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5෼ͰΘ͔ͬͨؾʹͳΔKotlin Corou,nes @takuji31 ؼ͖ͬͯͨؔ੢ϞόΠϧΞϓϦݚڀձ #2

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ࣗݾ঺հ

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ࣗݾ঺հ • @takuji31 id:takuji31 • Takuji Nishibayashi • Hatena Co., Ltd. • App Team • ίϛοΫDAYS • δϟϯϓϧʔΩʔʂ • ΧΫϤϜ

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ࣗݾ঺հ • Android • Kotlin • Flu-er • ! h-ps:/ /blog.takuji31.jp • " h-ps:/ /nazuna.takuji31.jp • # $ h-ps:/ /photo.takuji31.jp

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Kotlin Corou+nes

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࢖ͬͯ·͔͢ʁ

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ίϧʔνϯʢӳ: co-rou(neʣͱ͸ϓϩάϥ ϛϯάͷߏ଄ͷҰछɻαϒϧʔνϯ͕Τϯτ Ϧʔ͔ΒϦλʔϯ·ͰΛҰͭͷॲཧ୯Ґͱ͢ Δͷʹର͠ɺίϧʔνϯ͸͍ͬͨΜॲཧΛ தஅͨ͠ޙɺଓ͖͔ΒॲཧΛ࠶։Ͱ͖Δɻ — h$ps://ja.wikipedia.org/wiki/ %E3%82%B3%E3%83%AB%E3%83%BC%E3%83%81%E3%83%B3

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Corou%neʹ͍͓ͭͯ͞Β͍͠· ͠ΐ͏

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suspended func*on

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தஅՄೳͳؔ਺

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suspend function fetchUser() : User { val user = // ωοτϫʔΫ௨৴ͳͲͷॏ͍ॲཧ return user }

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Corou%neContext

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Corou%neͷίϯςΩετ

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ෳ਺ͷElementΛ૊Έ߹Θͤͯ࡞Δ

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Job

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Dispatcher

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Name

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Excep&onHandler

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ωετՄೳ

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val context = Job() + Dispatchers.Main launch(context) { // run in main thread delay(100) val response = withContext(Dispatchers.Default) { // run in background thread networkAccess() } }

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Corou%neScope

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Corou%neͷείʔϓ

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ContextΛ࣋ͭ

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ωετՄೳ

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async/launchͰ্ཱͪ͛ͨίϧʔν ϯ಺Ͱྫ֎͕ى͖Δͱείʔϓશମ ͕ࢮ͵ͷͰ஫ҙ

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Ϋϥογϡ͢Δ΍ͭ // ྫ֎Ͱείʔϓશମ͕ࢮΜͰΫϥογϡ͢Δ coroutineScope { try { val user = async { fetchUser() } val series = async { fetchSeries("12345") } doSomething(user.await(), series.await()) } catch (e: IOException) { // catch͞Εͳ͍ } }

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ରࡦ coroutineScope { try { // Nested scope val (user, series) = coroutineScope { val user = async { fetchUser() } val series = async { fetchSeries("12345") } Pair(user, series) } doSomething(user.await(), series.await()) } catch (e: IOException) { // show error } }

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Deferred

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ϊϯϒϩοΩϯάͳFuture

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val user = async { fetchUser() } // Deferred val series = async { fetchSeries("12345") } // Deferred doSomething(user.await(), series.await())

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Channel

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ϗοτͳετϦʔϜ

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val channel = Channel(Channel.CONFLATED) userObserver.addOnChangeListener { user -> launch { channel.send(user) } } channel.consumeEach { user -> doSomething(user) }

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Flow

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ίʔϧυͳετϦʔϜ

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Preview status

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1.3.0-M1ͰExperimentalʹ

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val userFlow = flow { emit(observeUser()) } val seriesFlow = flow { emit(observeSeries()) } userFlow.combineLatest(seriesFlow) { user, series -> createItemModels(user, series) }.collect { itemModels -> // show items }

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Enjoy Kotlin Corou.nes life!