RxAndroid at #JavaSkop

A short presentation about RxAndroid that I was supposed to give at #JavaSkop.

Transcript

1. RxAndroid RxJava for Android
2. #JavaSkop · stojan.me · RxAndroid 2 Stojan Dimitrovski Android Software Engineer Netcetera stojan.me
3. #JavaSkop · stojan.me · RxAndroid 3 Rx = Reactive Extensions “Special” data processing API. Introduced by Microsoft for .NET. RxJava, RxClojure, RxCpp... reactivex.io
4. #JavaSkop · stojan.me · RxAndroid 4 The Big Picture
5. #JavaSkop · stojan.me · RxAndroid 5 Observable A sequential process that generates data.
6. #JavaSkop · stojan.me · RxAndroid 6 COOKIE COOKIE FACTORY FACTORY An Observable Process
7. #JavaSkop · stojan.me · RxAndroid 7 Observer
8. #JavaSkop · stojan.me · RxAndroid 8 STOP MAKING COOKIES STOP THE COOKIES
9. #JavaSkop · stojan.me · RxAndroid 9 How does this help? Observables are black boxes that produce data. Single Responsibility Observers consume data. Information Hiding Subscriptions are the glue. Weak Coupling
10. #JavaSkop · stojan.me · RxAndroid 10 RxJava + RxAndroid RxAndroid = RxJava + Main Thread Scheduler
11. #JavaSkop · stojan.me · RxAndroid 11 interface CookieFactory { /** Makes cookies for consumption. */ Observable<Cookie> cookies(); } cookieFactory.cookies().forEach(/* onNext */ new Action1<>() { @Override public void call(Cookie cookie) { eat(cookie); } }, /* onError */ new Action1<>() { @Override public void call(Throwable throwable) { call(911); } }, /* onCompleted */ new Action0() { @Override public void call() { cry(); } });
12. #JavaSkop · stojan.me · RxAndroid 12 interface CookieFactory { /** Makes cookies for consumption. */ Observable<Cookie> cookies(); } cookieFactory.cookies().forEach(/* onNext */ new Action1<>() { @Override public void call(Cookie cookie) { eat(cookie); } }, /* onError */ new Action1<>() { @Override public void call(Throwable throwable) { call(911); } }, /* onCompleted */ new Action0() { @Override public void call() { cry(); } });
13. #JavaSkop · stojan.me · RxAndroid 13 interface CookieFactory { /** Makes cookies for consumption. */ Observable<Cookie> cookies(); } cookieFactory.cookies().forEach(/* onNext */ new Action1<>() { @Override public void call(Cookie cookie) { eat(cookie); } }, /* onError */ new Action1<>() { @Override public void call(Throwable throwable) { call(911); } }, /* onCompleted */ new Action0() { @Override public void call() { cry(); } });
14. #JavaSkop · stojan.me · RxAndroid 14 interface CookieFactory { /** Makes cookies for consumption. */ Observable<Cookie> cookies(); } cookieFactory.cookies().forEach(/* onNext */ new Action1<>() { @Override public void call(Cookie cookie) { eat(cookie); } }, /* onError */ new Action1<>() { @Override public void call(Throwable throwable) { call(911); } }, /* onCompleted */ new Action0() { @Override public void call() { cry(); } });
15. #JavaSkop · stojan.me · RxAndroid 15 /** Makes boxes of cookies. */ Observable<DeliciousBox> boxesOfCookies() { return cookies().buffer(10).map(new Func1<...>() { @Override public DeliciousBox call(List<Cookie> cookies) { return package(cookies); } }; }
16. #JavaSkop · stojan.me · RxAndroid 16 /** Makes boxes of cookies on a new thread. */ Observable<DeliciousBox> boxesOfCookies() { return cookies() .subscribeOn(Schedulers.newThread()) .buffer(10) .map(new Func1<...>() { @Override public DeliciousBox call(List<Cookie> cookies) { return package(cookies); } }; }}
17. #JavaSkop · stojan.me · RxAndroid 17 cookies() boxesOfCookies()
18. #JavaSkop · stojan.me · RxAndroid 18 class MainAtivity extends Activity { Subscription friends; @Override public void onResume() { friends = Facebook.friendsFor(user) // loading of friends happens on a new thread .subscribeOn(Schedulers.newThread()) // friends are shown on the main thread .observeOn(AndroidSchedulers.mainThread()) .subscribe( /* onNext */ showFriend, /* onError */ showError, /* onCompleted */ yay); } @Override public void onPause() { // stops the process, kills the thread // disconnects HTTP request friends.unsubscribe(); } }
19. #JavaSkop · stojan.me · RxAndroid 19 Observable.create(new Observable.OnSubscribe<Cookie>() { @Override public void call(Subscriber<Cookie> subscriber) { // blocking is OK here try { while (!subscriber.isSubscribed()) { // make the cookies while we have someone to eat them subscriber.onNext(makeCookie()); } subscriber.onCompleted(); } catch (Throwable t) { subscriber.onError(t); } } });
20. #JavaSkop · stojan.me · RxAndroid 20 What You Get 1. Process decoupled from implementation, place of execution. 2. Composition of processes to form new processes. 3. Testable code. Yay for Quality! 4. Synchronization no longer a (big) issue. 5. Truly cancellable operations. (More or less.)
21. #JavaSkop · stojan.me · RxAndroid 21 Things to Have in Mind 1. Keep data immutable. 2. Order of subscribeOn / observeOn does not matter. 3. Call subscribeOn / observeOn before subscription. 4. Use toBlockingObservable() sparingly. 5. cache() is my favorite operator. <3
22. #JavaSkop · stojan.me · RxAndroid 22 Take Away • Observables are processes that emit data. • Observers use the data. • Subscriptions are what links Observables with Observers. • subscribeOn() to change execution Scheduler. • observeOn() to change observation Scheduler.
23. #JavaSkop · stojan.me · RxAndroid 23 Questions? icon by Nathan Thompson, under CC-BY https://thenounproject.com/waymanate/