
@Override
}
@Override
}
});
.toList()

2323
Exemplo | AsyncTask -> Reactive
android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.

2424
@Override
showLoading();
}
@Override
}
@Override
hideLoading();
}
}
.subscribe(
@Override
hideLoading();
}
@Override
}
@Override
}
});
.toList()

2525
.subscribe(
@Override
hideLoading();
}
@Override
}
@Override
}
});
.observeOn(AndroidSchedulers.mainThread())
.toList()

2626
Exemplo | RxJava
.subscribe(new Subscriber(){…});
.toList()

2828
.toList()
Exemplo | RxJava

2929
Operator | Filter
.filter(new Func1<Lecture, Boolean>() {
@Override
public Boolean call(Lecture lecture) {
return lecture.getDay().equalsIgnoreCase(day);
}
})
.toList()

3232
Observable<Lecture> observable = getLectures();
.map(new Func1<Lecture, String>() {
@Override
public String call(Lecture lecture) {
return lecture.getDay();
}
}) // Observable<String>
.cast(CharSequence.class) // Observable<CharSequence>
Operator | Map, Cast, Distinct…
.distinct() // Mesmo Observable sem dados repetidos
.toList() // Observable<List<CharSequence>>
observable

3333
Reactive Programming | Links
https://github.com/ReactiveX/RxJava
https://www.packtpub.com/application-development/rxjava-essentials
http://rxmarbles.com

34
http://github.com/gpbranco/rx-example-tdc

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