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Intro to reactive programing
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Fernando Franco Gíraldez
December 01, 2021
Programming
0
45
Intro to reactive programing
Small introduction into rx-java 2.X and it's core element and how to use it
Fernando Franco Gíraldez
December 01, 2021
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Transcript
Intro To Reactive programing
Schedule ▸ What is reactive programming ▸ Core elements of
rx-java ▸ How to test your reactive chains 2
“ The world has move to push; user are waiting
for us to catch up Lee Campbell - Introduction to Rx
1. What is reactive programing A brief description 4
Mixing of ideas Observable Pattern Iterable Pattern FP style 5
What is reactive programing It’s a library for composing asynchronous
and event based programs by using observable sequences 6
2. Core elements 7
Core elements \ concepts ▸ Observable ▸ Operators ▸ Observer
▸ Disposable ▸ Threading 8
Core elements \ events ▸ onNext ▸ onComplete ▸ onError
9
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
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
Core elements \ Observable \ Specialization ▸ Observable ▸ Single
▸ Completable ▸ Maybe ▸ Flowable 12
Core elements \ Operators 13
Core elements \ Operators 14 networkRequestSingle.map { response -> response.result.name
}
Core elements \ Operators 15 textWatcherObservable.debounce(400, TimeUnit.MILLISECONDS)
Core elements \ Operators 16 suggestionTextWatcher.debounce(400, TimeUnit.MILLISECONDS) .switchMapSingle { repo.searchSuggestion(it)
}
Core elements \ Operators 17 suggestionTextWatcher.doOnNext { loading.postValue(true) } .switchMapSingle
{ repo.searchSuggestion(it) } .doOnSubscribe { loading.postValue(false) }
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
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
Core elements \ Disposable val disposable = suggestionTextWatcher .subscribe {
results.postValue(it) } disposable.isDisposed() disposable.dispose() val compositeDisposable = CompositeDisposable() disposable.add(suggestionTextWatcher.subscribe{}) disposable.clear() 20
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
suggestionTextWatcher.switchMapSingle { repo.searchSuggestion(it) } .subscribeOn(Schedulers.io()) .observeOn(AndroidSchedulers.mainThread()) Core elements \ Threading
22 Specify the Scheduler on which an Observable will operate.
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.
Testing ▸ How to provide Schedulers? ▸ Make test run
faster ▸ Use black box testing strategies 24
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
Testing \ TestObserver Val testObserver = voiceRecognition.observe().test(); testObserver.assertValues(....); testObserver.isTerminated() testObserver.assertSubscribed()
26
27 THANKS! Any questions? @thanerian
[email protected]