Kotlin in Google IO 2017 FINAL CA.kt

# Event
https://cyberagent.connpass.com/event/57963/

# Links

- 2016年、KotlinでAndroid開発する方へ
- http://qiita.com/satorufujiwara/items/871c5b7b66c7691d82a8

- Google I/O 2017 : Introduction to Kotlin (和訳/要約)
- http://qiita.com/satorufujiwara/items/490c1499acec1a921258

- Life is Great and Everything Will Be Ok Kotlin is Here
- https://speakerdeck.com/jakewharton/life-is-great-and-everything-will-be-ok-kotlin-is-here-google-io-2017
- https://www.youtube.com/watch?v=fPzxfeDJDzY

- Using Kotlin Project in Android
- https://docs.google.com/document/d/1ReS3ep-hjxWA8kZi0YqDbEhCqTt29hG8P44aA9W0DM8/edit?hl=ja

- Tweet by @JakeWharton
- https://twitter.com/JakeWharton/status/685529621216018433

- Exploring Hidden Java Costs
- https://speakerdeck.com/jakewharton/exploring-hidden-java-costs-360-andev-july-2016

- Exploring Hidden Kotlin Costs
- https://medium.com/@BladeCoder/exploring-kotlins-hidden-costs-part-1-fbb9935d9b62

- Kotlin スコープ関数 用途まとめ@Qiita
- http://qiita.com/ngsw_taro/items/d29e3080d9fc8a38691e

- Kotlin + Architecture Component + Dagger2によるAndroidアプリ設計
- http://qiita.com/satorufujiwara/items/0f95ccfc3820d3ee1370

- Kotlin入門までの助走読本
- http://goo.gl/5vUT7o

Transcript

1. Kotlin in Google I/O 2017 Final Edition 2017.06.15 CA.kt #1 @satorufujiwara
2. About me Satoru Fujiwara (@satorufujiwara) Android Engineer @CyberAgent ,Inc Shibuya.apk
3. Kotlin & Me FRESH! ΛKotlinͰ։ൃ (2015೥3݄ʙ) Kotlin Advent Calendar (2015/2016) -ʮ2016೥ɺKotlinͰAndroid։ൃ͢Δํ΁ʯ @Qiita ( goo.gl/0medax ) Kotlinೖ໳·Ͱͷॿ૸ಡຊ ( goo.gl/5vUT7o )
4. Kotlin in Google I/O 2017
5. Google Keynote
6. Kotlin in Keynote • KotlinΛAndroidʹ͓͚Δެࣜݴޠͱͯ͠αϙʔτ • JetBrainsࣾΛύʔτʔφʔͱͯ͠Kotlinࡒஂͷઃཱ • طଘͷίʔυ(Java)ʹ΋͞ΒͳΔ౤ࢿΛ͢Δ
7. Why Kotlin? • Kotlin͸Androidͷ։ൃऀίϛϡχςΟ͕طʹٻΊ͍ͯͨݴޠͰɺ։ൃ ऀͷੜ࢈ੑΛߴΊΔ͜ͱ͕ग़དྷΔ • AndroidͷϥϯλΠϜͱͷ׬શͳޓ׵ੑ͕͋Γɺطଘͷίʔυͱͷ૬ޓ ӡ༻͕ՄೳͰ͋Δ • ૉ੖Β͍͠IDEʹΑΔαϙʔτ • ݴޠ͕੒ख़͠ɺ੡඼൛ͱͯ͠ϦϦʔεՄೳͳঢ়ଶͰ͋Δ
8. Developer Keynote
9. 4 big themes in Android • Kotlin • Android Studio & Libraries • App Quality & Success • Android Instant App
10. Kotlin in Developer Keynote • First-class Language ʹ • γϯλοΫεϊΠζͷগͳ͍ඒ͍͠ݴޠ • Android Studio 3.0 ʹ૊Έࠐ·ΕΔ • Java8 ͷ͞ΒͳΔαϙʔτ(Android O)
11. Android Studio 3.0
12. buid.gradle buildscript { ext.kotlin_version = '1.1.2-4' dependencies { classpath 'com.android.tools.build:gradle:3.0.0-alpha1' classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version" } } app/build.gradle apply plugin: ‘kotlin-android' dependencies { compile "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version" }
13. Why Kotlin? in Developer Keynote • Kotlin͸Javaͱͷ׬શͳ૬ޓӡ༻͕ग़དྷɺ1Ϋϥε͔ΒKotlinԽͰ͖Δ • 100% interoperable with Java and Android • ։ൃ͔Β5೥ܦͪɺݴޠ͕੒ख़͠ɺ੡඼൛ͱͯ͠ϦϦʔεՄೳͳঢ়ଶͰ͋Γɺ࣮ࡍʹ࢖ΘΕ͍ͯΔ • Flipboard,Pinterest ,Square Cash, Expedia • ݴޠ͕ૉ੖Β͍͠ͷʹՃ͑ɺIDEαϙʔτ͕ૉ੖Β͍͠ • Android Studioͷϕʔεͱͳ͍ͬͯΔIntelliJ IDEAͱಉ͡νʔϜ • Kotlin͸طʹApache2ϥΠηϯεͷΦʔϓϯιʔε͕ͩɺ͜Ε͔Β΋ΦʔϓϯιʔεϓϩδΣΫτ ͱͯ͠ඇӦརࡒஂ͕։ൃ͍ͯ͘͠
14. Sessions about Kotlin • Introduction to Kotlin • Life is Great and Everything Will Be Ok, Kotlin is Here
15. Introduction to Kotlin Google I/O 2017 : Introduction to Kotlin (࿨༁/ཁ໿) @Qiita goo.gl/U24xkw
16. Life is Great and Everything Will Be Ok, Kotlin is Here • KotlinͰAndroidΛ։ൃ͢Δ্ͰͷTips • by Jake Wharton (Square) @JakeWharton • KotlinΛ͍͔ʹͯ͠ಋೖ͔ͨ͠ʁ • by Christina Lee (Pinterest) @RunChristinaRun • https://speakerdeck.com/jakewharton/life-is-great-and-everything-will-be-ok- kotlin-is-here-google-io-2017 • https://www.youtube.com/watch?v=fPzxfeDJDzY
17. FRESH! ͰͷKotlin։ൃ • 2015೥3݄ Kotlinݕূ։࢝ɺ4݄͔Βຊ֨։ൃ (Kotlin M11) • 2016೥1݄21೔ αʔϏεϩϯν (Kotlin 1.0-beta3) • ʮ2016೥ɺKotlinͰAndroid։ൃ͢Δํ΁ʯ @Qiita ( goo.gl/0medax )
18. FRESH! ͰKotlinΛ࠾༻ͨ͠ཧ༝ • ݴޠ࢓༷ (Null Safety, Lambda, Collections) • JetBrains • 100% interoperable with Java
19. FRESH! ͰKotlinΛ࠾༻ͨ͠ཧ༝ • ݴޠ࢓༷ (Null Safety, Lambda, Collections) • JetBrains • 100% interoperable with Java -> ʮԿ͔͋ͬͨΒJavaʹ໭ΔΜͰʯΛޱบʹͯ͠։ൃ
20. FRESH! ͰKotlinΛ࠾༻ͨ͠ཧ༝ • ʰUsing Project Kotlin for Androidʱby Jake Wharton • goo.gl/1MyRCk
21. Using Project Kotlin in Android
22. Kotlin or Java • 2016೥2݄(Kotlin 1.0.0 Release)࣌఺Ͱͷબ୒ࢶ͸ • Java8 + Retrolambda • Kotlin • (Jack&Jill)
23. Chosen Kotlin goo.gl/Iopsz0
25. goo.gl/xxLvWE
26. Kotlin on Android. Now official
27. Kotlin͕ެࣜݴޠʹͳͬͯ • Android։ൃͰʮKotlinΛબͿ͜ͱʯ͕ग़དྷΔ • Ҿ͖ଓ͖Javaͷ஌ࣝ͸ඞཁ • Swiftͱ͸ࣅͯඇͳΔݴޠɺڞ௨Խ͸ग़དྷͳ͍ • Kotlin͸ࣗ༝౓͕ߴ͘ɺ͜Ε·ͰҎ্ʹֶशɾνʔϜͰͷٞ࿦͕ ඞཁ
28. Kotlin͸ࣗ༝౓͕ߴ͍
29. ྫ1: lambda
30. fun findEmails(users: List<User>, predicate: (String) -> (Boolean)) : List<User> { //… } findEmails(users, { value -> value.endsWith(".com") })
31. fun findEmails(users: List<User>, predicate: (String) -> (Boolean)) : List<User> { //… } findEmails(users, { value -> value.endsWith(".com") }) findEmails(users, { it.endsWith(".com") })
32. fun findEmails(users: List<User>, predicate: (String) -> (Boolean)) : List<User> { //… } findEmails(users, { value -> value.endsWith(".com") }) findEmails(users, { it.endsWith(".com") }) findEmails(users) { it.endsWith(".com") }
33. ྫ2: nullable
34. data class Money(val amount: Int, val currency: String) fun sumUp(money : Money?) { // money is nullable }
35. data class Money(val amount: Int, val currency: String) fun sumUp(money : Money?) { sumOfAmount += money!!.amount }
36. data class Money(val amount: Int, val currency: String) fun sumUp(money : Money?) { sumOfAmount += money!!.amount }
37. data class Money(val amount: Int, val currency: String) fun sumUp(money : Money?) { if (money != null) { sumOfAmount += money.amount } }
38. data class Money(val amount: Int, val currency: String) fun sumUp(money : Money?) { if (money != null) { sumOfAmount += money.amount } } fun sumUp(money : Money?) { money ?: return sumOfAmount += money.amount }
39. data class Money(val amount: Int, val currency: String) fun sumUp(money : Money?) { if (money != null) { sumOfAmount += money.amount } } fun sumUp(money : Money?) { money ?: return sumOfAmount += money.amount } fun sumUp(money : Money?) { sumOfAmount += money?.amount ?: 0 }
40. data class Money(val amount: Int, val currency: String) fun sumUp(money : Money?) { if (money != null) { sumOfAmount += money.amount } } fun sumUp(money : Money?) { money ?: return sumOfAmount += money.amount } fun sumUp(money : Money?) { sumOfAmount += money?.amount ?: 0 } fun sumUp(money : Money?) { money?.run { sumOfAmount += amount } }
41. ྫ3: είʔϓؔ਺
42. companion object { private const val KEY_USER = “user” fun newInstance(user: User): UserFragment { val fragment = UserFragment() val args = Bundle() args.putParcelable(KEY_USER, user) fragment.argument = args return fragment } }
43. companion object { private const val KEY_USER = “user” fun newInstance(user: User): UserFragment { val fragment = UserFragment() val args = Bundle() args.putParcelable(KEY_USER, user) fragment.argument = args return fragment } fun newInstance(user: User): UserFragment { val fragment = UserFragment() fragment.argument = Bundle().apply { putParcelable(KEY_USER, user) } return fragment } }
44. companion object { private const val KEY_USER = “user” fun newInstance(user: User): UserFragment { val fragment = UserFragment() val args = Bundle() args.putParcelable(KEY_USER, user) fragment.argument = args return fragment } fun newInstance(user: User): UserFragment { val fragment = UserFragment() fragment.argument = Bundle().apply { putParcelable(KEY_USER, user) } return fragment } fun newInstance(user: User) = UserFragment().apply { arguments = Bundle().apply { putParcelable(KEY_USER, user) } } }
45. είʔϓؔ਺ • let / with / run /apply / also • Kotlin είʔϓؔ਺ ༻్·ͱΊ@Qiita • http://qiita.com/ngsw_taro/items/d29e3080d9fc8a38691e • inline prefix public inline fun <T, R> T.run(block: T.() -> R): R = block()
46. Kotlin͸ࣗ༝౓͕ߴ͍
47. ٞ࿦͠ͳ͕ΒKotlinΛॻ͘ͷ͕ۙಓ
48. νʔϜͰͷKotlinֶशͷྫ • 4ਓͷAndroidνʔϜͰKotlinܦݧऀ͸ࢲ͚ͩ • PRͰϨϏϡʔ • ि1ͰKotlinษڧձ • Kotlin Koans࢖ͬͯɺͳͥͦͷ౴͑ʹͳΔͷ͔ͷղઆ • ผղ΍࣮ࡍͷϓϩμΫτͷࣄྫΛࣔ͠ͳ͕Β͞Βʹৄ͘͠ղઆ
49. ͓·͚
50. ͓·͚ • Google I/O 2017 ͱ͍͑͹ɺʰArchitecture Componentʱ • github.com/googlesamples/android-architecture-components • ্هʹαϯϓϧ͕ެ։͞Ε͍ͯΔ • GithubBrowserSample - An advanced sample that uses the Architecture components, Dagger and the Github API. Requires Android Studio 3.0 canary 1
51. ͓·͚ • ʰKotlin + Architecture Component + Dagger2ʹΑΔAndroidΞϓϦઃܭʱ@Qiita • goo.gl/z1p8zP • Ұ൪ϋϚͬͨͷ͸Dagger2ͷMultibindingػೳΛ࢖͏͜ͱ
52. //Kotlin class ViewModelFactory @Inject constructor(private val creators: Map<Class<out ViewModel>, Provider<ViewModel>>)
53. //Kotlin class ViewModelFactory @Inject constructor(private val creators: Map<Class<out ViewModel>, Provider<ViewModel>>) //Java expected Map<Class<? extends ViewModel>, Provider<ViewModel>>
54. //Kotlin class ViewModelFactory @Inject constructor(private val creators: Map<Class<out ViewModel>, Provider<ViewModel>>) //Java expected Map<Class<? extends ViewModel>, Provider<ViewModel>> //Java actual Map<Class<? extends ViewModel>,? extends Provider<ViewModel>> //Java in java.inject package public interface Provider<T>
55. //Kotlin class ViewModelFactory @Inject constructor(private val creators: Map<Class<out ViewModel>, @JvmSuppressWildcards Provider<ViewModel>>)
56. //Kotlin class ViewModelFactory @Inject constructor(private val creators: Map<Class<out ViewModel>, @JvmSuppressWildcards Provider<ViewModel>>) //Java expected Map<Class<? extends ViewModel>, Provider<ViewModel>> //Java actual Map<Class<? extends ViewModel>, Provider<ViewModel>>
57. For ‘100% interoperable with Java’ • @JvmSuppressWildcards • @JvmMultifileClass • @JvmField • @JvmStatic • @JvmOverloads
58. JavaͰͲ͏ͳ͍ͬͯΔͷ͔Λ૝૾͠ͳ͕Β KotlinΛॻ͘
59. How to start Kotlin • Official Site : kotl.in/ , kotl.in/android • Kotlin is awesome! (kotlin.link/) • Kotlin ελʔτϒοΫ(੺΂͜ຊ) • Kotlin Advent Calendar (2015/2016) • Kotlinೖ໳·Ͱͷॿ૸ಡຊ( goo.gl/5vUT7o )
60. Thank you ! Let’s enjoy Kotlin