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こんな時どう書くの? 逆引きKotlin入門
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Fukui Atsuko
May 30, 2018
Technology
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1.4k
こんな時どう書くの? 逆引きKotlin入門
2018/5/30 に開催される「Kotlin愛好会 vol1」向けの登壇資料です。
Kotlin初心者の方を対象に、逆引きのreferenceになるようなお話をします。
Fukui Atsuko
May 30, 2018
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Transcript
͜Μͳ࣌Ͳ͏ॻ͘ͷʁ ٯҾ͖Kotlinೖ 2018/5/30 KotlinѪձ vol1 Atsuko FUKUI
Agenda • ࣗݾհ • ຊͷΰʔϧ • ͜Μͳ࣌Ͳ͏ॻ͘ͷʁٯҾ͖Kotlinೖ • ·ͱΊ
ࣗݾհ • Ҫರࢠ / Fukui Atsuko • @muumuumuumuu • Android
Developer • Mercari, Inc.
ຊͷΰʔϧ • ؾܰʹKotlinΛॻ͖࢝ΊΒΕΔΑ͏ʹٯҾ͖ͷ ReferenceΛఏڙ͢Δ • Kotlinॳ৺ऀ͚Λఆ • Kotlin͢Ͱʹॻ͖ͳΕ͍ͯΔਓʮΘ͔Δʯ ʮKotlin͔Θ͍͍ʯͱࢥ͍ͳ͕Βฉ͍͍ͯͯԼ͞ ͍
• #love_kotlin ͷϋογϡλά͋Γ·͢Αʂ
͜Μͳ࣌Ͳ͏ॻ͘ͷʁ ٯҾ͖Kotlinೖ
มͷએݴ(1/3) • val / var म০ࢠͰม͕એݴͰ͖Δ • valfinal, var࠶ೖՄ
มͷએݴ(2/3) • ܕਪΛαϙʔτ • Φϓγϣφϧ • ܕͷએݴ࣌ʹ໌ࣔతʹ?Λ͚ͭͳ͍ͱnullΛ ڐ༰͠ͳ͍
มͷએݴ(3/3) • Ϋϥεʹଐ͢Δඞཁͳ͍(= ୈ1ڃΦϒδΣ Ϋτͱͯ͠એݴͰ͖Δ) • ఆʹconst
ؔͷએݴ(1/2) • funम০ࢠͰ͕ؔએݴͰ͖Δ • ҾͱΓͷࢦఆҎԼͷ௨Γ • த͕1ߦͰ͔͚Δ߹=Ͱܨ͛ͯreturnΛ লུͰ͖Δ
ؔͷએݴ(2/2) • σϑΥϧτҾͱ໊લ͖ҾΛαϙʔτ
݅ࣜ if (1/3) • Kotlinʹ͓͍ͯifࣜ(expression) • จ(statement)Ͱͳ͍ • ͭ·ΓΛฦ͢͜ͱ͕Ͱ͖Δ
݅ࣜ if (2/3) • ʢ೦ͳ͕Βʣࡾ߲ԋࢉࢠαϙʔτ͞Εͯ ͍ͳ͍ • ΤϧϏεԋࢉࢠ( ?: )αϙʔτ͞Ε͍ͯΔ
݅ࣜ if (3/3) • null νΣοΫείʔϓؔͱΦϓγϣφϧ ͷΈ߹Θ͕ͤΑ͘ΘΕΔ
݅ࣜ when (1/2) • if ಉ༷ʹwhenࣜ • whenͷޙΖͷ()ͷ͕ൺֱͷରʹͳΔ
݅ࣜ when (2/2) • whenͷޙΖͷ() ͳͯ͘OK • ൺֱରͷ͕ෳ͋Δ߹ʹศར
·ͱΊ
·ͱΊ • มͷએݴɺؔͷએݴɺ݅ࣜ • Kotlin͔Θ͍͍ʂʂ
͋Γ͕ͱ͏͍͟͝·ͨ͠