Going Reactive with RxJava - @ TopConf Linz 2016

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Reactive Manifesto

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• • • •

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•

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• onNext • onCompleted • onError onNext onNext onNext onCompleted

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• onNext • onCompleted • onError onNext onNext onError

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• Observable.from • Observable.just • • Observable.interval , Observable.range , Observable.empty Observable intervalObservable = Observable.interval(500L, TimeUnit.MILLISECODS); Observable rangeObservable = Observable.range(1, 10); Observable justObservable = Observable.just('R', 'x', 'J', 'a', 'v', 'a'); List list = Arrays.asList("blue", "red", "green", "yellow", "orange"); Observable listObservable = Observable.from(list)

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• Observable.create public static Observable getData(String someParameter) { return Observable.create(subscriber -> { try { SomeDataType result = SomeService.getData(someParameter); subscriber.onNext(result); subscriber.onCompleted(); } catch (Exception e) { subscriber.onError(e); } }); }

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• observableInstance.subscribe observableInstance.subscribe(new Observer() { @Override public void onNext(SomeDataType message) { // Do something on each Message received } @Override public void onError(Throwable error) { // Do something on Error } @Override public void onCompleted() { // Do something when Observable completes } });

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• observableInstance.subscribe observableInstance.subscribe( (SomeDataType message) -> {/*onNext*/}, (Throwable error) -> {/*onError*/}, () -> {/*onCompleted*/});

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• • • • • •

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• • • • • •

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• • • • observableInstance.filter(element -> element < 10) observableInstance.timeout(100, TimeUnit.MILLISECONDS) observableInstance.map(number -> number * number) Observable mergedObservable = Observable .merge(firstObservable, secondObservable, thirdObservable);

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Observable.range(1,9) .skipWhile(element -> element < 5) .take(3) .reduce((elem1, elem2) -> elem1 + elem2) .subscribe(result -> /*do something*/)

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• try/catch • • onError • onNext onNext onError

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• • • onError , onErrorReturn , onErrorResumeNext, retry mainObservable.onErrorReturn(throwable -> { System.out.println("The original feed failed with" + throwable); return oneMoreMessage; }).subscribe(data -> {/* doSomething */}); mainObservable.onErrorResumeNext(throwable -> { System.out.println("The original feed failed with" + throwable); return backupObservable; }).subscribe(data -> {/* doSomething */});

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• • • •

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main

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main observable.subscribe (onNext, onCompleted)

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main observable.subscribe (onNext, onCompleted) observable.subscribe remoteService.getData()

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main observable.subscribe (onNext, onCompleted) observable.subscribe remoteService.getData() remoteService.getData

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main observable.subscribe (onNext, onCompleted) observable.subscribe remoteService.getData() subscriber.onNext(data)

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main observable.subscribe (onNext, onCompleted) observable.subscribe remoteService.getData() subscriber.onNext(data) subscriber.onNext

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main observable.subscribe (onNext, onCompleted) observable.subscribe remoteService.getData() subscriber.onNext(data) subscriber.onCompleted()

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main observable.subscribe (onNext, onCompleted) observable.subscribe remoteService.getData() subscriber.onNext(data) subscriber.onCompleted() subscriber.onCompleted

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main observable.subscribe (onNext, onCompleted) observable.subscribe remoteService.getData() subscriber.onNext(data) subscriber.onCompleted()

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main observable.subscribe (onNext, onCompleted) remoteService.getData() subscriber.onNext(data) subscriber.onCompleted()

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observable.subscribe (onNext, onCompleted) remoteService.getData() subscriber.onNext(data) subscriber.onCompleted()

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• Observable • subscribeOn(Scheduler) • observeOn(Scheduler) • Schedulers • immediate – • newThread – • trampoline – • io – • computation –

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observable .subscribeOn(Schedulers.io()) .observeOn(Schedulers.computation()) .subscribe(onNext, onCompleted)

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observable .subscribeOn(Schedulers.io()) .observeOn(Schedulers.computation()) .subscribe(onNext, onCompleted) remoteService.getData() subscriber.onNext(data)

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observable .subscribeOn(Schedulers.io()) .observeOn(Schedulers.computation()) .subscribe(onNext, onCompleted) remoteService.getData() subscriber.onNext(data)

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observable .subscribeOn(Schedulers.io()) .observeOn(Schedulers.computation()) .subscribe(onNext, onCompleted) remoteService.getData() subscriber.onNext(data) subscriber.onCompleted()

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• • subscribe • • unsubscribe

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• Subscription subscription = observableInstance.subscribe( (Long message) -> {/*onNext*/}, (Throwable error) -> {/*onError*/}, () -> {/*onCompleted*/}); // Do some logic; subscription.unsubscribe();

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• observableInstance.subscribe(new Subscriber() { @Override public void onNext(Long message) { // Do something on each Message received unsubscribe(); } @Override public void onError(Throwable e) { // Do something on Error } @Override public void onCompleted() { // Do something when Observable completes } });