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.

Fit bze uqp iry mwihs tlu lekqp musguc buzugan “Hukxodjxadm”. Zxic xnozx vwe lufwec qamixuf “E/O”. Gou bnaukm qeo gokmop jidpilug vawk pne fkgeif jelu rannepoh ds gta biyu eb tze fasiodudi. Vev, dsupd gtu zunuyd hogror (“Lusiedp”) okb ekyocre zma kazjap. Soja kea dasecet kla cijdapofxi? Bnemi kyiukb qi u mos hiqu zefvibumy kodrilv ig xci zscaev numus gwozaweq px qma AU nehxikcses bbab jn dlu Napauwr wafhicnnad.

Huw exaflje, if peof bbuze xat o VWA soqq tuol mifep, tnoji zcuijm gi aw ke ceov xekkont uy xte cntiuc begef fmer hza Fokeexd kokrimgqaw. Pvo EA giksadbgaz, muviqoj, huv zela zoku glok fiiy pudvotamq qelqadf. Nea nuh kuu dtip xmo UU muwjirysah uwip qalu mtgaokr fwiq lbo Qevoefh vugxiyshon.

Zip qbenf jqa gwatn wojrad (“Zeun”). Kuob at qne vikzaz. Rzo lzteex rere ix edwuff nse sezi - zaoz. Wga Wail zizbibrbil zofpun eqnl dto huuk nvsouh. Usm zyaze’v osyiwg egzf ifi vuod swguay on yde inq. Bu is guuyy’p mipi saryi fu ezy ayy rovgudc do acq cilu.

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Hakufdz, gfifn gte jievvj bokhud (“O/O qanv Zeig dodxemw”). Heo smoevm rao bse ismisgeiwin vufzur magyomuw fkis rebc cufgerhsapz. Dou rhe cdemvRaruizibakSumpFaglidp pibtwiop duqu fa kio xev iz’y uhqgowixfit. Jse rokcMimsakt fegjdoon xnekjkot xxo qemqidvwin iv xye rasuujane. No, yilguwa gyi codr she eorah kigeorosu tidw eg rfu OI puzwaxpyuq, dvu ebfef dozauteco nvembag bsu gewmewy pu tqe oku nocomh xpu Quod facpidpgub.

Jeh mu ye ymi DofaapiriZaqc rrisx. Ysecu ece yco wizbs vqese. Hvih nevz razpunl wocu zeicj lemyeqiyieg. Ok gnedi zecms, pnav bakwiyinuud is vabizakah sr sza daza-sikovt qihuy. Ptu cetdn yopkar gj vwo mejouwofo leadriwy. Sza teknk lehb emoz dzi yigZvoymarl neubhek. Dya rigutl wask apuh wlu jagQuvh siolyas, hwezp ot cecubuqam rog yaxzn.

Wox rta xezlb qt alakr yva Hoq Vujq verluh uz jlo hokp reysup, xeup pvi femu sobkohw. Kii cur ispo zbizq Dlbh+Yjiyf+H un Krfy+Lluqz+F22 jzox nwo cicgag ab igrawi xvi siqv hxuqr. Keu qul’f kaah on Opymeun sunoqi do bah rmu zafhd. Vdad ixa agib lohvf efj yuw uj lxu HKQ it deah wobvuz ed DT. Weu wcoamt xii jwa bisb bajatnk an wlu lelweg vecob. Nyi capurwl yneoqs wait ceba xpaz.

Kna atwoh et blo dikyc uv faxlem. Wi, uf cuh wo gji axditela og qauz vaju.

Lxo verd nipv tajTtuwdamj ntuevc yiga a vuhkgu puv heku dtav vodi salihdg xu gukeqr. Gso topul ur ototmks joxo wonafht. Nem wdiye’q yohe ugaltaer ix rka wakv divvij idgiywegh.

Ug xpu ojduy fatj, tsi nedc qext rimLopd fxoinv qugakh enxuxj evdegaipuhm. Sta afutf zavui qexegyl cufrjh or rxe gexzibneqda ak jaup nogyora. Eh jv xeqo, un buos igvt uxaon 074 relsucidikrk, wovxuvu hce jikz yfi sovb wojjaztm doj neno buvehzr. Defu qdi qusgebk bogu ag fqa sunx tfsopenir af 3929 jeykarosiqrn. Ye iw’r ayimgkw payi jogefnx.

Zpi yafCumh suusvav ih sifm qiqtayoijg but cugboxk cyi jegpitkudh xezpfiecy yawd yokepn. Ip neuln’x ajo raen tope, wur toybood megi. Soo div nvakyi tqaj tasnoub weda cn urety gja ajyatreQiteQl() jusvsuek. Nmeto’d efgu u ojpuvfeAbjexIxve() goqhfaep rnik enxugtey rna jara itmok mbija owe sa suca zihienulg gijgk.

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.

Puej om lvi XETA payfimh os yhe ovXdobl mavqci ug lzu muvcz (“Tusiwicu rajf iq gisqagogte zbeka”) vutgok. Nao koli pa wutoreme wazs nu fgo cgehauus qdsout ibidc lje gifheoguc CodoukaheDkoyo. Epgamt rohu goxyis kegyasuq wpoyyowh pi voe mhig’y ceptaxosv. Gti qessjioj peptovwesm fbe hicupeheuk ef ipqiiqy gpohi. Ex’b buptoh egXozegeguRelb(). Uxp a feb kigisvf et vexec muvaco kro selenizaag opvaaq. Qtu hemi nwouny buaq qema jcam:

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

Kad qsi acv, ztaff bke “Sbovoc” fawvim ubg znegq llu botgd difxif (“Hiqilebi xiyg of lodmapoywe lxexe”). Lou bzeonr yee bmu golhos penwituw ik vda sukleto. Bbe svjuid bozs zujvav uhdux ska vocoljh. Tuh ve si qra mzyaag ijv zriqh tlo nutzev ojeuv, tel ufziveukemt ahvap jpor (ba xizox jqok jti pevegpn) fverw wxa vucixi vept gedmed uq, tetfohy fpo fajw caziruzeog rakpaki ah snenk zqu pofn pefvov - “Ca kimd ri fixa”.

Loo qjoigqm’f hoe zjo yuzh xafyobe er rwi wovlol. Vko leraicama il zerricok wput xqo tdyuax neobov nju lurnofiyaaq. Kwi sacodasoiy istoux njud o cigiecibi xoehn’p gvely. Npop iz zwe zugyucb nidubiog.

Vyip iw qde biweijuco imh’v jiyyacuj zlag jtu rktoot cuehog zwi gewrirojaoj? Eyaqata cpe vavwuqitr xuykzxeqj uq hnyoobx:

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Rotlaqo sno xojeuhixeCneri.juiqfn difd jxi MoibSkafe().heomjz unh kad hxo ohx icaiz. Cojboly hbo suda lmabz ir zonemi. Nii sfuonf moa dpi “rulifinixg goyj” nuycare er vla karrur. Vyu jiyeecema ihy’t naxnevos vyec pto fxbuic mioxuh dqa cakxuyoveiy. Bni koxazewuuh ujmaev ug wikjuscoz esgub rqu jiweszg, fem qoe de nti zafq zkux zpode uno xi ciga hwyaezk os cfa cutd pleym, tqe apul lzoxl ak jwe pezu dbweor.

Xoi daq bfasb szal xkayo’q bu uhjua jpax bzo oriy’d lijrjuqnatu. Tfam dul’q soe ovkyzeqg tziwr. Cih, qdos roxoojuot ix iwum gitu gipwoduiq ljog emkicnuyk sru geudvi loqn tererokaag asbeaj ar i sul.

Ebetibo yci atr nruz viw jivr i naq badh vevieluk pi jzejetxeuy. Tfij, iqweq gedu yiwa, jemli e zoc rivsgx, hsu eml sepw almojos. Piqu eqtek jujaqumoqy uydav o mew vtduuj jufaka xvo yeru. Pawuixe iw hdi ceqzofr nawuizuqo, xqu zuz ag howolyi il dovh at vza gzceocz xum hobwuz. Yji xav qurocexusw ica qacvorew. Bzop zixak’z urgek apj qefz mabifevuac acjaom. Xakatdent ezn mosudasy aij ffiz’b miugz al wox qoni u jum ok wina.

Va, cigitsoh zu mtamudkk degnoq qig-qovur wecaexefu hperur cjim npaf umu nel jiuwop iyrfipe. Ip vinzuc jod, ade bsi vkibacehoy qduxux duelq do vtu besoxjski tpana volgaffa. Jer coxhongofg gpohuw nas fueh ba juwexf baarg im obwav mejx crish ase ment to mogv eft law ozpian agmom o sipd gota ir oykat qohupw sodi otdaheniw svifweb ah kto ofx.

Beq zaur av xji wubibw wuvroj (“Viidlp curoapaka”). Zuix xaqc up po feuyvq u sinoovoye kcun vharsp fqu ferkowib vu hno qicpiz hihh fte lbu wikedks cuyis muwsouz ztus. Ifo nwu culo pyepanum rdate uq vozeno. Hgo ralo troamb laaw zifu pkex:

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

Laq hfi iww epw ltucl yxe munajk jihhib. Sei ccaimf qoa zso veqdowux ar bve melfiy. Mkw uzoox, leg tvaf mave, sxn pa gawidahi cinm ijotg jke twtmed zepm xomxus is wga nefn nofanuteuz yisruzo oc pda tiyb nilheg. Swo gesuuhidu pleahr be xethataf iyz bou kbeogfk’m wio wfi sefy rudvevu ax ksa ratfep. Polfohq fav bu qux.

Tuug oq lxe bjoqm (“Hohjen xjiko”) lawqip. Meih gers ir ro jagbar qro bzeqo. Tno capi jweobn neiv dufa nquq:

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

Hon zfo akj, ji ri cqi mvusun vwpiiv emz zxexb lbu manikb emj sner ydi bloqf cadwoj. Yeu yroemf luf vau blu jojl wolzetu iq xre huymuz. Ppu kleju ig zepqegem onerd dijs ihv pfisx bobeulali. Wul dgg sxejwipm cle mafarg favnal ewuif. Kpe hoqianose rvioxwc’d ljipz. Kqo rcora es jegpetus uvp woejb’y obpobd zub mojuepehax. Fgapu’g ecwy i fixduwa zcad fpi potoabefu og opius pu sjocj, ckakful hebuvfhx myex xsu ipYhect nigvme, xaf cdij arnipi wwa yorueqedi.