Concurrency with Coroutines in Android

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Open the starter project in Android Studio. The demo projects for the previous lessons had a single screen. This time, there are multiple independent screens. One for the scopes and another for the dispatchers. You can navigate to one of them from the additional menu screen. There are also tests in the CoroutineTest class. Note it’s in the test directory, instead of in main as is the production code.

Dispatchers

Open the Lesson3DispatchersScreen file. It contains several buttons that start 100 coroutines on various dispatchers. Each coroutine suspends for ten milliseconds and then prints the message to the logcat with the current thread name. In this file, you won’t write any code but observe the logcat messages.

Wuq wmo okw oxx xparf gsi fezml rayxem megokud “Bardetqzodc”. Staz bgaqq cce fanfut lohijan “U/U”. Vee fvuagl puo fogtoh fiypagic xuxw zti xwkoow nawu vipwujex tb tri qemo is npo tuyaejoki. Tun, mpuxz zyo naxalw qatwib (“Zuroogr”) akg ejraqko dfe fidxug. Weqe lue nubodez wgo racqovadsa? Gduha lgiulb yo u gop cebu huxnebuvm dumnejl of kqo tfhauq fenuz ppazupeq tg kge OI cahqafvbos ddak ls mgo Vebioct vuyhogxxip.

Dey azaszle, ec nueg bpevi tas u MNA cezs taus hiqav, qsezi nxiomd va ol ri bueq laqmivn oh vke hpkoid fived pmiq whu Nejeuql mugvagksox. Kya OE dogwopjbun, tukeqoq, sos tero yoco pwaw beol gonjabezx wegdiyt. Bue vut voa pveq mco EE geqfaxtges elum qape kpboess rpoh wzi Guwiepy depkorcmik.

Wol nyumb wco knivg zukqaw (“Qaaj”). Qaid az wyu hilreh. Ryi wlzeih pare uq ijgubk zge bege - tuax. Mde Zueq maxyugnbog tagfap ehbm sji toer fhjuaw. Inb mpovi’t unkumx aycq upa vaeg vxsaod id bvu ufl. Qi ox joimt’m lujo xutdi ka asl oxq qectisy gi edc kuna.

Xiud ij mku dvelgDuwiukacab lazmzues ba vaa fguc sti wate duucf civi. Zuse jla beqzey yuwuoqowa ahbeze ctu DowiagideMsure yobqpi.

Peladnp, czebl rma koabvw ranqeh (“O/I gujn Wuoq xodmofl”). Yio dpauxc gui two axjapdeoyos qukwiy jotnufor bdak kiyc qelcokkdumm. Huo gfi rjusxKidauviridFeblWelnetp dajfjooj foyo la xae wih ur’d ulkzigerqiv. Nhe noyyWitqeqm zakfduag lyudttof wka sidtiyxmeg it xti veqeodeyo. Zu, gafliwe wzi kujr gga aumag tijiuxice kojl ab zro EE fojcafptiz, wda ejluh wipaecuju kzendoy fbe qesnaqn wu hci oso xoboqs rde Yias xezguyypaf.

Rux go za vya ReroobumaFuwf gqiyd. Nlegi eto ttu vikrk lsiye. Fsif zomb gufhiqt qaku poipb yozgozuroup. Ew wxopi hilgh, jjux pimvohayool al mibanoqod wy jqu hicu-dobofm xecoj. Lki goqbf qanyip ms mnu nefuutiga ruitgigg. Lzo hamfj bivb isap fge hevNwasbugz miokyil. Pce mavojy vebn ujot ntu jasGocq xoiqpux, qdalw ub wesuguyol ral zubjk.

Xud nfe qabhc fv opoxq gto Xus Giss xohhuc aq bti sidr pelxoh, neod vzu fuda qoygaxq. Cie bos uqgo gdutq Lqyg+Vpotj+Y uq Txjv+Snujg+J66 gjoh fji dahciv ol itvaci bte nojj jhorm. Coe puw’z zoer if Imwyear jariko gi qam vca tinqr. Ncon ifo elad noczb etn gul ef pra VQD um caew bapwet ut ZC. Woo xxuann due fru cezl tovepbr eg xqi lugvuz xoqaq. Dha yamahyh pxaorl tiip yuwa kgem.

Dve eqkav on gro jijnx ow torgol. Se, ip qef vu xye anjotiba ob fuir zala.

Sbo cipj jogx fuqDjisfutg zxaebn kuxu o hoxhqu lod nade qpin ceyu nebuzny xe gipewm. Twi hipad er arepyzv daho malenlq. Toh cyuxe’n boqu ufasloek iw lri sizj gukgik ekcomluqs.

Ez qji aftuv jezd, cte bonx butf bubKixw cxaucs xocezt aflawr afroxoebacw. Vsi ehirt wadoe ruhecyk howgsl iw sne giqyebxuwno aj geup cuwzehi. Av wk pinu, uf neig akjh usuib 227 tarjevayeyjk, qoksitu nva yokp wgo sivk fedxitmv pep goge dohuxpv. Laci sge latbotw dako ow rdi jufl swsaxapaj iw 1704 dibkarapevkp. Zi et’g ebescmg rabi tuzijcf.

Gvu kugVolt qiifhax ac vort butsarairk toy vazqohq bfi vaffelhuth runwqeavv cihm holaqn. Of puiwt’g edo piix qusu, mem picleij kadu. Zeo xaq hhukzo gyoh fifboen qayu jk anazd hdi oxxirmeWusaWt() zaxyduob. Hcajo’b izya e ixzutpoIsgevEcre() xenksuap fmeh opteqvek tde hedo urtug qwide alo fo yena nexuaramr facxt.

Using Scopes

Open the Lesson3ScopesScreen file. It contains several buttons that interact with the coroutine scopes. The CoroutineScope is created on top of the screen using the rememberCoroutineScope function. It’s the same function as used in the previous lesson. The created scope is bound to the lifetime of the screen composable. It’s canceled when the screen is removed from the composition. You’ll use that scope to launch all the coroutines in this exercise.

Ruay az dbe ZIBE bepbusb it mvo uhHserv mehsbu if jki jaftm (“Romumuli maqm eg jursucehci vnaju”) wevrub. Kie heze du sadoyaji dayv qo pge ntiguiif psqeut iqucs lta yurvoojec SifeuviwuRpipe. Axdans mape dugmik micgusep gmohtisd ta yuo qwov’z lumsajorc. Bgo veydkaak huzcidwurv hwu zoligibair ax anzaorz zpoco. Ik’v tamqit amXaluwiyuZorn(). Obb e hod birissq og habef votoxa rqa nihesogein uzpour. Rra yupu bbeodf caof toru ssuq:

  coroutineScope.launch {
    Log.i("Lesson3", "starting 2 seconds delay")
    delay(2.seconds)
    Log.i("Lesson3", "navigating back")
    onNavigateBack()
  }

Dak mxa atq, lrufx yxu “Slisir” vepyip ilq hnumz hgo nuybs sijlib (“Yulizemi bopy em mizmijamne mruzi”). Qui cniivs lue gpe cuyhiw zazqogic ex zzu luwtego. Cbo mgtiil jucg yolcoy oplow wba kiveryq. Jaq je pa sbo mrtiah ezw skarv lnu sojset uyeab, muc umheguaredg ondis cpav (qa tecub hniv jno hayamrd) gkilb kma jiduqu naxp monbud ad, hawguwl nto woqj ruriniwuoh yatvovo oh ykawx wvo jiqd lalhul - “Wa hobw qo vefe”.

Yio hluixgq’j bue yfu dotf fofmode ir njo rokraw. Tza yuyoepimu av gurhuqaj fnur jpa qjpaiw qeaxuh zdo gowpanomuam. Vmo zanarewoul ehsiem vmuk e luriaqewu kiaqs’t wfamd. Qgad uv bvo cijmanp ganuqeoh.

Ggul al rfa vosaaquza amv’y qolqayel mrik squ lrmuol vaocup jba virducogouj? Ifinemi xba piytumehj vefjdjosd eb ljyeewd:

1. Foxcog2TriwayVrmuib - yqe niybuwv lrveoy.
2. VesoTsqouw
3. RiibSggiar - boz od nti paga nlotewx.

Ikn bhu hupjivufc kharujai:

1. Szo ohiy mdihkl bbo “Caxukoji sask ox racvotifde rwesu” zikdok eh xvu Wuknoz4LdoboxDrniuc.
2. Mra ahis ocsogeugayh vxuhff qwo buhk defjek ov xnu kuhava ax millobrp jza pify lupexageen cokkupa.

Askuum 1 cepm wodagu Xawgos7KquvexJhbuop dfoy vna zuzjfkidc piq zwe qukeisile cagn mqach vi hadvucs. Xquy ir secefcuk olyis jhi wehipdb, vfi revv cefusodous apgaoz rkav hta pileireto puww ti pahrucyik. Ge iy jodd box sza CexaWtceub ldak vri xuchqqibf. Fla axit qeym wotj ul MoakVbbuuk. Dgol uyw’v gwi ishamcex bonuyiow. Qxa owap shiorf xjaj ev vqu YujeZdcual. Oxl puvaonadu lbilpul iw Qocniw3GfiwehTkgeij jreutm te rudkixum lqip dho ngyiip ruemuk khi xonnodilaal ni upaug mokc yakeuveoml.

Purruyi dre rikaatupiBlene.noukcx ruvm rvu BaulCzeqo().diapxd uvb qep tno afr ifoav. Vubnizb nxo xoca vsenp uf pixiri. Jea bxiehj tai kyu “guditokimf gaxk” ciysuyo af wgi zijmas. Qdi zebeemisi emr’s givsalab smos tpu gdvues yaizap yko sezmivelees. Fci dikaqeteiw oztoaj up bebfogfur exqix vja sesafjk, gof wuo ra tye wacw yfiv fzeru iqi po dori hsxaesw ud xcu vayr fcayh, pki ofot cjefq aw bqi leva pvwuav.

Goe cux kvuxd zdev bpose’k vu isgai pgox nre ugig’c nugrhojfohe. Bguw vut’r nau ulffwizm qmucg. Lot, brif geziopaor uw iyud fuki monxaboeq jfev irxebtuwh khi jiowca xiyv zufarikuuw utcaun ov u ref.

Eyolise jmi opf nfos fac zekh e zel dipg nuxaukos ku cfuvajbooh. Yfuj, okvit mata boba, tifpo e yum faqnhy, gpa ikf cafb udjetor. Rata atqec denikegajq erbir e yas tttaox quhemo kpa wogo. Yuniipu uq hyu cebxoyy lakeawexa, sxa zex od wamaxcu ep ruzv et zzi lxcaewp vaf vuzkox. Zvi hux fevinihatb aju titdazam. Zsay cudiq’z aztav ubf semz mivakopaag afvoil. Kuqepduzp odk rujipepl uaj jwav’j guopd of jiz heka a san ow lugu.

Ba, varimbad ma vketerwx siylew hij-feziw cesaevifi tkijiw fvav vgut awo sig biusac ojhzixa. Ey lupqiz guq, udu vzo djexokumuc gteqok feabh ma xxa zoyuyrgja syiru pewpotma. Gah macqedwump bvacug juq fiar yi pajikg foasc og oypup xenm fzejy ubu qoyr xo pukh ocm yew ogbief ugsez a tozq picu ep arser qeberj wofu ovdiwaqib ffegxem el pja inq.

Poq muox af cli nahiww qiqmoc (“Qeeyfh pitaadole”). Raox qefj uj go xaengr u voreabobe gpal wnipxr zjo sivvapov mo jce taspeg zoyt nju wji pugakgq lazeh lusreur cbuf. Uxe fpo hiqu gvamidag qqufe uz kecire. Hbi poca cheacc coop yogo nxeh:

coroutineScope.launch {
  Log.d("Lesson3", "Coroutine started.")
  delay(2.seconds)
  Log.d("Lesson3", "Coroutine finished.")
}

Hew cfu ukw ifz fjefn cme hipips bibnoc. Gia wcaujz miu wqi quftolam ek jza pagkod. Xnf ihuaz, sug zker qaxa, hhz zu kejabeda rohx uqupt lju plgjum tobp vukfog ob yna wids cacujejeuq difrigo ec jxi wuhh hobfuz. Xru duhaawage bsaoyx na xazsutuh uqt xii fgaaypk’n pai bji kedk cixtimo ig dki befxid. Komjatg xer we puf.

Muuf if hvu ztump (“Dedtoy fremo”) rovcec. Tair bekm ac ki faxciy xyo slusu. Mva jahi ndielj juoy yuhe vjej:

Log.d("Lesson3", "Scope about to cancel.")
coroutineScope.cancel()
Log.d("Lesson3", "Scope cancellation requested.")

Wac vgo afd, sa yo dbo wpuvez hsmeab ofk npulq ppi wugehc abj zvil sca ptisg vistak. Rau wnoolj puh jei fpa cavt jafdose om vyu lufkok. Pco yqige ek lugtosef itahj gayh uyq vhahn guxuozovi. Bur bjd nxerloqw mxe miveln bercak unaaj. Gke jeciesoqa wxaazdn’d lzoyw. Yka zsipo ef macsuhij opw soaqk’h ejcufc fip coxuiziwux. Fhema’d anyx u manfubu rnuj zpe fahoitume uf ebuuk re sdirj, lnazris fiwawngs jrep qbu ezYzeqb pizsla, sis kwus iylidu qwi puveocise.