Kotlinの言語機能をフル活用したAndroidアプリの開発

Transcript

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

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

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   ࣗݾ঺հ • ੢ྛ ୓ࢤ (ʹ͠͹΍͠ ͨ͘͡) • (hatena | twitter

   | github) takuji31 • גࣜձࣾ͸ͯͳ ΞϓϦέʔγϣϯΤϯδχΞ • ϒοΫϚʔΫΞϓϦνʔϜॴଐ
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   ࣗݾ঺հ • Android։ൃ 2010೥2݄ʙ • Kotlin 2014೥12݄ʙ • iOS΍Webͷ։ൃ΋ᅂΉ

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

   ӡӦ
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   ϓϥΠϕʔτ • Χϝϥ(not Ϩϯζ)পॅਓ • ϚΠϘ΢ϥʔ (AVG175) • ͏͗͞ •

   ΞΠίϯ͸͏ͪͷࢠͰ͢
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   ͱ͜ΖͰ

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   Έͳ͞ΜAndroidΞϓϦ ։ൃͯ͠·͔͢ʁ

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   Kotlinॻ͍ͯ·͔͢ʁ

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    Kotlinͷݴޠػೳ׆༻ ͍ͯ͠·͔͢ʁ

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    Null҆શ͚ͩͰຬ଍͍ͯ͠· ͤΜ͔ʁ

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

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    AGENDA • Kotlinಋೖ·ͰͷಓͷΓ • KotlinͷݴޠػೳΛ׆༻͢Δ • data class • Extension

    method / property • Delegated property
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    Kotlin ಋೖ·ͰͷಓͷΓ

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    ͸ͯͳͰͷ৽ٕज़ (ݴޠ΍ϛυϧ΢ΣΞ) ಋೖ

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    ಋೖ·Ͱ • ΤϯδχΞ͕ىҊ • ΤϯδχΞνʔϑձͰಋೖͷੋඇΛٞ࿦ • CTO͕ঝೝ

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    Kotlinͷ৔߹ • I/O Keynote͕ऴΘͬͨ௚ޙͷேɺKotlinಋೖ ىҊ (5/18) • ΤϯδχΞνʔϑձ • ঝೝ

    (5/19) • ͜͜·Ͱ͓Αͦ1೔൒
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    Kotlin+͸ͯͳϒοΫϚʔΫͷ৔߹ • (ि໌͚ͯ) 22೔͸νʔϜͷσΟϨΫλʔ͕
 ෆࡏͩͬͨͷͰ1ճٳΈ • 23೔ேʹσΟϨΫλʔͱձ࿩ͯ͠ಋೖܾఆ • ଈ೔ಋೖ

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    None
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    None
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    Kotlinͷ ݴޠػೳΛ ׆༻͢Δ

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    data class

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    ԿΒ͔ͷσʔλΛอ࣋͢Δͨ ΊͷΫϥε

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    Model΍DTOΛ࡞ΔͨΊͷ ศརػೳຬࡌ

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    ྫ) طଘͷmodelΛKotlinʹ ม׵͍ͨ͠

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    ม׵͸Convert Java file to Kotlin fileͰ

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    ୯७ͳม׵͚ͩͰΑ͍ͷ͔ʁ

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

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    ྫʣϢʔβʔͷmodelΛఆٛ • id • ໊લ • ੏ • ໊ •

    ϓϩϑΟʔϧ • ొ࿥ঢ়ଶ
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    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; } }
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    ಡΊͳ͍

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    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 CBDLJOH
    pFME ϓϩύςΟʔΛ
    DPOTUSVDUPSͰఆٛ
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    equals/hashCode/toString →ࣗಈੜ੒

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    boilerplate codeΛ ࡟ݮ͖ͯͬ͢͠Γ

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    Extension

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    ֦ுؔ਺/֦ுϓϩύςΟʔ

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    طଘͷΫϥεʹ ؔ਺΍ϓϩύςΟʔΛੜ΍͢ (Α͏ʹݟͤΔ)࢓૊Έ

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    FragmentΛ֦ுϓϩύςΟʔͰ ֦ு͢Δ val Fragment.baseActivity: BaseActivity?
 get() = activity as BaseActivity?


    val Fragment.actionBar: ActionBar?
 get() = baseActivity?.supportActionBar ֦ு͍ͨ͠ܕ
    Λॻ͘ ͦͷଞ͸௨ৗͷ
    ϓϩύςΟʔͱಉ͡
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    RealmͷProviderΛ֦ுؔ਺Ͱ ֦ு͢Δ fun Provider<Realm>.getAutoCloseObservable(): Observable<Realm> { 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
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    طଘͷJavaΫϥε΋ ֦ுͰ͖Δ

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    (Javaଆ͔Β͸) ୈ1Ҿ਺ΛϨγʔόʔʹͨ͠ staticϝιουʹݟ͑Δ

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    → طଘΫϥεͷҰ෦Λ KotlinԽͰ͖Δ

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    ػೳͷଟ͍ը໘Λ KotlinԽ

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    KotlinԽͷखॱ • ֦ுؔ਺Λఆٛ͢ΔϑΝΠϧΛ࡞Δ • JavaϑΝΠϧͷϝιουΛ֦ுؔ਺ʹͯ͠Kotlinଆʹఆ ٛ • Javaͷݩϝιου͔Β֦ுؔ਺Λݺͼग़͢ • ͋Δఔ౓ݩϑΝΠϧ͕૫ͤͨΒKotlinʹม׵

    • ֦ுؔ਺ͷத਎Λݩϝιουʹ໭͍ͯ͘͠
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    pros • 1ͭͣͭdiff͕খ͘͞ͳΔͷͰϨϏϡʔ͠΍͢ ͍ • Ұ෦͚ͩKotlinԽ͢Δ͜ͱ͕Ͱ͖ͯؾܰʹ΍Ε Δ

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    cons • gitͷྺ࢙͕ফ໓ • ϑΝΠϧ͕෼͔ΕͯίʔυΛ௥͏ͷ͕গ͠େ มʹ

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    ֦ு͗͢͠Δͱ Θ͚͕Θ͔Βͳ͘ͳΔ

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    ͝ར༻͸ܭըతʹ

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    Delegated property

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    ҕৡϓϩύςΟʔ

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    propertyͷॲཧΛ ผͷΦϒδΣΫτʹ ҕৡͰ͖Δ

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    Data Binding Libraryͷ BaseObservableͷ มߋ௨஌ΛࣗಈԽ

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    Delegated propertyͷఆٛ open class BaseObservableProperty<T : Any?>( vararg val propertyId:

    Int, var value: T ) : ReadWriteProperty<BaseObservable, T> { 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
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    Delegated propertyͷఆٛ class NonNullBaseObservableProperty<T : Any>(vararg propertyId: Int, value: T)

    : BaseObservableProperty<T>(propertyId = *propertyId, value = value) fun <T : Any?> BaseObservable.property(vararg propertyId: Int, value: T? = null) = BaseObservableProperty(propertyId = *propertyId, value = value) fun <T : Any> BaseObservable.nonNullProperty(vararg propertyId: Int, value: T) = NonNullBaseObservableProperty(propertyId = *propertyId, value = value) ܕ͕/PO/VMMͳ΋ͷ༻ͷఆٛ ֦ுؔ਺ʹ͓ͯ͘͠ͱ
    ࢖͏࣌ʹศར
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    ར༻͢Δ class ViewModel: BaseObservable() { @get:Bindable var users: List<User> by

    nonNullProperty(BR.users, value = emptyList()) fun requestUsers(): Disposable { return getUser .execute() .subscribeBy( onSuccess = { user -> this.users = users }, ) } } CZ
    ͷޙʹΦϒδΣΫτΛ౉͢ TFU͢Δ͜ͱͰࣗಈతʹ
    OPUJGZ1SPQFSUZ$IBOHFE͕
    ݺ͹ΕΔ
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    ศརͦ͏͚ͩͲ Ͳ͏͍͏༻్Ͱ࢖͑Δ͔ Θ͔Βͳ͍ʁ

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    SharedPreferencesͷૢ࡞

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

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    ͸ͯͳϒοΫϚʔΫͰ΋ ࢖͍ͬͯ·͢

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    σϑΥϧτͷ΋ͷ΋ ༻ҙ͞Ε͍ͯ·͢

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    σϑΥϧτͷ Delegated property(Ұ෦) • Delegates.notNull • not-null͕ͩॳظԽ࣌ʹॳظԽͰ͖ͳ͍ϓϩύςΟʔ • nullͷ··ΞΫηεͨ͠Βྫ֎ •

    lazy • ஗ԆॳظԽ • ࠷ॳͷΞΫηε࣌ʹҾ਺Ͱ౉ͨ͠ϒϩοΫͷ໭Γ஋Λฦͯ͠ Ωϟογϡ͢Δ
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    Kotlin͸ϞμϯͳݴޠͳͷͰ ॻ͘ίʔυ΋Ϟμϯʹ ͍͖ͯ͠·͠ΐ͏ :kotlin:

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    Enjoy Kotlin Life