Kotlinの言語機能をフル活用したAndroidアプリの開発

Hatena Engineer Seminar #9 で発表した内容です

1. KotlinͷݴޠػೳΛ ϑϧ׆༻ͨ͠ AndroidΞϓϦͷ։ൃ id:takuji31 Hatena Engineer Seminar #9
2. ஫ҙࣄ߲ • AndroidΞϓϦ։ൃͷલఏ஌ࣝͱͳΔΑ͏ͳ ෦෼ͷղઆ͸͠·ͤΜ • ͜ͷεϥΠυʹॻ͔Ε͍ͯΔKotlinͷίʔυ΍ ࢓༷͸όʔδϣϯ1.1.51࣌఺ͷ΋ͷͰ͢
3. ࣗݾ঺հ • ੢ྛ ୓ࢤ (ʹ͠͹΍͠ ͨ͘͡) • (hatena | twitter | github) takuji31 • גࣜձࣾ͸ͯͳ ΞϓϦέʔγϣϯΤϯδχΞ • ϒοΫϚʔΫΞϓϦνʔϜॴଐ
4. ࣗݾ঺հ • Android։ൃ 2010೥2݄ʙ • Kotlin 2014೥12݄ʙ • iOS΍Webͷ։ൃ΋ᅂΉ
5. ׆ಈ • Koreference • KotlinͰSharedPreferencesͷϞσϧΛ࡞Δ ϥΠϒϥϦʔ • github.com/takuji31/Koreference • Kansai.kt ӡӦ
6. ϓϥΠϕʔτ • Χϝϥ(not Ϩϯζ)পॅਓ • ϚΠϘ΢ϥʔ (AVG175) • ͏͗͞ • ΞΠίϯ͸͏ͪͷࢠͰ͢
7. ͱ͜ΖͰ
8. Έͳ͞ΜAndroidΞϓϦ ։ൃͯ͠·͔͢ʁ
9. Kotlinॻ͍ͯ·͔͢ʁ
10. Kotlinͷݴޠػೳ׆༻ ͍ͯ͠·͔͢ʁ
11. Null҆શ͚ͩͰຬ଍͍ͯ͠· ͤΜ͔ʁ
12. ࠓ೔͸͸ͯͳϒοΫϚʔΫ AndroidΞϓϦͰͷKotlin ׆༻ࣄྫΛ঺հ͠·͢
13. AGENDA • Kotlinಋೖ·ͰͷಓͷΓ • KotlinͷݴޠػೳΛ׆༻͢Δ • data class • Extension method / property • Delegated property
14. Kotlin ಋೖ·ͰͷಓͷΓ
15. ͸ͯͳͰͷ৽ٕज़ (ݴޠ΍ϛυϧ΢ΣΞ) ಋೖ
16. ಋೖ·Ͱ • ΤϯδχΞ͕ىҊ • ΤϯδχΞνʔϑձͰಋೖͷੋඇΛٞ࿦ • CTO͕ঝೝ
17. Kotlinͷ৔߹ • I/O Keynote͕ऴΘͬͨ௚ޙͷேɺKotlinಋೖ ىҊ (5/18) • ΤϯδχΞνʔϑձ • ঝೝ (5/19) • ͜͜·Ͱ͓Αͦ1೔൒
18. Kotlin+͸ͯͳϒοΫϚʔΫͷ৔߹ • (ि໌͚ͯ) 22೔͸νʔϜͷσΟϨΫλʔ͕
 ෆࡏͩͬͨͷͰ1ճٳΈ • 23೔ேʹσΟϨΫλʔͱձ࿩ͯ͠ಋೖܾఆ • ଈ೔ಋೖ
21. Kotlinͷ ݴޠػೳΛ ׆༻͢Δ
22. data class
23. ԿΒ͔ͷσʔλΛอ࣋͢Δͨ ΊͷΫϥε
24. Model΍DTOΛ࡞ΔͨΊͷ ศརػೳຬࡌ
25. ྫ) طଘͷmodelΛKotlinʹ ม׵͍ͨ͠
26. ม׵͸Convert Java file to Kotlin fileͰ
27. ୯७ͳม׵͚ͩͰΑ͍ͷ͔ʁ
28. ୯७ͳม׵͚ͩͰΑ͍ͷ͔ʁ • Nullableͳͷ͔NonNullͳͷ͔ࢦఆ͍ͨ͠ • equals/hashCode/toStringΛ࣮૷͍ͨ͠
29. ྫʣϢʔβʔͷmodelΛఆٛ • id • ໊લ • ੏ • ໊ • ϓϩϑΟʔϧ • ొ࿥ঢ়ଶ
30. 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; } }
31. ಡΊͳ͍
32. 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
33. equals/hashCode/toString →ࣗಈੜ੒
34. boilerplate codeΛ ࡟ݮ͖ͯͬ͢͠Γ
35. Extension
36. ֦ுؔ਺/֦ுϓϩύςΟʔ
37. طଘͷΫϥεʹ ؔ਺΍ϓϩύςΟʔΛੜ΍͢ (Α͏ʹݟͤΔ)࢓૊Έ
38. FragmentΛ֦ுϓϩύςΟʔͰ ֦ு͢Δ val Fragment.baseActivity: BaseActivity?
 get() = activity as BaseActivity?
 val Fragment.actionBar: ActionBar?
 get() = baseActivity?.supportActionBar ֦ு͍ͨ͠ܕ
    Λॻ͘ ͦͷଞ͸௨ৗͷ
    ϓϩύςΟʔͱಉ͡
39. 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
40. طଘͷJavaΫϥε΋ ֦ுͰ͖Δ
41. (Javaଆ͔Β͸) ୈ1Ҿ਺ΛϨγʔόʔʹͨ͠ staticϝιουʹݟ͑Δ
42. → طଘΫϥεͷҰ෦Λ KotlinԽͰ͖Δ
43. ػೳͷଟ͍ը໘Λ KotlinԽ
44. KotlinԽͷखॱ • ֦ுؔ਺Λఆٛ͢ΔϑΝΠϧΛ࡞Δ • JavaϑΝΠϧͷϝιουΛ֦ுؔ਺ʹͯ͠Kotlinଆʹఆ ٛ • Javaͷݩϝιου͔Β֦ுؔ਺Λݺͼग़͢ • ͋Δఔ౓ݩϑΝΠϧ͕૫ͤͨΒKotlinʹม׵ • ֦ுؔ਺ͷத਎Λݩϝιουʹ໭͍ͯ͘͠
45. pros • 1ͭͣͭdiff͕খ͘͞ͳΔͷͰϨϏϡʔ͠΍͢ ͍ • Ұ෦͚ͩKotlinԽ͢Δ͜ͱ͕Ͱ͖ͯؾܰʹ΍Ε Δ
46. cons • gitͷྺ࢙͕ফ໓ • ϑΝΠϧ͕෼͔ΕͯίʔυΛ௥͏ͷ͕গ͠େ มʹ
47. ֦ு͗͢͠Δͱ Θ͚͕Θ͔Βͳ͘ͳΔ
48. ͝ར༻͸ܭըతʹ
49. Delegated property
50. ҕৡϓϩύςΟʔ
51. propertyͷॲཧΛ ผͷΦϒδΣΫτʹ ҕৡͰ͖Δ
52. Data Binding Libraryͷ BaseObservableͷ มߋ௨஌ΛࣗಈԽ
53. 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
54. 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
55. 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
56. ศརͦ͏͚ͩͲ Ͳ͏͍͏༻్Ͱ࢖͑Δ͔ Θ͔Βͳ͍ʁ
57. SharedPreferencesͷૢ࡞
58. ͜ΕΛ࢖͍·͠ΐ͏ˠ https://github.com/ takuji31/Koreference
59. ͸ͯͳϒοΫϚʔΫͰ΋ ࢖͍ͬͯ·͢
60. σϑΥϧτͷ΋ͷ΋ ༻ҙ͞Ε͍ͯ·͢
61. σϑΥϧτͷ Delegated property(Ұ෦) • Delegates.notNull • not-null͕ͩॳظԽ࣌ʹॳظԽͰ͖ͳ͍ϓϩύςΟʔ • nullͷ··ΞΫηεͨ͠Βྫ֎ • lazy • ஗ԆॳظԽ • ࠷ॳͷΞΫηε࣌ʹҾ਺Ͱ౉ͨ͠ϒϩοΫͷ໭Γ஋Λฦͯ͠ Ωϟογϡ͢Δ
62. Kotlin͸ϞμϯͳݴޠͳͷͰ ॻ͘ίʔυ΋Ϟμϯʹ ͍͖ͯ͠·͠ΐ͏ :kotlin:
63. Enjoy Kotlin Life