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Kotlin in Google I/O 2017
Final Edition
2017.06.15 CA.kt #1
@satorufujiwara
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About me
Satoru Fujiwara (@satorufujiwara)
Android Engineer @CyberAgent ,Inc
Shibuya.apk
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Kotlin & Me
FRESH! ΛKotlinͰ։ൃ (20153݄ʙ)
Kotlin Advent Calendar (2015/2016)
-ʮ2016ɺKotlinͰAndroid։ൃ͢Δํʯ @Qiita ( goo.gl/0medax )
Kotlinೖ·Ͱͷॿಡຊ ( goo.gl/5vUT7o )
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Kotlin in Google I/O 2017
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Google Keynote
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Kotlin in Keynote
• KotlinΛAndroidʹ͓͚Δެࣜݴޠͱͯ͠αϙʔτ
• JetBrainsࣾΛύʔτʔφʔͱͯ͠Kotlinࡒஂͷઃཱ
• طଘͷίʔυ(Java)ʹ͞ΒͳΔࢿΛ͢Δ
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Why Kotlin?
• KotlinAndroidͷ։ൃऀίϛϡχςΟ͕طʹٻΊ͍ͯͨݴޠͰɺ։ൃ
ऀͷੜ࢈ੑΛߴΊΔ͜ͱ͕ग़དྷΔ
• AndroidͷϥϯλΠϜͱͷશͳޓੑ͕͋Γɺطଘͷίʔυͱͷ૬ޓ
ӡ༻͕ՄೳͰ͋Δ
• ૉΒ͍͠IDEʹΑΔαϙʔτ
• ݴޠ͕ख़͠ɺ൛ͱͯ͠ϦϦʔεՄೳͳঢ়ଶͰ͋Δ
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Developer Keynote
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4 big themes in Android
• Kotlin
• Android Studio & Libraries
• App Quality & Success
• Android Instant App
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Kotlin in Developer Keynote
• First-class Language ʹ
• γϯλοΫεϊΠζͷগͳ͍ඒ͍͠ݴޠ
• Android Studio 3.0 ʹΈࠐ·ΕΔ
• Java8 ͷ͞ΒͳΔαϙʔτ(Android O)
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Android Studio 3.0
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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"
}
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Why Kotlin? in Developer Keynote
• KotlinJavaͱͷશͳ૬ޓӡ༻͕ग़དྷɺ1Ϋϥε͔ΒKotlinԽͰ͖Δ
• 100% interoperable with Java and Android
• ։ൃ͔Β5ܦͪɺݴޠ͕ख़͠ɺ൛ͱͯ͠ϦϦʔεՄೳͳঢ়ଶͰ͋Γɺ࣮ࡍʹΘΕ͍ͯΔ
• Flipboard,Pinterest ,Square Cash, Expedia
• ݴޠ͕ૉΒ͍͠ͷʹՃ͑ɺIDEαϙʔτ͕ૉΒ͍͠
• Android Studioͷϕʔεͱͳ͍ͬͯΔIntelliJ IDEAͱಉ͡νʔϜ
• KotlinطʹApache2ϥΠηϯεͷΦʔϓϯιʔε͕ͩɺ͜Ε͔ΒΦʔϓϯιʔεϓϩδΣΫτ
ͱͯ͠ඇӦརࡒஂ͕։ൃ͍ͯ͘͠
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Sessions about Kotlin
• Introduction to Kotlin
• Life is Great and Everything Will Be Ok, Kotlin is Here
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Introduction to Kotlin
Google I/O 2017 : Introduction to Kotlin (༁/ཁ) @Qiita
goo.gl/U24xkw
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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
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FRESH! ͰͷKotlin։ൃ
• 20153݄ Kotlinݕূ։࢝ɺ4݄͔Βຊ֨։ൃ (Kotlin M11)
• 20161݄21 αʔϏεϩϯν (Kotlin 1.0-beta3)
• ʮ2016ɺKotlinͰAndroid։ൃ͢Δํʯ @Qiita ( goo.gl/0medax )
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FRESH! ͰKotlinΛ࠾༻ͨ͠ཧ༝
• ݴޠ༷ (Null Safety, Lambda, Collections)
• JetBrains
• 100% interoperable with Java
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FRESH! ͰKotlinΛ࠾༻ͨ͠ཧ༝
• ݴޠ༷ (Null Safety, Lambda, Collections)
• JetBrains
• 100% interoperable with Java
-> ʮԿ͔͋ͬͨΒJavaʹΔΜͰʯΛޱบʹͯ͠։ൃ
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FRESH! ͰKotlinΛ࠾༻ͨ͠ཧ༝
• ʰUsing Project Kotlin for Androidʱby Jake Wharton
• goo.gl/1MyRCk
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Using Project Kotlin in Android
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Kotlin or Java
• 20162݄(Kotlin 1.0.0 Release)࣌Ͱͷબࢶ
• Java8 + Retrolambda
• Kotlin
• (Jack&Jill)
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Chosen Kotlin
goo.gl/Iopsz0
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No content
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goo.gl/xxLvWE
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Kotlin on Android. Now official
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Kotlin͕ެࣜݴޠʹͳͬͯ
• Android։ൃͰʮKotlinΛબͿ͜ͱʯ͕ग़དྷΔ
• Ҿ͖ଓ͖Javaͷࣝඞཁ
• SwiftͱࣅͯඇͳΔݴޠɺڞ௨Խग़དྷͳ͍
• Kotlinࣗ༝͕ߴ͘ɺ͜Ε·ͰҎ্ʹֶशɾνʔϜͰͷ͕ٞ
ඞཁ
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Kotlinࣗ༝͕ߴ͍
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ྫ1: lambda
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fun findEmails(users: List, predicate: (String) -> (Boolean))
: List {
//…
}
findEmails(users, { value -> value.endsWith(".com") })
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fun findEmails(users: List, predicate: (String) -> (Boolean))
: List {
//…
}
findEmails(users, { value -> value.endsWith(".com") })
findEmails(users, { it.endsWith(".com") })
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fun findEmails(users: List, predicate: (String) -> (Boolean))
: List {
//…
}
findEmails(users, { value -> value.endsWith(".com") })
findEmails(users, { it.endsWith(".com") })
findEmails(users) {
it.endsWith(".com")
}
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ྫ2: nullable
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data class Money(val amount: Int, val currency: String)
fun sumUp(money : Money?) {
// money is nullable
}
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data class Money(val amount: Int, val currency: String)
fun sumUp(money : Money?) {
sumOfAmount += money!!.amount
}
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data class Money(val amount: Int, val currency: String)
fun sumUp(money : Money?) {
sumOfAmount += money!!.amount
}
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data class Money(val amount: Int, val currency: String)
fun sumUp(money : Money?) {
if (money != null) {
sumOfAmount += money.amount
}
}
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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
}
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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
}
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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
}
}
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ྫ3: είʔϓؔ
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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
}
}
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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
}
}
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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)
}
}
}
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είʔϓؔ
• let / with / run /apply / also
• Kotlin είʔϓؔ ༻్·ͱΊ@Qiita
• http://qiita.com/ngsw_taro/items/d29e3080d9fc8a38691e
• inline prefix
public inline fun T.run(block: T.() -> R): R = block()
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Kotlinࣗ༝͕ߴ͍
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ٞ͠ͳ͕ΒKotlinΛॻ͘ͷ͕ۙಓ
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νʔϜͰͷKotlinֶशͷྫ
• 4ਓͷAndroidνʔϜͰKotlinܦݧऀࢲ͚ͩ
• PRͰϨϏϡʔ
• ि1ͰKotlinษڧձ
• Kotlin Koansͬͯɺͳͥͦͷ͑ʹͳΔͷ͔ͷղઆ
• ผղ࣮ࡍͷϓϩμΫτͷࣄྫΛࣔ͠ͳ͕Β͞Βʹৄ͘͠ղઆ
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͓·͚
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͓·͚
• Google I/O 2017 ͱ͍͑ɺʰArchitecture 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
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͓·͚
• ʰKotlin + Architecture Component + Dagger2ʹΑΔAndroidΞϓϦઃܭʱ@Qiita
• goo.gl/z1p8zP
• Ұ൪ϋϚͬͨͷDagger2ͷMultibindingػೳΛ͏͜ͱ
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//Kotlin
class ViewModelFactory
@Inject constructor(private val creators:
Map, Provider>)
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//Kotlin
class ViewModelFactory
@Inject constructor(private val creators:
Map, Provider>)
//Java expected
Map, Provider>
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//Kotlin
class ViewModelFactory
@Inject constructor(private val creators:
Map, Provider>)
//Java expected
Map, Provider>
//Java actual
Map,? extends Provider>
//Java in java.inject package
public interface Provider
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//Kotlin
class ViewModelFactory
@Inject constructor(private val creators:
Map, @JvmSuppressWildcards Provider>)
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//Kotlin
class ViewModelFactory
@Inject constructor(private val creators:
Map, @JvmSuppressWildcards Provider>)
//Java expected
Map, Provider>
//Java actual
Map, Provider>
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For ‘100% interoperable with Java’
• @JvmSuppressWildcards
• @JvmMultifileClass
• @JvmField
• @JvmStatic
• @JvmOverloads
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JavaͰͲ͏ͳ͍ͬͯΔͷ͔Λ૾͠ͳ͕Β
KotlinΛॻ͘
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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·Ͱͷॿಡຊ( goo.gl/5vUT7o )
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Thank you !
Let’s enjoy Kotlin