reactive programming in android
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Reactive Programming in AndroidALDRIN SEYCHELL
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Modern ComputingAND MOBILE PHONES …
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What’s reactive programming?◦ Data Flows◦ Asynchronous◦ Event-driven◦ Abstraction from concerns
◦ Low Level Threading◦ Synchonization◦ Side effects
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Side effects have Latency◦ Reading a file◦ Calling an API◦ Data Processing◦ Etc …
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Effects of ProgrammingSingle Many
Synchronous T getData() Iterable<T> getData()
Asynchronous Future<T> getData() Observable<T> getData()
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Why Reactive Programming?◦ Reacting asynchronously to user interactions
◦ E.g. Text Input, Clicks on a button
◦ Composition of operations on stream of events◦ E.g. Accumulating clicks and/or text input changes
◦ Achieving non-blocking async operations◦ Abstraction to reason on different threads◦ Loading images into bitmaps
◦ Auto-completion with throttling◦ Avoid overloading of server
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Observablespublic class Observable<T> {
Subscription subscribe(Subscriber<T> subscriber);...
}
public class Subscriber<T> {void onCompleted();void onError(Throwable e);void onNext(T t);
}
Asynchronous stream of events
Used to unsubscribe
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Rx in Android (RxAndroid)◦ Reactive UI Components
◦ Such as TextViews, Buttons
◦ Easy to reason on UI Thread◦ Using Android Schedulers
◦ https://github.com/ReactiveX/RxAndroid◦ Based on RxJava
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Composing Observables◦ Transform: map, flatMap, reduce, scan◦ Filter: take, filter, skip, sample, debounce◦ Combine: concat, merge, zip◦ Concurrency: observeOn, subscribeOn◦ Error Handling: onErrorReturn
Similar to Java 8/Scala collections but items except results are emitted when they arrive
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Android Primer (Layouts)
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Android Primer (Activity)◦ Has a layout◦ Holds the logic associated with a screen◦ Has its own lifecycle◦ Can update its own views
◦ Only on the main thread!
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Demo
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References◦ https://github.com/ReactiveX/RxAndroid◦ http://plainoldobjects.com/presentations/decomposing-applications-for-deployability-and-
scalability/futures-and-rx-observables-powerful-abstractions-for-consuming-web-services-asynchronously/
◦ https://github.com/kaushikgopal/Android-RxJava◦ http://www.slideshare.net/Tomik/reactive-programming-on-android?related=1
