KotlinͷݴޠػೳΛ ϑϧ׆༻ͨ͠ AndroidΞϓϦͷ։ൃ id:takuji31 Hatena Engineer Seminar #9

஫ҙࣄ߲ • AndroidΞϓϦ։ൃͷલఏ஌ࣝͱͳΔΑ͏ͳ ෦෼ͷղઆ͸͠·ͤΜ • ͜ͷεϥΠυʹॻ͔Ε͍ͯΔKotlinͷίʔυ΍ ࢓༷͸όʔδϣϯ1.1.51࣌఺ͷ΋ͷͰ͢

ࣗݾ঺հ • ੢ྛ ୓ࢤ (ʹ͠͹΍͠ ͨ͘͡) • (hatena | twitter | github) takuji31 • גࣜձࣾ͸ͯͳ ΞϓϦέʔγϣϯΤϯδχΞ • ϒοΫϚʔΫΞϓϦνʔϜॴଐ

ࣗݾ঺հ • Android։ൃ 2010೥2݄ʙ • Kotlin 2014೥12݄ʙ • iOS΍Webͷ։ൃ΋ᅂΉ

׆ಈ • Koreference • KotlinͰSharedPreferencesͷϞσϧΛ࡞Δ ϥΠϒϥϦʔ • github.com/takuji31/Koreference • Kansai.kt ӡӦ

ϓϥΠϕʔτ • Χϝϥ(not Ϩϯζ)পॅਓ • ϚΠϘ΢ϥʔ (AVG175) • ͏͗͞ • ΞΠίϯ͸͏ͪͷࢠͰ͢

ͱ͜ΖͰ

Έͳ͞ΜAndroidΞϓϦ ։ൃͯ͠·͔͢ʁ

Kotlinॻ͍ͯ·͔͢ʁ

Kotlinͷݴޠػೳ׆༻ ͍ͯ͠·͔͢ʁ

Null҆શ͚ͩͰຬ଍͍ͯ͠· ͤΜ͔ʁ

ࠓ೔͸͸ͯͳϒοΫϚʔΫ AndroidΞϓϦͰͷKotlin ׆༻ࣄྫΛ঺հ͠·͢

AGENDA • Kotlinಋೖ·ͰͷಓͷΓ • KotlinͷݴޠػೳΛ׆༻͢Δ • data class • Extension method / property • Delegated property

Kotlin ಋೖ·ͰͷಓͷΓ

͸ͯͳͰͷ৽ٕज़ (ݴޠ΍ϛυϧ΢ΣΞ) ಋೖ

ಋೖ·Ͱ • ΤϯδχΞ͕ىҊ • ΤϯδχΞνʔϑձͰಋೖͷੋඇΛٞ࿦ • CTO͕ঝೝ

Kotlinͷ৔߹ • I/O Keynote͕ऴΘͬͨ௚ޙͷேɺKotlinಋೖ ىҊ (5/18) • ΤϯδχΞνʔϑձ • ঝೝ (5/19) • ͜͜·Ͱ͓Αͦ1೔൒

Kotlin+͸ͯͳϒοΫϚʔΫͷ৔߹ • (ि໌͚ͯ) 22೔͸νʔϜͷσΟϨΫλʔ͕
 ෆࡏͩͬͨͷͰ1ճٳΈ • 23೔ேʹσΟϨΫλʔͱձ࿩ͯ͠ಋೖܾఆ • ଈ೔ಋೖ

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Kotlinͷ ݴޠػೳΛ ׆༻͢Δ

data class

ԿΒ͔ͷσʔλΛอ࣋͢Δͨ ΊͷΫϥε

Model΍DTOΛ࡞ΔͨΊͷ ศརػೳຬࡌ

ྫ) طଘͷmodelΛKotlinʹ ม׵͍ͨ͠

ม׵͸Convert Java file to Kotlin fileͰ

୯७ͳม׵͚ͩͰΑ͍ͷ͔ʁ

୯७ͳม׵͚ͩͰΑ͍ͷ͔ʁ • Nullableͳͷ͔NonNullͳͷ͔ࢦఆ͍ͨ͠ • equals/hashCode/toStringΛ࣮૷͍ͨ͠

ྫʣϢʔβʔͷmodelΛఆٛ • id • ໊લ • ੏ • ໊ • ϓϩϑΟʔϧ • ొ࿥ঢ়ଶ

Javaͷmodel(Ұ෦) public class JavaUser { private final long id; private String firstName; private String lastName; private String profile; private boolean registered; public JavaUser(long id, String firstName, String lastName, String profile, boolean registered) { this.id = id; this.firstName = firstName; this.lastName = lastName; this.profile = profile; this.registered = registered; } public long getId() { return id; } public String getFirstName() { return firstName; } public void setFirstName(String firstName) { this.firstName = firstName; } public String getLastName() { return lastName; } public void setLastName(String lastName) { this.lastName = lastName; } public String getProfile() { return profile; } public void setProfile(String profile) { this.profile = profile; } public boolean isRegistered() { return registered; } public void setRegistered(boolean registered) { this.registered = registered; } public String getFullName() { return firstName + " " + lastName; } }

ಡΊͳ͍

Kotlinͷmodel data class JavaUser( val id: Long, var firstName: String, var lastName: String, var profile: String?, var isRegistered: Boolean = false ) { val fullName: String get() = firstName + " " + lastName } ಄ʹEBUB Λ͚ͭΔ શͯͷ CBDLJOHpFME ϓϩύςΟʔΛ DPOTUSVDUPSͰఆٛ

equals/hashCode/toString →ࣗಈੜ੒

boilerplate codeΛ ࡟ݮ͖ͯͬ͢͠Γ

Extension

֦ுؔ਺/֦ுϓϩύςΟʔ

طଘͷΫϥεʹ ؔ਺΍ϓϩύςΟʔΛੜ΍͢ (Α͏ʹݟͤΔ)࢓૊Έ

FragmentΛ֦ுϓϩύςΟʔͰ ֦ு͢Δ val Fragment.baseActivity: BaseActivity?
 get() = activity as BaseActivity?
 val Fragment.actionBar: ActionBar?
 get() = baseActivity?.supportActionBar ֦ு͍ͨ͠ܕ Λॻ͘ ͦͷଞ͸௨ৗͷ ϓϩύςΟʔͱಉ͡

RealmͷProviderΛ֦ுؔ਺Ͱ ֦ு͢Δ fun Provider.getAutoCloseObservable(): Observable { val realm = get() realm.use { return Observable.create { emitter -> val instance = get() emitter.setCancellable { instance.close() } emitter.onNext(instance) } } } ֦ு͍ͨ͠ܕ Λॻ͘ ͦͷଞ͸௨ৗͷ ؔ਺ͱಉ͡ (FOFSJDTͷ ܕύϥϝʔλʔ΋ࢦఆՄ
 ϓϩύςΟʔ΋ಉ༷

طଘͷJavaΫϥε΋ ֦ுͰ͖Δ

(Javaଆ͔Β͸) ୈ1Ҿ਺ΛϨγʔόʔʹͨ͠ staticϝιουʹݟ͑Δ

→ طଘΫϥεͷҰ෦Λ KotlinԽͰ͖Δ

ػೳͷଟ͍ը໘Λ KotlinԽ

KotlinԽͷखॱ • ֦ுؔ਺Λఆٛ͢ΔϑΝΠϧΛ࡞Δ • JavaϑΝΠϧͷϝιουΛ֦ுؔ਺ʹͯ͠Kotlinଆʹఆ ٛ • Javaͷݩϝιου͔Β֦ுؔ਺Λݺͼग़͢ • ͋Δఔ౓ݩϑΝΠϧ͕૫ͤͨΒKotlinʹม׵ • ֦ுؔ਺ͷத਎Λݩϝιουʹ໭͍ͯ͘͠

pros • 1ͭͣͭdiff͕খ͘͞ͳΔͷͰϨϏϡʔ͠΍͢ ͍ • Ұ෦͚ͩKotlinԽ͢Δ͜ͱ͕Ͱ͖ͯؾܰʹ΍Ε Δ

cons • gitͷྺ࢙͕ফ໓ • ϑΝΠϧ͕෼͔ΕͯίʔυΛ௥͏ͷ͕গ͠େ มʹ

֦ு͗͢͠Δͱ Θ͚͕Θ͔Βͳ͘ͳΔ

͝ར༻͸ܭըతʹ

Delegated property

ҕৡϓϩύςΟʔ

propertyͷॲཧΛ ผͷΦϒδΣΫτʹ ҕৡͰ͖Δ

Data Binding Libraryͷ BaseObservableͷ มߋ௨஌ΛࣗಈԽ

Delegated propertyͷఆٛ open class BaseObservableProperty( vararg val propertyId: Int, var value: T ) : ReadWriteProperty { override fun getValue( thisRef: BaseObservable, property: KProperty<*>): T { return value } override fun setValue( thisRef: BaseObservable, property: KProperty<*>, value: T) { this.value = value propertyId.forEach(thisRef::notifyPropertyChanged) } } 3FBE8SJUF1SPQFSUZ ΠϯλʔϑΣΠεΛ࣮૷ HFU7BMVFTFU7BMVFΛ ఆٛ UIJTͷࢀরͱQSPQFSUZͷ ৘ใ͕౉͞ΕΔ

Delegated propertyͷఆٛ class NonNullBaseObservableProperty(vararg propertyId: Int, value: T) : BaseObservableProperty(propertyId = *propertyId, value = value) fun BaseObservable.property(vararg propertyId: Int, value: T? = null) = BaseObservableProperty(propertyId = *propertyId, value = value) fun BaseObservable.nonNullProperty(vararg propertyId: Int, value: T) = NonNullBaseObservableProperty(propertyId = *propertyId, value = value) ܕ͕/PO/VMMͳ΋ͷ༻ͷఆٛ ֦ுؔ਺ʹ͓ͯ͘͠ͱ ࢖͏࣌ʹศར

ར༻͢Δ class ViewModel: BaseObservable() { @get:Bindable var users: List by nonNullProperty(BR.users, value = emptyList()) fun requestUsers(): Disposable { return getUser .execute() .subscribeBy( onSuccess = { user -> this.users = users }, ) } } CZͷޙʹΦϒδΣΫτΛ౉͢ TFU͢Δ͜ͱͰࣗಈతʹ OPUJGZ1SPQFSUZ$IBOHFE͕ ݺ͹ΕΔ

ศརͦ͏͚ͩͲ Ͳ͏͍͏༻్Ͱ࢖͑Δ͔ Θ͔Βͳ͍ʁ

SharedPreferencesͷૢ࡞

͜ΕΛ࢖͍·͠ΐ͏ˠ https://github.com/ takuji31/Koreference

͸ͯͳϒοΫϚʔΫͰ΋ ࢖͍ͬͯ·͢

σϑΥϧτͷ΋ͷ΋ ༻ҙ͞Ε͍ͯ·͢

σϑΥϧτͷ Delegated property(Ұ෦) • Delegates.notNull • not-null͕ͩॳظԽ࣌ʹॳظԽͰ͖ͳ͍ϓϩύςΟʔ • nullͷ··ΞΫηεͨ͠Βྫ֎ • lazy • ஗ԆॳظԽ • ࠷ॳͷΞΫηε࣌ʹҾ਺Ͱ౉ͨ͠ϒϩοΫͷ໭Γ஋Λฦͯ͠ Ωϟογϡ͢Δ

Kotlin͸ϞμϯͳݴޠͳͷͰ ॻ͘ίʔυ΋Ϟμϯʹ ͍͖ͯ͠·͠ΐ͏ :kotlin:

Enjoy Kotlin Life