Intro to reactive programing

Small introduction into rx-java 2.X and it's core element and how to use it

Transcript

1. Intro To Reactive programing
2. Schedule ▸ What is reactive programming ▸ Core elements of rx-java ▸ How to test your reactive chains 2
3. “ The world has move to push; user are waiting for us to catch up Lee Campbell - Introduction to Rx
4. 1. What is reactive programing A brief description 4
5. Mixing of ideas Observable Pattern Iterable Pattern FP style 5
6. What is reactive programing It’s a library for composing asynchronous and event based programs by using observable sequences 6
7. 2. Core elements 7
8. Core elements \ concepts ▸ Observable ▸ Operators ▸ Observer ▸ Disposable ▸ Threading 8
9. Core elements \ events ▸ onNext ▸ onComplete ▸ onError 9
10. Core elements \ Observable Observable.create { emitter -> try { if (!emitter.isDisposed) { emitter.onNext("rxjava FTW!") emitter.onNext("functional programing FTW!") emitter.onComplete() } } catch (exception: Exception) { emitter.onError(exception) } } 10
11. Core elements \ Observable Observable.create { emitter -> val receiver = object : BroadcastReceiver() { override fun onReceive(context: Context, intent: Intent) = emitter.onNext(intent) } context.registerReceiver(receiver, IntentFilter()) emitter.setCancellable { context.unregisterReceiver(receiver) } } 11
12. Core elements \ Observable \ Specialization ▸ Observable ▸ Single ▸ Completable ▸ Maybe ▸ Flowable 12
13. Core elements \ Operators 13
14. Core elements \ Operators 14 networkRequestSingle.map { response -> response.result.name }
15. Core elements \ Operators 15 textWatcherObservable.debounce(400, TimeUnit.MILLISECONDS)
16. Core elements \ Operators 16 suggestionTextWatcher.debounce(400, TimeUnit.MILLISECONDS) .switchMapSingle { repo.searchSuggestion(it) }
17. Core elements \ Operators 17 suggestionTextWatcher.doOnNext { loading.postValue(true) } .switchMapSingle { repo.searchSuggestion(it) } .doOnSubscribe { loading.postValue(false) }
18. Core elements \ Observer val observer = object: Observer<String>{ override fun onNext(t: String) {} override fun onError(e: Throwable) {} override fun onComplete() {} override fun onSubscribe(d: Disposable) {} } 18
19. Core elements \ Observer suggestionTextWatcher .switchMapSingle { repo.searchSuggestion(it) } .subscribe(observer) .subscribe { results.postValue(it) } .subscribe({ results -> }, { throwable -> }) .subscribe({ results -> }, { throwable -> }, {}) .subscribeBy( onNext = { results -> }, onError = { throwable -> }, onComplete = {} ) 19
20. Core elements \ Disposable val disposable = suggestionTextWatcher .subscribe { results.postValue(it) } disposable.isDisposed() disposable.dispose() val compositeDisposable = CompositeDisposable() disposable.add(suggestionTextWatcher.subscribe{}) disposable.clear() 20
21. suggestionTextWatcher.switchMapSingle { repo.searchSuggestion(it) } .subscribeOn(Schedulers.io()) .observeOn(AndroidSchedulers.mainThread()) Core elements \ Threading 21 To add concurrency into our observable sequence, just indicate to the observable to operate in a particular Scheduler
22. suggestionTextWatcher.switchMapSingle { repo.searchSuggestion(it) } .subscribeOn(Schedulers.io()) .observeOn(AndroidSchedulers.mainThread()) Core elements \ Threading 22 Specify the Scheduler on which an Observable will operate.
23. suggestionTextWatcher.switchMapSingle { repo.searchSuggestion(it) } .subscribeOn(Schedulers.io()) .observeOn(AndroidSchedulers.mainThread()) Core elements \ Threading 23 Specify the Scheduler on which an Observer will observe this observable.
24. Testing ▸ How to provide Schedulers? ▸ Make test run faster ▸ Use black box testing strategies 24
25. Testing \ Schedulers val testScheduler = TestScheduler() RxJavaPlugins.setIoSchedulerHandler( scheduler -> testScheduler); RxAndroidPlugins.setMainThreadSchedulerHandler( scheduler -> Schedulers.trampoline()); @field:Rule val testSchedulers = TestSchedulerRule.create(); testScheduler.advanceTimeBy(30, TimeUnit.SECONDS); 25
26. Testing \ TestObserver Val testObserver = voiceRecognition.observe().test(); testObserver.assertValues(....); testObserver.isTerminated() testObserver.assertSubscribed() 26
27. 27 THANKS! Any questions? @thanerian ffrancogiraldez@gmail.com