RxJava2 and Dagger2

Introduction to Reactive Programming and Dagger Kaushal Dhruw @drulabs (twitter,
GitHub, medium)

Copyright © 2016 Talentica Software (I) Pvt Ltd. All rights
reserved. Contents • MVP brief intro • Reactive programming • Retrofit with RxJava2 • Room with RxJava2 • Dependency injection & Dagger • Putting it all together 2

reserved. What’s NOT covered x Room x Retrofit x Advanced concepts x Testing x MVP, MVVM from scratch x Step by step walk through x In-depth knowledge of RxJava2 and Dagger2 3

reserved. MVP architectural pattern

reserved. Quiz App (walkthrough video)

Reactive Programming

reserved. Reactive programming • Wikipedia – It is an asynchronous programming paradigm concerned with data flows and propagation of change. • In other words: – Reactive programming is programming with asynchronous data streams.

reserved. Reactive programming is… Observer pattern Iterator pattern Functional support And more…

reserved. Reactive programming is… Observer pattern Iterator pattern Functional support Concurrency Resilience And more…

reserved. Reactive programming Observer pattern Iterator pattern Functional support

reserved. Reactive programming Observer pattern Functional support Iterator pattern

reserved. Reactive programming Observer pattern Iterator pattern Functional support Create Combine Transform Chain Listen Filter Reduce Map

reserved. Reactive Extensions (Rx) • Reactive extensions (or Rx) is a library for composing asynchronous and event-based programs by using observable sequences

reserved. Reactive Extensions (Rx) • Reactive extensions (or Rx) is a library for composing and programs by using sequences simultaneous operations. perform some operation(s) when event is triggered or received. think of it as asynchronous immutable array.

reserved. Reactive Extensions (Rx)

reserved. RxJava & RxAndroid • RxJava is a Java VM implementation of ReactiveX. • RxAndroid provides android specific bindings and extensions. So RxJava can be used in android applications

Reactive Programming Components

reserved. Components • Source (emits data) – Emits data streams • Subscriber (the observer or consumer) – Consumes data emitted from source • Scheduler (threads and concurrency) – Where to process and consume data

reserved. Components Source (observable) Subscriber (observer) Scheduler (concurrency) subscribe dispose Time onNext(1) onNext(2) Error / complete onNext(3)

reserved. Source Source (observable) Time onNext(1) onNext(2) Error / complete onNext(3)

reserved. Source & Subscriber Source (observable) Time onNext(1) onNext(2) Error / complete onNext(3) Subscriber (observer) subscribe dispose

reserved. Schedulers Source (observable) Time Subscriber (observer) Scheduler (concurrency) Thread t = new Thread(…); t.start(); Wait() Notify()

reserved. Schedulers Source (observable) Time Subscriber (observer) Scheduler (concurrency)

reserved. Schedulers Source (observable) Time Subscriber (observer) Scheduler (concurrency) • io() • computation() • newThread() • from(Executer)

reserved. Source, Subscriber & Scheduler Source (observable) Time onNext(1) onNext(2) Error / complete onNext(3) Subscriber (observer) subscribe dispose Scheduler (concurrency)

reserved. Components Source (observable) Subscriber (observer) Scheduler (concurrency) subscribe dispose Time onNext(1) onNext(2) Error / complete onNext(3)

reserved. Source • Observable<T> • Flowable<T> • Single<T> • Maybe<T> • Completable<T> • ObservableSource<T> • Publisher<T> • SingleSource<T> • MaybeSource<T> • CompletableSource<T>

reserved. Observable • Observable<T> • Flowable<T> • Single<T> • Maybe<T> • Completable<T> Emits 0 to N items terminates with success or exception

reserved. Flowable • Observable<T> • Flowable<T> • Single<T> • Maybe<T> • Completable<T> Emits 0 to N items terminates with success or exception. Supports backpressure

reserved. Single • Observable<T> • Flowable<T> • Single<T> • Maybe<T> • Completable<T> Emits single item or error. Has no completion indicator

reserved. Maybe • Observable<T> • Flowable<T> • Single<T> • Maybe<T> • Completable<T> Succeeds with 0 or 1 item, or fails. Has completion indicator. Reactive optional.

reserved. Completable • Observable<T> • Flowable<T> • Single<T> • Maybe<T> • Completable<T> Completes with success or fails. No emission.

reserved. RxJava Operators • Creational – Create – Just – From • Transformational – Map – Flatmap – Group by • Filter – Filter – Distinct – Skip • Combine – Concat – Merge – Zip

reserved. Rx Marbles Interactive diagram of Rx Observables

reserved. Operator chaining Map Filter Merge

reserved. Operator chaining Filter Reduce

reserved. Retrofit with RxJava2 Add retrofit RxJava2 adapter dependency And of course RxAndroid dependency

reserved. Retrofit with RxJava Use RxJava2 with retrofit

reserved. Room & RxJava Add Room and RxJava support dependency Supports Flowable, Single and Maybe

reserved. Room & RxJava Supports Flowable, Single and Maybe Regular RxJava2 RxJava2 ????? ?????

Dependency injection Dagger2

reserved. Dependency injection Got all the ingredients for pizza except the base Should I create pizza base myself? You are gonna mess it up let me do it

reserved. Dependency injection Think in terms of objects Avoid this

reserved. Dependency injection Get dependencies from outside Injecting the dependency

reserved. Dependency injection Instead of having hidden dependencies, pass the dependent objects • loose coupling • Testable code • Reusable code • Readable code • Enforces SRP

reserved. Dagger2 Dagger is a compile time dependency injection framework for both Java and Android. I will inject the dependencies just tell me: • What dependencies to inject - @Component • How to create it - @Module, @Provides • Where to inject - @Inject • Which one to inject - @Qualifier, @Named

reserved. Dagger dependency graph Pizza Pizza base Chicken sausage Cheese Flour Chicken Milk salt Processed chicken Toppings Tomato chilli ﬂakes oregano

reserved. Types of injection • Field injection • Constructor injection • Method injection

Dagger code and demo

reserved. Summary • Brief introduction of MVP • Reactive programming – What, why and how? – Various operators – With Room and Retrofit • Dagger • How these work together

reserved. Thank you Kaushal Dhruw @drulabs (twitter, medium, github) Q & A

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RxJava2 and Dagger2

RxJava2 and Dagger2

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