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KotlinΛ࢖ͬͯࢥͬͨ10ͷίτ ࡾ௡ࢁ խن (chocomelon) 2017/0705 fukuoka.kt #1

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ࣗݾ঺հ ࡾ௡ࢁ խن (chocomelon) ωΠςΟϒΞϓϦΛओʹ୲౰ 2013೥ϐΫγϒೖࣾ Kotlinྺ 3िؒ

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ฐࣾͷKotlin࠾༻ঢ়گ

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pixivʢJavaʣ

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pixiv ίϛοΫʢJava & Kotlinʣ

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pixiv SketchʢJavaɺKotlinʹ͍ͨ͠ʣ

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PawooʢJavaɺKotlinʹ͍ͨ͠ʣ

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෱ԬͰ৽ن։ൃதͷΞϓϦ => Kotlin

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෱ԬͰ৽ن։ൃதͷΞϓϦ ɾKotlin ɾAndroid Architecture Components ɹɾViewModel, LiveData, Room ɾDataBinding ɾRxJava/Android

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KotlinΛ࢖ͬͯࢥ͏10ͷίτ

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1. Extension͕͢͹Β͍͠ fun ImageView.setImageUrl(imageUrl: String?) { if (imageUrl == null || !URLUtil.isValidUrl(imageUrl)) { return } Glide.with(context).load(imageUrl).into(this) }

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2. ؔ਺ܕ௒࠷ߴ͔Α arrayOf(1, 2, 3, 4, 5) // 1, 2, 3, 4, 5 .filter { it % 2 == 0 } // 2, 4 .map {it * 2 } // 4, 8 .sum() // 12

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3. σϑΥϧτ஋Ҿ/਺͕ศར fun hoge(fugaString: String, fooInt: Int = 0, barBoolean: = true) { // Do something } val fuga: Int = optionalVal1 ?: 5

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4. when͕εϚʔτ viewModel?.getDataSourceState()?.observe(this, Observer { when (it) { DataSourceState.SUCCESS -> infoView.setType(InfoView.Type.HIDE) DataSourceState.LOADING -> infoView.setType(InfoView.Type.LOADING) DataSourceState.EMPTY_DATA -> infoView.setType(InfoView.Type.NOTFOUND) DataSourceState.ERROR -> infoView.setType( InfoView.Type.ERROR, View.OnClickListener { reload() }) } })

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5. SmartCast͕ྑ͍ fun hoge(optionalVal1: String?, optionalVal2: String?) { if (optionalVal1 != null && optionalVal2 != null) { val hoge = optionalVal1 + optionalVal2 // Do something } } if (object is Person) { print(object.name) }

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6. είʔϓؔ਺͕ศར class HogeActivity: AppCompatActivity() { companion object { val BUNDLE_KEY_HOGE_INT = "HOGE_INT" fun createIntent(context: Context, hogeInt: Int): Intent = Intent(context, HogeActivity::class.java).apply { putExtra(BUNDLE_KEY_HOGE_INT, hogeInt) } } }

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7. let let ͕Ϝζ͍ optionalVal1?.let { optionalVal1 -> optionalVal2?.let { optionalVal2 -> // Do something } }

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7. let let ͕Ϝζ͍ if (optionalVal1 != null || optionalVal2 != null) { return } // Do something

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7. let let ͕Ϝζ͍ optionalVal1 ?: optionalVal2 ?: return // Do something

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7. let let ͕ຊ౰ʹϜζ͍ inline fun let(s: S?, t: T?, block: (s: S?, t: T?) -> R) { if (s != null && t != null) { block(s, t) } } let(optionalVal1, optionalVal2) { optionalVal1, optionalVal2 -> // Do something }

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8. Gson࢖͍ͬͯΔ৔߹͸஫ҙ✋ ɾNonNullͷobjectʹNull͕ೖͬͯ͘Δ ɾύʔε࣌͸Θ͔Β࣮ͣߦ࣌ʹࢮ͵ ɾmoshi࢖͓͏ https://github.com/square/moshi

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9. AndroidΤϯδχΞ͕΍Δؾ ɾؓࢄͱͯͨ͠Slack͕Kotlinͷॻ͖ํٞ࿦ ɹͰ੝Γ্͕Δ ɾࢼߦࡨޡָ͕͍͠ ɾ͙͢͸͡ΊΒΕΔ => Ұ෦Kotlinʹม͑ͯ΋ྑ͍͠ɺ ɹ ࣗಈม׵΋ͦͦ͜͜༗ೳ

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10. iOSͷΤϯδχΞ͕΍Δؾ ɾʮKotlinͩͬͨΒྑ͍Ͱ͢Αʯ ɾʮSwiftͱࣅͯΔ͡ΌΜʯ ɾʮָͦ͠͏ʢখฒʣʯ

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෱ԬΦϑΟεͰΤϯδχΞืूத ڵຯ͕͋Δํ͸·ͣϥϯνͰ΋͠·͠ΐ͏ʂ https://www.wantedly.com/projects/90433