RxJava in Baby Steps

a learning curve

a steep learning curve

you a steep learning curve

superstar a steep learning curve you

you superstar a steep learning curve

you superstar a steep learning curve me

RxJava in baby steps @brwngrldev

asynchronous data streams

GPS Updates Time

GPS Updates Time -36.34543, 3.23445

-36.34543, 3.23445

-36.24543, 3.23425

GPS Updates Time

-36.34543, 3.23445

-36.24543, 3.23425

-35.34543, 3.13445 GPS Updates Time

Time server response

i want toys!!! Time server response

Time server response toys

Time i want toys!!! server response

Time server response

Which of the following is an asynchronous data stream? A: click events B: database access C: server response D: all of the above

A: click events B: database access C: server response D: all of the above Which of the following is an asynchronous data stream?

scientific Research

scientific Research

Data Transformation Observable.just( 5 , 6 , 7 ) .map { ";-) " . repeat ( it ) }

.subscribe { println ( it ) }

Data Transformation Observable.just(5, 6, 7) .map { ";-) " . repeat ( it ) }

.subscribe { println ( it ) } ;-) ;-) ;-) ;-) ;-)
;-) ;-) ;-) ;-) ;-) ;-)
;-) ;-) ;-) ;-) ;-) ;-) ;-)

chaining Observable.just( 5 , 6 , 7 ) .map { ";-) " . repeat ( it ) }

.filter { it . length < 24 }

.subscribe { println ( it ) }

chaining ;-) ;-) ;-) ;-) ;-)
Observable.just(5, 6, 7) .map { ";-) " . repeat ( it ) }

.filter { it . length < 24 }

.subscribe { println ( it ) }

RxJava i s. . . ? A: the silver bullet B: simply magic C: pure voodoo D: a library

RxJava i s. . . ? A: the silver bullet B: simply magic C: pure voodoo D: a library

listOf ( 5 , 6 , 7 ) . map { it * 5 }

. filter { it

25 }

kotlin collections

listOf ( 5 , 6 , 7 ) . map { it * 5 }

. filter { it

25 }

kotlin collections 5 6 7

listOf ( 5 , 6 , 7 ) . map { it * 5 }

. filter { it

25 }

kotlin collections 5 6 7 map 25 30 35

listOf ( 5 , 6 , 7 ) . map { it * 5 }

. filter { it

25 }

kotlin collections 5 6 7 map 25 30 35 filter 30 35

listOf ( 5 , 6 , 7 ) . asSequence () . map { it * 5 }

. filter { it

25 }

. toList () kotlin sequences

kotlin sequences listOf ( 5 , 6 , 7 ) . asSequence () . map { it * 5 }

. filter { it

25 }

. toList () 5 6 7

5 6 7 map filter kotlin sequences 25 listOf ( 5 , 6 , 7 ) . asSequence () . map { it * 5 }

. filter { it

25 }

. toList ()

5 6 7 map filter kotlin sequences 25 30 30 listOf ( 5 , 6 , 7 ) . asSequence () . map { it * 5 }

. filter { it

25 }

. toList ()

5 6 7 map filter kotlin sequences 25 30 35 30 35 listOf ( 5 , 6 , 7 ) . asSequence () . map { it * 5 }

. filter { it

25 }

. toList ()

asynchronous data streams

RxJava numbers

.

map { it * 5 }

. filter { it

25 }

. subscribe ()

RxJava numbers

.

map { it * 5 }

. filter { it

25 }

. subscribe () 5 25 map filter

RxJava numbers

.

map { it * 5 }

. filter { it

25 }

. subscribe () 5 6 map filter 25 30 30

RxJava numbers

.

map { it * 5 }

. filter { it

25 }

. subscribe () 5 6 map filter 25 30 30 35 7 35 35

flexible threading

schedulers

Observable.just( 5 , 6 , 7 )

.map {

";-) " . repeat ( it ) }

.subscribe {

println ( it ) }

Observable.just( 5 , 6 , 7 )

    .

subscribeOn( Schedulers.io ())

.map {

";-) " . repeat ( it ) }

.subscribe {

println ( it ) }

The Basics observable

The Basics observable observer

The Basics operators observable observer

observable

hot observable Time

hot observable Time i want hugs!!!

hot observable Time hugs

hot observable Time hugs hugs

hot observable Time hugs hugs hugs

Cold observable Time

Cold observable Time

Cold observable Time

Cold observable Time hugs

Cold observable Time hugs hugs

Cold observable Time hugs hugs hugs

where?

Observable.create<Int> { subscriber

-> }

Observable.create<Int> { subscriber

-> }

Observable.just( item1 , item2 , item3 )

Observable.create<Int> { subscriber

-> }

Observable.just( item1 , item2 , item3 ) Observable .interval( 2 , TimeUnit. SECONDS )

Observable.create<Int> { subscriber ->

}

Observable.create<Int> { subscriber ->

Logger.log( "create" ) Logger.log( "complete" ) } Logger.log( "done" )

Observable.create<Int> { subscriber ->

Logger.log( "create" ) subscriber.onNext( 5 ) subscriber.onNext( 6 ) subscriber.onNext( 7 )

Logger.log( "complete" )

} Logger.log( "done" )

Observable.create<Int> { subscriber ->

Logger.log( "create" ) subscriber.onNext(5) subscriber.onNext(6) subscriber.onNext(7) subscriber.onComplete() Logger.log( "complete" ) } Logger.log( "done" )

A: emit items B: be cold C: be hot D: all of the above Observables ca n. . .

A: emit items B: be cold C: be hot D: all of the above Observables ca n. . .

observer

interface Observer<T

{

fun onError(e: Throwable)

fun onComplete()

fun onNext(t: T )

fun onSubscribe(d: Disposable) }

interface Observer<T

{

fun onError(e: Throwable)

fun onComplete()

fun onNext(t: T )

fun onSubscribe(d: Disposable) }

interface Observer<T

{

fun onError(e: Throwable)

fun onComplete()

fun onNext(t: T )

fun onSubscribe(d: Disposable) }

interface Observer<T

{

fun onError(e: Throwable)

fun onComplete()

fun onNext(t: T )

fun onSubscribe(d: Disposable) }

interface Observer<T

{

fun onError(e: Throwable)

fun onComplete()

fun onNext(t: T )

fun onSubscribe(d: Disposable) }

observer’s lifecycle onSubscribe

observer’s lifecycle onNext Normal flow onSubscribe

observer’s lifecycle onComplete Normal flow onSubscribe onNext

observer’s lifecycle onComplete onError Normal flow onSubscribe onNext

val observer = object : Observer<Int> {

override fun onError(e: Throwable) { Logger.log(e) }

override fun onComplete() { Logger.log( "on complete" ) }

override fun onNext(t: Int) { Logger.log( "next: $ t " ) }

override fun onSubscribe(d: Disposable) { Logger.log( "on subscribe" ) } }

interface Consumer<T

{

fun accept(t: T ) }

val consumer = object : Consumer<Int> {

override fun accept(t: Int) { Logger.log( "next: $ t " ) }

}

val consumer = Consumer <Int> { t -> Logger.log( "next: $ t " ) } obs.subscribe(consumer) consumer

obs.subscribe( Consumer <Int> { t -> Logger.log( "next: $ t " ) } ) consumer

obs.subscribe( { t -> Logger.log( "next: $ t " ) } ) consumer

obs.subscribe { t -> Logger.log( "next: $ t " ) }

consumer

obs.subscribe { Logger.log( "next: $it " ) }

consumer

A: have a lifecycle

B: always complete

C: Never Error

D: all of the above Observ ers. . .

Observ ers. . . A: have a lifecycle

B: always complete

C: Never Error

D: all of the above

operator

Time Operator: map()

Time Operator: map() :-) :-(

Time Operator: map() :-) :-) :-( :-(

Time Operator: map() :-) :-) :-) :-( :-( :-(

Time Operator: map() :-) :-) :-) :-) :-( :-( :-( :-(

Operator: map() Observable.just(5, 6, 7) .map { ";-) " . repeat ( it ) }

.subscribe { println ( it ) }

Operator: map() ;-) ;-) ;-) ;-) ;-)
;-) ;-) ;-) ;-) ;-) ;-)
;-) ;-) ;-) ;-) ;-) ;-) ;-) Observable.just(5, 6, 7) .map { ";-) " . repeat ( it ) }

.subscribe { println ( it ) }

Operator: map() Observable.just(5, 6, 7) .map( object : Function<Int, String> {

override fun apply(t: Int): String {

return ";-) " . repeat (t) } })

.subscribe 

{ println ( it ) }

Operator: map() Observable.just(5, 6, 7) .map( object : Function<Int, String> {

override fun apply(t: Int): String {

return ";-) " . repeat (t) } })

.subscribe 

{ println ( it ) }

Operator: map() Observable.just(5, 6, 7) .map( object : Function<Int, String> {

override fun apply(t: Int): String {

return ";-) " . repeat (t) } })

.subscribe 

{ println ( it ) }

Operator: map() Observable.just(5, 6, 7) .map( object : Function<Int, String> {

override fun apply(t: Int): String {

return ";-) " . repeat (t) } })

.subscribe 

{ println ( it ) }

    .map(

object : Function<Int, String> {

override fun apply(t: Int): String {

return ";-) " . repeat (t) } }) .map { ";-) " . repeat ( it ) }

what’s the output? Observable.just( 1, 2, 3 ) .map { it * 2

}

.subscribe { println ( it ) }

A: 1, 2, 3

B: a, b, c

C: 2, 4, 6

D: 6, 2, 4 Observable.just( 1, 2, 3 ) .map { it * 2

}

.subscribe { println ( it ) } what’s the output?

Observable.just(1, 2, 3 ) .map { it * 2

}

.subscribe { println ( it ) } A: 1, 2, 3

B: a, b, c

C: 2, 4, 6

D: 6, 2, 4 what’s the output?

what’s the output? Observable.just( 1, 2, 3 ) .map { it * 2

}

    .filter 

{ it < 6

}

.subscribe { println ( it ) }

A: 2, 3, 1

B: 2, 4 C: 1, 2, 3

D: 6, 4 what’s the output? Observable.just( 1, 2, 3 ) .map { it * 2

}

    .filter 

{ it < 6

}

.subscribe { println ( it ) }

what’s the output? Observable.just(1, 2, 3 ) .map { it * 2

}

    .filter 

{ it < 6

}

.subscribe { println ( it ) } A: 2, 3, 1

B: 2, 4 C: 1, 2, 3

D: 6, 4

Operator: flatmap() via reactivex.io

Operator: flatmap() via reactivex.io item

Operator: flatmap() via reactivex.io item observable

Operator: flatmap() Observable.just( ,
) .flatMap( { Observable.just( ) } )

.subscribe { println ( it ) } :-( :-(

time flatmap

time flatmap :-(

time flatmap :-(

time flatmap :-(

time flatmap :-( :-(

time flatmap :-( :-(

time flatmap :-( :-(

time flatmap :-( :-(

Long Running asynchronous

Operator: flatmap() val users // Observable<User>

Operator: flatmap() val users // Observable<User>

val posts: Observable<Post>

Operator: flatmap() val users // Observable<User> val posts: Observable<Post> posts = users.flatMap { getUsersPosts( it . id ) }

Operator: flatmap() val users // Observable<User> val posts: Observable<Post> posts = users.flatMap { getUsersPosts( it . id ) }

posts.subscribe { println ( it ) }

via reactivex.io

Flowable Maybe backpressure Disposable Single completable

should you use rxjava?

like functional programing? Process items asynchronously?

compose data? handle errors gracefully? should you use rxjava?

should you use rxjava? like functional programing? Process items asynchronously?

compose data? handle errors gracefully?

it depends

The Basics operators observable observer

you

www.adavis.info @brwngrldev

• Reactive Programming on Android with RxJava ( http://amzn.to/2yOAkxn )

• Reactive Programming with RxJava ( http://amzn.to/2zQtqb5 )

• RxJava Playlist (https://goo.gl/9fw1Zv)

• Learning RxJava for Android Devs (https://goo.gl/VWxFLK )

• RxJava Video Course ( https://caster.io/courses/rxjava ) resources

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