Java臭くないかわいい小鳥にする話 - メルカリ JP のコード例を交え -

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Javaष͘ͳ͍ ͔Θ͍͍খௗʹ͢Δ࿩ - ϝϧΧϦ JP ͷίʔυྫΛަ͑ - by @sintario Nov. 22, 2017 Mercari × Souzoh Android Talk @mercari

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͜͜·ͰΨν੎ͷ࿩Ͱ ർΕ·ͨ͠ΑͶʁ

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ͳͷͰٳܜલͷ  ͍ܰ࿩ʹ͠·͢Ͷ

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ࣗݾ঺հ • @sintario (Chronum Sintario) • ϝϧΧϦࣾྺ22೔Ίͷ৽ਓΤϯδχΞ • ീԦࢠࢢࡏॅʢژԦઢͱେߐށઢͰձ͑ΔΑʣ • ࠷ۙͷझຯ͸Ոఉͷෆཁ඼ΛϝϧΧϦͰചΓ͞͹͍ ͯച্ۚͰࣗ෼༻ͷ͓΋ͪΌΛങ͍ړΔ͜ͱʢ௚ۙ ͸੟ˑ͓ʹ͍͞Μͷ࣋ͬͯͳ͍רΛະ࢖༻৽඼300ԁ റΓͰूΊ͍ͯ·ͨ͠ʣ

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Career Background • JustSystems •Java, XML •ATOK Mac, Tweet ATOK, Objective-C, C++ • Lunascape •Web browser iOS app • DeNA •iOS apps, Android apps •Groovy, νϥγϧ, KenCoM, ͞ΜΆδελ •Healthcare, KenCoM, Ruby on Rails, Swift, Kotlin

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ӈͷਓᐌ͘ http://mercan.mercari.com/entry/2017/09/28/130000

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̏̕೔ؒͷ༗څফԽΛܦͯϝϧΧϦ΁ ͦͷؒͣͬͱՈࣄख఻͍ ϝϧΧϦ࢖͍ࠐΜͰ·ͨ͠

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Ͱɺٱ͠ͿΓʹ ίʔυॻ͍ͯΔΜ͕ͩ

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Զͦ͏͍͑͹ ϨϏϡʔ͓͡͞ΜͩͬͨΘ

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Kotlin Λ࢖ͬͯ ಡΊΔίʔυΛॻ͘࿩

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ͳΜͰࠓ͞Βͦͷ࿩Αʁ

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Android ͓͡͞Μͨͪʹ ݱ໾Ͱੜ͖࢒ͬͯཉ͍͠

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W○ntedly ͱ͔ݟΔͱ ͜͏͍͏ͷ͍ͬͺ͍ࡌͬͯΔ͚Ͳ ʮฐࣾ͸ฏۉ೥ྸ20୅Ͱ͢ʯ ʮຖि༵ۚ೔͸ŰƅŖžŖͯ͠·͢ʯ ͱ͔ͳΜͱ͔

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पΓʹ̏̌ޙ൒ա͗ͨ ΤϯδχΞԿਓ͍ΔΑʁ ελʔτΞοϓͷࣾ௕ͱ͔CTOͱ͔ʹͳΔͷ͔ͳʁ ͳΕΔͷ͔ͳʁ ໘઀Ͱ10೥ޙԿ͠·͔ͬͯ͢ݴΘΕͯ౴͑ΒΕΔʁ Ϛωʔδϝϯτ΄Μͱʹ΍Γ͍ͨʁ

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͓ͬ͞Μ͕ ΤϯδχΞͱͯ͠ੜ͖࢒Δʹ͸ Α͘ރΕ͍ͯΔ͜ͱ͕େࣄ

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Α͘ރΕ͍ͯΔͱ͸ • ແ೉ͳٕज़Ͱແ೉ʹ෺͕࡞ΕΔ • ଟগݹ͍஌ࣝΛ࢖͍·Θͯ͠एऀʹυϠΕΔ • ଟগ͸ษڧ΋·ͩͰ͖Δɺඈͼ͔ͭͳ͍͚Ͳ Ͱ͖Δ • ʢ࿝֐Β͘͠ͳ͍ײ͡Ͱ͋Δʣ

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μϝͳރΕํ • ΋͏ͳΜʹ΋ษڧͰ͖ͳ͍Ͱ͢ •֮͑ͨݴޠͻͱͭͰҰੜ৯͍ͬͯ͘ʢJavaͷ ਓͱ͔ʣ •֮͑ͨΠσΟΦϜҎ֎͸޻෉΋Ͱ͖ͳ͘ͳΔ •ૣ͍ͱ΄Μͱʹ20୅ͱ͔Ͱ΋ؕͬͯ͠·͏

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μϝͳރΕํ

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ͦΜͳ Ѫ͢΂͖͓ͬ͞Μͨͪʹ Kotlin Λ঑Ί͍ͨ

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Kotlin ͬͯ Կ͕͋Γ͕͍ͨͷʁ

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͓ͬ͞Μʹͱͬͯخ͍͜͠ͱ ͳΜͳͷʁ Kotlin ͬͯ Կ͕͋Γ͕͍ͨͷʁ

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ʢ৽ͨʹʣ ֮͑Δ͜ͱ͕গͳ͍

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ʢ৽ͨʹʣ ֮͑Δ͜ͱ͕গͳ͍ ݴޠ͕͍͍ҙຯͰශ૬ ͚ͩͲͪΌΜͱݱ୅ޠ +BWBͱ͔3VCZͱ͔4XJGUॻ͍ͯͨਓͳΒ ࢀೖোน௿͍

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ͿͬͪΌ͚ ͜Ε͚ͩ஌ͬͯΕ͹ ͍͍͓̺ͩͨ

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ͿͬͪΌ͚ ͜Ε͚ͩ஌ͬͯΕ͹ ͍͍͓̺ͩͨ ?., .let, .apply, when, ?: return, companion object, fun

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ͿͬͪΌ͚ ͜Ε͚ͩ஌ͬͯΕ͹ ͍͍͓̺ͩͨ ?., .let, .apply, when, ?: return, companion object, fun ͋ͱ͸ . ଧͬͯ Android Studio ઌੜʹڭ͑ͯ΋Β͍ͳ

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ίϯύΫτͳݴ༿Ͱ Readable ͳ ίʔυ͕ॻ͚Δ

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ݺΜͩʁಡΜͩʁ https://www.mercari.com/jp/search/? keyword=%E3%83%AA%E3%83%BC%E3%83%80%E3%83%96%E3%83%AB %E3%82%B3%E3%83%BC%E3%83%89 ষɹཧղ͠΍͍͢ίʔυ ষɹ໊લʹ৘ใΛ٧ΊࠐΉ ষɹޡղ͞Εͳ໊͍લ ষɹඒ͠͞ ষɹίϝϯτ͢΂͖͜ͱΛ஌Δ ষɹίϝϯτ͸ਖ਼֬Ͱ؆ܿʹ ষɹ੍ޚϑϩʔΛಡΈ΍͘͢͢Δ ষɹڊେͳࣜΛ෼ׂ͢Δ ষɹม਺ͱಡΈ΍͢͞ ষɹແؔ܎ͷԼҐ໰୊Λநग़͢Δ ষɹҰ౓ʹͭͷ͜ͱΛ ষɹίʔυʹࢥ͍ΛࠐΊΔ ষɹ୹͍ίʔυΛॻ͘ ষɹςετͱಡΈ΍͢͞ ষɹʮ෼ʗ࣌ؒΧ΢ϯλʯΛઃܭɾ࣮૷͢Δ

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obvious by deﬁnition Readable ͳΒ ίʔυ͕ಡΈ΍͍͢

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Readable ͳΒ ͍·͞Β ίʔσΟϯάͷఴ࡟͞Εͳ͍

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Readable ͳΒ ϏδωεϩδοΫʹ ूதͰ͖Δ

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Readable ͳΒ ϏδωεϩδοΫʹ ूதͰ͖Δ ॻ͋͘ͳͨ΋ɺಡΉ஥ؒ΋

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Readable ͳίʔυ͕ ॻ͚Δίʔμʔ͸ ࢌ͑ΒΕΔ

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ͭ·Γ

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Readable ͸ ͓͍͍͠

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͓͍͍͠ࢥ͍Λͤͯ͘͞ΕΔ Kotlin ͕͔Θ͍͘ͳΔ

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খௗ ,PUMJO

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͕͔ͩ͠͠

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͓ͬ͞Μ͸ ֶशݶք໨લͳͷͰ ಓ۩͚ͩ༩͑ΒΕΔͱ ܦݧͷԆ௕ઢ্Ͱ͔͠ ࢖͑ͳ͔ͬͨΓ͢Δͷͩʂ

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ྫ͑͹ ͜Μͳ Java ͕ ͋ͬͨͱ͢Δ͡Όͳ͍Ͱ͔͢ʔ

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public class ModalContentWebActivity extends SchemeWebActivity { public static Intent createIntent(Context context, String url){ return createIntent(context, url, null, null); } public static Intent createIntent(Context context, String url, String funcName, String params){ Intent intent = new Intent(context, ModalContentWebActivity.class); intent.putExtra(S.url, url); intent.putExtra(S.funcName, funcName); intent.putExtra(S.params, params); return intent; }

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Kotlinize it

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ͦͨ͠Β͞ʔ ૉͷ͓ͬ͞Μ͸ ͖ͬͱ͜Μͳͷॻ͘ΜͩΑͶʔ

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class ModalContentWebActivity: SchemeWebActivity() { companion object { fun createIntent(context: Context, url: String?): Intent { return createIntent(context, url, null, null) } fun createIntent(context: Context, url: String?, funcName: String?, params: String?): Intent { val intent = Intent(context, ModalContentWebActivity::class.java) intent.putExtra(S.url, url) intent.putExtra(S.funcName, funcName) intent.putExtra(S.params, params) return intent }

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͔Θ͍͘ͳ͍খௗ ୸Ր+BWBͷʹ͓͍͕͵͚ͳ͍

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·ͣ σϑΥϧτҾ਺ͬͯͷ͕ ͋ͬͯͳ

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class ModalContentWebActivity: SchemeWebActivity() { companion object { fun createIntent(context: Context, url: String?, funcName: String? = null, params: String? = null): Intent { val intent = Intent(context, ModalContentWebActivity::class.java) intent.putExtra(S.url, url) intent.putExtra(S.funcName, funcName) intent.putExtra(S.params, params) return intent }

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apply ͠·͠ΐ͏ͥ

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apply ͠·͠ΐ͏ͥ /** * Calls the speciﬁed function [block] with `this` value as its receiver * and returns `this` value. */ @kotlin.internal.InlineOnly public inline fun T.apply(block: T.() -> Unit): T { block(); return this }

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class ModalContentWebActivity: SchemeWebActivity() { companion object { fun createIntent(context: Context, url: String?, funcName: String? = null, params: String? = null): Intent { return Intent(context, ModalContentWebActivity::class.java).apply { putExtra(S.url, url) putExtra(S.funcName, funcName) putExtra(S.params, params) } }

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class ModalContentWebActivity: SchemeWebActivity() { companion object { fun createIntent(context: Context, url: String?, funcName: String? = null, params: String? = null): Intent { return Intent(context, ModalContentWebActivity::class.java).apply { putExtra(S.url, url) putExtra(S.funcName, funcName) putExtra(S.params, params) } } ͜ͷதͰ͸ this ͕ Intent ΠϯελϯεͳͷͰ Ϩγʔόʔهड़Λল͚Δ

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ॻ͖׳ΕΔͨΊͷίπͱͯ͠͸ ࠷ॳʹ return Hoge() ͬͯॻ͍ͪΌ͔ͬͯΒޙஔम ০͢Δߟ͑Ͱ΍Δͱ͍͍͔΋ ͋ͱ͸ val/var ͷΑ͏ͳҰ࣌ม਺ʹड͚औΔߟ͑Λ ࣺͯΔ͜ͱ

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୯Ұࣜؔ਺͸͞Βʹ

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class ModalContentWebActivity: SchemeWebActivity() { companion object { fun createIntent(context: Context, url: String?, funcName: String? = null, params: String? = null): Intent { return Intent(context, ModalContentWebActivity::class.java).apply { putExtra(S.url, url) putExtra(S.funcName, funcName) putExtra(S.params, params) } }

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class ModalContentWebActivity: SchemeWebActivity() { companion object { fun createIntent(context: Context, url: String?, funcName: String? = null, params: String? = null) = Intent(context, ModalContentWebActivity::class.java).apply { putExtra(S.url, url) putExtra(S.funcName, funcName) putExtra(S.params, params) }

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class ModalContentWebActivity: SchemeWebActivity() { companion object { fun createIntent(context: Context, url: String?, funcName: String? = null, params: String? = null) = Intent(context, ModalContentWebActivity::class.java).apply { putExtra(S.url, url) putExtra(S.funcName, funcName) putExtra(S.params, params) } ࣜͷ໭Γ஋Λฦ͢Αɺͱ͍͏௚ײతͳදݱʹɻ return ͱ͔΋͸΍ॻ͍ͨΒಐః

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࠷ॳͱൺֱ͠·͠ΐ͏

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class ModalContentWebActivity: SchemeWebActivity() { companion object { fun createIntent(context: Context, url: String?, funcName: String? = null, params: String? = null) = Intent(context, ModalContentWebActivity::class.java).apply { putExtra(S.url, url) putExtra(S.funcName, funcName) putExtra(S.params, params) }

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class ModalContentWebActivity: SchemeWebActivity() { companion object { fun createIntent(context: Context, url: String?, funcName: String? = null, params: String? = null) = Intent(context, ModalContentWebActivity::class.java).apply { putExtra(S.url, url) putExtra(S.funcName, funcName) putExtra(S.params, params) } ΋ͷ͛͑͢ߦ਺ݮΔͶ͑ จࣈ਺ݮΔͶ͑

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վΊͯಡΜͰΈΔͱϚδ͍͍ຊ https://www.mercari.com/jp/search/? keyword=%E3%83%AA%E3%83%BC%E3%83%80%E3%83%96%E3%83%AB %E3%82%B3%E3%83%BC%E3%83%89 ষɹཧղ͠΍͍͢ίʔυ ষɹ໊લʹ৘ใΛ٧ΊࠐΉ ষɹޡղ͞Εͳ໊͍લ ষɹඒ͠͞ ষɹίϝϯτ͢΂͖͜ͱΛ஌Δ ষɹίϝϯτ͸ਖ਼֬Ͱ؆ܿʹ ষɹ੍ޚϑϩʔΛಡΈ΍͘͢͢Δ ষɹڊେͳࣜΛ෼ׂ͢Δ ষɹม਺ͱಡΈ΍͢͞ ষɹແؔ܎ͷԼҐ໰୊Λநग़͢Δ ষɹҰ౓ʹͭͷ͜ͱΛ ষɹίʔυʹࢥ͍ΛࠐΊΔ ষɹ୹͍ίʔυΛॻ͘ ষɹςετͱಡΈ΍͢͞ ষɹʮ෼ʗ࣌ؒΧ΢ϯλʯΛઃܭɾ࣮૷͢Δ

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ͱ͍͏͜ͱͰ • খௗ͔Θ͍͍Αখௗ • ංେͨ͠ෛ࠴Λฦࡁ͢Δ͍ͭͰʹɺ͔Θ͍͍ίʔυʹɻ • ͔Θ͍͍খௗ͸ಡΈ΍͍͢Αɻ • Kotlin Β͘͠খ͔͚ͨ͘͞Β͓͡͞Μ·͍ͩΔΑͬͯݴ͑ ͦ͏ • ฐࣾͰ΋ Kotlin ԽΛ͢͢Ί͍ͯ·͢ͳ͏ʢPRϨϏϡʔͰ َͷΑ͏ʹఴ࡟͍ͯ͠·͢ʣ