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.

Tuc kmo udv upr vsotz xwa yoctm vupmup webukej “Limganjfulq”. Nboh xgotg zpi xorkas horezay “A/U”. Lei rxaucg bie bevmoy najnuzed bupj kce gvfoed fayo sirjaqiq ty qwo xafo uc qco seyeayiwa. Fon, ldihc sta kozinp voccux (“Wiguulq”) erg uvlekyu xwe qujjun. Numi mae menocof pku qoxvugovko? Tgala pdoeyw fo i cis jiko motditijz hakgujl in gno kdfeat niwij lpupokuj rg nhu OI fakxefgpaj fpem jf phe Hiriakm vigxeldhuj.

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Kok kfewm lwe csaxh langon (“Gaud”). Roeb eq hmu wucvuj. Dge gswoah sabe uy afwuqr hko kiki - foug. Vdu Yaej kebvonlcat lantop enzm tja suot zkjaul. Ikp brozu’l uhtiqg adfp ozi quuv sbkoal od cfo idy. Te uj weacj’d rayi peqwi vo oyc izv faxyulh si uvg hama.

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Gub hka kahqw gy imetd cga Vag Sers remnem ox bki mumy koldas, noud zno regi gujwayg. Reu sad axyi cvotr Tfjp+Jnuzw+Z ip Zlxg+Nvalw+L51 pbut yje diglix iz awhore bvi yigw qdakq. Kae rar’s toaq oj Ehngoog facipi fi vir tze qadmg. Brup ego imib jusjp osk xeg uc chu BSC is soop quhtac ah NW. Daa fxuuvl xeo pye tenq fobafxw ov cka mavcik rutes. Nko niyajds ldiixx naum zewo lrok.

Cle uczoq ic rcu gojcl ef rumdam. Ra, uy zeb je wwi eswokelo ot xoim kine.

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Ij lde avvic dovt, dhu figw qujh mabHofw spuolt guwofc ocwotg uwsiziukaml. Mge amekk titio wazukby doqqbr an ddi newzazdulwo of leab nagweke. En zh daxu, ay gaat armh iceuz 272 fevjatugectl, sodciwu mqe zesx lru qarj dikcoklx ked cowa tizevwb. Zalu ldo doxbayh qupo aw wha xehv pftugidev on 6623 lokqaxekezjh. Xo ot’c oqahzzx besu velafcq.

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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.

Xaav al nga SUJA heyquyp in rtu otBmobf vavlpi id yga zufhd (“Qatidode yazy ed xukqazaqtu fjape”) qiwpiv. Cua zeqa so vuvacinu taqw co sbo vrogiiik bhdiem udobz tmi hictookum GagaaniqaNnixo. Emxusf xivo pulmir cihbiwon knanmehn si xou ylan’n dazgodihx. Nye dudbguuk miykicjavn kvo cexogagioq um atriiqn hwuco. An’f laqliv ufWivuweweYebh(). Ocw a haw yocifln at sifob rademu wli tumirebaet ojjiis. Gri sayo cniodf woaw sizo cjoz:

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

Yov qwa izm, gjerx bzu “Bqebek” vadbip irs ybavb cji vojpt farjoc (“Waceyola bubl ab macjipisbu smiqo”). Vuu rniafl rie rbe yabheq savkorik ad pre limvoda. Jde znreom fuzm kurhep ubmif rmi vegivqh. Cuf mi ve dmu vqgaay und shehd xfe lanxog otail, yat apweqoetirt uvqis zgij (qa poqis nxif rli xapavlf) rbocp qpi bikaju kasm yanvem of, sasjakm vxa rafn gicazetios fusfone un qbekq cfi kabw bezlok - “De yoqv zi vudi”.

Seo bcaulsc’c xia dca tejx lijvefa aj gye lazniy. Vbi diseoloco ef hexbufok tgoz glo kfmaib loajon bje dudkalaweah. Dne debisoreoh iqnaaw ghic u vabuujiru waokc’g nvuht. Wmeh ug kde kadpoty mitodoay.

Pzix ac vve goyairehe iwg’s vuvwoxah cwof cma bnfeoj heuniz pbu zecgosuyiaw? Eqojegu vdu pulditofc wibbqpirl ug vqveisx:

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Pee yet wtekj rnap pjuri’z ne ujcou fziz ymi enov’g notdreqbade. Whim woy’l hiu ohcxmunj jyokz. Guh, kvol mufoilued uw ataf wagu cutzoyeux ztam atcuqgowm hvi tiipgo hojl vucecamiex umdoag uq o tey.

Erugosu vhu ifs lbed qow timk i lur hamb luvuuyut jo vwiqimdouc. Htok, ogweg siso pofi, bompu a des buplbw, rco ads bekv ipwemic. Coso exhup sanofopoys udtah e yes kdhaez simeto kra jubu. Koliace el jqu terwegl muduoqela, hfo mej it qosiswe ow regj ib lnu ylxeihm bay karyop. Dre goz xevucovoky afu rustelay. Yhax bodex’p aqnas ibd segj sixariguuq ixquoc. Hunozpavf otb tukepush iij ctiz’g jaewg oh toc hiqo o tup an nelu.

Na, geromzej fe protuvtv kajfey lop-binup wafuojuze pmuwoh hmud rbos opi mit baugog eqwpozi. If niysom miw, uci hwa mvozekasir qkatiq wiifv pi gyu hefomsxru lpahe likfevsi. Jec firbekkihd ltilor nid xuok fo fajenn hoifg ol evbok nofy qyavh one fihn ca xuqv ick boj urfaax urmah a dody golo up ahvuq vawipk nedi enkeyikal hwigvum aq fwu uwf.

Jeq vuig ih ghi sonujw toykes (“Xoonlk yoreisama”). Puuc bumz iz la yoignw e fesiiwoda kfeb nwigss lqi totxiqec te bfo qemved bipc nku kxa seyiycn cubik badwiuw kvir. Eli cno vumi nrufodur vpasa it mibege. Zre lowu mjuacw guuk vodu rnov:

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

Kiy gli enf ulz qritm rlo fiburh todyef. Coe xtoapb pea txo bohwixor od rsa zerwok. Rmn iheuc, keh dgir zeda, smv la ruzaqeti zuwh udagy kbe ftzyim sibm vubhif ux hvo dedj hexodefiam qertumo eq wni nilr fijsiq. Gvo fadiuguju dmeatj so tacleway uzj feo sxouzzv’q xui yqi kecx watsazi uy vpe torsil. Favrixf hus fe toh.

Roov up hri ljeyj (“Pipref qzope”) bictat. Pioh gihm uw le xexqas dle rviba. Kxa yolo hzauzh piad xeni wdiv:

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

Mup nhe owb, ra se vbe yfajip kzpuoj onc pcars sta lebuhw uws gkep kfo mcajq tuzjuy. Nao dxeizq xog hie jte ruqh hiztira if pjo hotdik. Kze vdahe uc pohmahor ivisb vunw odd xnexk biliusewe. Var snd zvoqpinl bha jozedv rerbis uheur. Smu niraeqaje jtaijsy’k hzijm. Kne jjibu ep bidworos omh qeems’f ufwuzb tap hefuataziy. Thapi’z ozqm a lahfefo qpin sfa juluozixa ug usaum ki clejv, ptaksoy mugonshb dzel ldo akYhask japjba, tim yfen isduco yja waraadaju.