Kotlin x Architecture Components

#Events

どこでもKotlin #5 〜Android特集〜
https://m3-engineer.connpass.com/event/74261/

#Links

Kotlin + Architecture Component + Dagger2によるAndroidアプリ設計
https://goo.gl/sQijNq

Architecture Components + Flux (+ Kotlin)によるAndroidアプリ設計
https://goo.gl/tsUwbi

Twitter: 直接@Injectつけてうまくいく方法について
https://goo.gl/9tZQkm

Kotlinの型を知る ~後編~ プラットフォーム型とCollections
https://goo.gl/ApknrK

Transcript

1. Kotlin × Architecture
   Components ࣮ફ
   2018.01.18 Ͳ͜Ͱ΋Kotlin #5
   @satorufujiwara
   

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2. About me
   Satoru Fujiwara (@satorufujiwara)
   Android Engineer @CyberAgent ,Inc
   Organizer of Shibuya.apk
   ༁ॻ : Kotlin ΠϯɾΞΫγϣϯ
   ஶॻ : Android ΞϓϦઃܭύλʔϯೖ໳
   

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3. Kotlin & Me
   FRESH! ΛKotlinͰ։ൃ (2015೥3݄ʙ)
   Kotlin Advent Calendar
   - 2016೥ɺKotlinͰAndroid։ൃ͢Δํ΁ (2015೥, goo.gl/k97pqw )
   - JavaͰॻ͍ͯͨAndroidΤϯδχΞ͕ॳΊͯKotlinͰॻ͍ͯΈͨ (2016೥, goo.gl/huvTvT )
   - KotlinͷܕΛ஌Δ ~ޙฤ~ ϓϥοτϑΥʔϜܕͱCollections (2017೥, goo.gl/ApknrK )
   Kotlinೖ໳·Ͱͷॿ૸ಡຊ ( goo.gl/5vUT7o )
   Kotlin ΠϯɾΞΫγϣϯ (຋༁ 2017೥10݄31೔ग़൛)
   

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4. @satofurujiwara
   Kotlin × Architecture
   Components ࣮ફ
   4
   

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5. Architecture Componentsͱ͸
   • AndroidͷΞʔΩςΫνϟͷͨΊͷϥΠϒϥϦ܈
   • Google I/0 2017ͰॳΊͯЋ൛͕ެ։͞ΕΔ
   • 2017೥11݄6೔ʹ҆ఆ൛ͱͳΔ 1.0.0͕ެ։͞Ε͍ͯΔ
   • ʮݎ࿚Ͱɺςετ͕͠΍͘͢ɺอक͠΍͍͢ΞϓϦʯΛ࡞Δ
   

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6. Architecture ComponentsͷϞδϡʔϧ
   • LifeCycles - Activity΍FragmentͷϥΠϑαΠΫϧΛѻ͏ɺίΞͱͳΔϥΠϒϥϦ
   • ViewModel - UIʹؔ࿈ͨ͠σʔλΛอ࣋ɺ؅ཧ͢ΔͨΊͷΫϥε
   • LiveData - ObserverύλʔϯΛ࣋ͭσʔλอ࣋༻ͷΫϥε
   • Room - SQLiteͷϥούʔ
   • Paging - σʔλΛෳ਺ճʹ෼͚ͯಡΈࠐΉ
   ্هͷ͏ͪඞཁͳ΋ͷΛ૊Έ߹Θͤͯ࢖͏
   

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7. // ಋೖํ๏
   // build.gradle
   repositories {
   jcenter()
   google() // Google Maven RepositoryΛ௥Ճ
   }
   dependencies {
   // Lifecycles ͷΈ (ViewModel ΍ LiveData ͕ෆཁͷ৔߹)
   implementation "android.arch.lifecycle:runtime:1.0.3"
   kapt “android.arch.lifecycle:compiler:1.0.0" //Kotlinͷ৔߹͸kaptΛ༻͍Δ
   // ViewModelͱLiveData
   implementation "android.arch.lifecycle:extensions:1.0.0"
   kapt "android.arch.lifecycle:compiler:1.0.0"
   // Room
   implementation "android.arch.persistence.room:runtime:1.0.0"
   kapt "android.arch.persistence.room:compiler:1.0.0"
   // Paging
   implementation “android.arch.paging:runtime:1.0.0-alpha4-1" //·ͩAlpha൛
   }
   

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8. ࠓ೔ͷ࿩ͷείʔϓ
   • (LifeCycles)
   • ViewModel
   • LiveData
   ओʹViewModelͱLiveDataΛKotlinͰ࢖͏৔߹ͷ࿩Λ͠·͢
   

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9. ViewModelͱ͸
   • UI ʹؔ࿈ͨ͠σʔλΛอ࣋ɺ؅ཧ͢ΔͨΊͷΫϥε
   • ը໘ճసͷΑ͏ͳActivity͕࠶ੜ੒͞ΕΔ৔߹ʹ͓͍ͯ΋ɺΠϯ
   ελϯε͕ੜ͖࢒ΓɺσʔλΛอ࣋͠ଓ͚Δ
   • ্هΛ࣮ݱ͢ΔͨΊʹ಺෦తʹ͸setRetainInstance(true)ͳ
   HolderFragment಺ʹͦͷΠϯελϯε͕อ࣋͞Ε͍ͯΔ
   

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10. ViewModelͷऔಘ
    • ඞͣ ViewModelProvider::get Λ༻͍ͯऔಘ͢Δ
    • ViewModelProvider ͸ ViewModelProviders::of Ͱऔಘ͢Δ
    val viewModelProvider: ViewModelProvider = ViewModelProviders.of(this)
    //ViewModelΛܧঝͨ͠ΫϥεΛࢦఆ͢Δ
    val viewModel: MainViewModel = viewModelProvider.get(MainViewModel::class.java)
    

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11. ViewModelͷऔಘ
    • ViewModelProviders::of ͷҾ਺͸ FragmentActivity or Fragment
    • ࢦఆͨ͠Ϋϥε͕ҧ͑͹ ViewModel ͷΠϯελϯε΋ҟͳΔ
    • ಉ͡ FragmentActivity Λࢦఆ͢Ε͹ ViewModel ͸ಉ͡Πϯελϯε
    // in MainFragment
    viewModelA = ViewModelProviders.of(activity!!).get(MainViewModel::class.java)
    // viewModelAͱ͸ผͷΠϯελϯε
    viewModelB = ViewModelProviders.of(this).get(MainViewModel::class.java)
    

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12. ViewModelProvider.Factory
    • ViewModelΠϯελϯεੜ੒Λߦ͏ͨΊͷViewModelProvider.Factory Λࢦ
    ఆ͢Δ͜ͱ΋Ͱ͖Δ
    • ࢦఆ͠ͳ͚Ε͹σϑΥϧτͷ Factory ͕࢖ΘΕΔ
    //java
    public static ViewModelProvider of(@NonNull FragmentActivity activity, @NonNull Factory factory) {
    checkApplication(activity);
    return new ViewModelProvider(ViewModelStores.of(activity), factory);
    }
    public static ViewModelProvider of(@NonNull FragmentActivity activity) {
    initializeFactoryIfNeeded(checkApplication(activity));
    return new ViewModelProvider(ViewModelStores.of(activity), sDefaultFactory);
    }
    

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13. DefaultFactory
    • Class::newInstance Λݺͼग़ͯ͠ΠϯελϯεΛੜ੒͢Δ
    • AndroidViewModelΛܧঝ͍ͯ͠Δ৔߹͸
    • ίϯετϥΫλʹҾ਺Λ༩͍͑ͨ৔߹͸ಠࣗͷ Factory Λ࢖͏ඞ
    ཁ͕͋Δ
    modelClass.getConstructor(Application.class).newInstance(mApplication)
    

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14. //Android Architecture Blueprints todo-mvvm-live
    public class ViewModelFactory extends ViewModelProvider.NewInstanceFactory {
    private static volatile ViewModelFactory INSTANCE;
    private final Application mApplication;
    private final TasksRepository mTasksRepository;
    public static ViewModelFactory getInstance(Application application) {
    if (INSTANCE == null) {
    synchronized (ViewModelFactory.class) {
    if (INSTANCE == null) {
    INSTANCE = new ViewModelFactory(application, Injection.provideTasksRepository(application.getApplicationContext()));
    }
    }
    }
    return INSTANCE;
    }
    private ViewModelFactory(Application application, TasksRepository repository) {
    mApplication = application;
    mTasksRepository = repository;
    }
    @Override
    public T create(Class modelClass) {
    if (modelClass.isAssignableFrom(StatisticsViewModel.class)) {
    return (T) new StatisticsViewModel(mApplication, mTasksRepository);
    } else if (modelClass.isAssignableFrom(TaskDetailViewModel.class)) {
    return (T) new TaskDetailViewModel(mApplication, mTasksRepository);
    } else if (modelClass.isAssignableFrom(AddEditTaskViewModel.class)) {
    return (T) new AddEditTaskViewModel(mApplication, mTasksRepository);
    } else if (modelClass.isAssignableFrom(TasksViewModel.class)) {
    return (T) new TasksViewModel(mApplication, mTasksRepository);
    }
    throw new IllegalArgumentException("Unknown ViewModel class: " + modelClass.getName());
    }
    }
    

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15. ViewModelProvider.Factory
    • ಠࣗͰΠϯελϯε؅ཧ͢Δͷ͸େม
    • Dagger2(+Android֦ு)Λ࢖͍·͠ΐ͏
    • Architecture Components × Dagger2 × Kotlin ͸ϋϚΓϙΠϯτ
    ͕͍͔ͭ͘…
    • (Α͏΍͘Kotlinͷ࿩)
    

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16. // ಋೖํ๏
    // build.gradle
    ext.dagger_version = "2.14.1"
    dependencies {
    implementation "com.google.dagger:dagger:$dagger_version"
    implementation "com.google.dagger:dagger-android:$dagger_version"
    implementation "com.google.dagger:dagger-android-support:$dagger_version" // for support libs
    kapt "com.google.dagger:dagger-compiler:$dagger_version"
    kapt "com.google.dagger:dagger-android-processor:$dagger_version"
    }
    

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17. Dagger2 Λ༻͍ͨViewModelProvider.Factory
    • Dagger2 ͷ MultiBinding ػೳΛ࢖͏
    • ಉ͡ΫϥεͰ͋ͬͯ΋ Key Λࢦఆ͢Δ͜ͱͰɺͦΕʹରԠͨ͠
    ΠϯελϯεΛऔಘͰ͖Δ
    @Module
    internal abstract class MainModule {
    @Binds
    @IntoMap
    @ViewModelKey(MainViewModel::class) //Key໊ʹରԠ͢ΔΠϯελϯε͸Ҿ਺
    abstract fun bindMainViewModel(viewModel: MainViewModel): ViewModel
    }
    

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18. @Module
    internal abstract class MainModule {
    @Binds
    @IntoMap
    @ViewModelKey(MainViewModel::class) //Key໊
    abstract fun bindMainViewModel(viewModel: MainViewModel): ViewModel //Ҿ਺͕ରԠ͢Δ஋
    }
    //gererated Java code in DaggerAppComponents.java
    private Map, Provider>
    getMapOfClassOfAndProviderOfViewModel() {
    return ImmutableMap., Provider>of(
    MainViewModel.class, //Key໊
    (Provider) mainViewModelProvider //ରԠ͢Δ஋
    );
    }
    

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19. Dagger2 Λ༻͍ͨViewModelProvider.Factory
    • Dagger2 ʹΑͬͯੜ੒͞ΕΔ Map,
    Provider> ͔Β ViewModel ΛऔΓग़͢ FactoryΛ࡞
    Ε͹ྑ͍
    

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20. class ViewModelFactory @Inject constructor(
    private val creators: Map,
    @JvmSuppressWildcards Provider> // @JvmSuppressWildcards͕ඞਢ
    ) : ViewModelProvider.Factory {
    @Suppress("UNCHECKED_CAST")
    override fun create(modelClass: Class): T {
    var creator: Provider? = creators[modelClass]
    if (creator == null) {
    for ((key, value) in creators) {
    if (modelClass.isAssignableFrom(key)) {
    creator = value
    break
    }
    }
    }
    if (creator == null) throw IllegalArgumentException("unknown model class " + modelClass)
    try {
    return creator.get() as T
    } catch (e: Exception) {
    throw RuntimeException(e)
    }
    }
    }
    

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21. //Kotlin
    class ViewModelFactory
    @Inject constructor(private val creators:
    Map, Provider>)
    

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22. //Kotlin
    class ViewModelFactory
    @Inject constructor(private val creators:
    Map, Provider>)
    //Java expected
    Map, Provider>
    

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23. //Kotlin
    class ViewModelFactory
    @Inject constructor(private val creators:
    Map, Provider>)
    //Java expected
    Map, Provider>
    //Java actual : wildcard(?)͕ͭ͘
    Map,? extends Provider>
    //Java in java.inject package
    public interface Provider
    

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24. //Kotlin
    class ViewModelFactory
    @Inject constructor(private val creators:
    Map, @JvmSuppressWildcards Provider>)
    

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25. //Kotlin
    class ViewModelFactory
    @Inject constructor(private val creators:
    Map, @JvmSuppressWildcards Provider>)
    //Java expected
    Map, Provider>
    //Java actual : ظ଴Ͳ͓Γ
    Map, Provider>
    

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26. Architecture Components × Dagger2 × Kotlin
    • ಠࣗͷ ViewModelProvider.Factory ΛInject͢Δ
    • ViewModelProvider Λܦ༝ͤͣʹ ViewModelΛ௚઀ Inject ͢Δͷ͸ؒ
    ҧ͍
    @Inject lateinit var viewModelFactory: ViewModelProvider.Factory
    val viewModel: MainViewModel by lazy {
    ViewModelProviders.of(this, viewModelFactory).get(MainViewModel::class.java)
    }
    @Inject lateinit var viewModel : MainViewModel // ؒҧ͍
    

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27. ࢀߟ : ௚઀@Inject͚ͭͯ͏·͍͘͘ํ๏΋͋Δ ( goo.gl/9tZQkm )
    

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28. @satofurujiwara
    LiveData ͱ Kotlin
    28
    

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29. LiveDataͱ͸
    • ObserverύλʔϯΛ࣋ͭσʔλอ࣋༻ͷΫϥε
    • ؔ਺ observe Λ࢖ͬͯ஋Λ؂ࢹ͢Δ
    • ୈҰҾ਺ʹ LifecycleOwner (Activity/Fragment)Λࢦఆ͢Δ͜ͱͰɺϥΠϑαΠΫ
    ϧʹΑΔ؂ࢹͷఀࢭ͕Ͱ͖Δ
    viewModel.repos.observe(this, Observer {
    //reposͷ಺༰͕มߋ͞ΕͨΒݺͼग़͞ΕΔϥϜμ
    Log.d("MainActivity", "Repository List = $it")
    })
    

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30. LiveData::observe
    • ֦ுؔ਺Λఆٛ͢Δ͜ͱͰͪΐͬͱ͍͍ײ͡ʹͳΔ
    fun LiveData.observeBy(owner: LifecycleOwner, observer: (T?) -> Unit) = observe(owner,
    Observer {
    observer.invoke(it)
    })
    //after
    viewModel.repos.observeBy(this) {
    Log.d("MainActivity", "Repository List = $it")
    }
    //before
    viewModel.repos.observe(this, Observer {
    Log.d("MainActivity", "Repository List = $it")
    })
    

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31. LiveData::observe
    • ࣮͸ઌ΄Ͳͷ֦ுؔ਺ͷؔ਺ܕͷҾ਺ observer ͷҾ਺͸ T Ͱ͸
    ͳ͘ T? (ৗʹNullable)
    fun LiveData.observeBy(owner: LifecycleOwner, observer: (T?) -> Unit) = observe(owner, Observer {
    observer.invoke(it)
    })
    fun LiveData.observeBy(owner: LifecycleOwner, observer: (T) -> Unit) = observe(owner, Observer {
    observer.invoke(it) // Error!
    })
    viewModel.repos.observeBy(this) {
    val l = it.length //Error!
    }
    

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32. Observer
    • Observer ΠϯλϑΣʔεͷϝιουͷҾ਺ʹ @Nullable ͕͍ͭ
    ͍ͯΔ͔Β
    //java
    public interface Observer {
    void onChanged(@Nullable T t);
    }
    

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33. Observer಺Ͱͷnull-check
    • ֦ுؔ਺಺Ͱnull-checkΛ͢Ε͹͍͍ײ͡ʹ
    fun LiveData.observeNonNullBy(owner: LifecycleOwner, observer: (T) -> Unit) =
    observe(owner, Observer {
    it ?: return@Observer
    observer.invoke(it)
    })
    viewModel.repos.observeBy(this) {
    val l = it.length //OK!
    }
    

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34. ࢀߟݩ
    

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35. Observerͷ@Nullable
    • কདྷͷΞοϓσʔτͰফ͑Δ͔΋ʁ
    • ͦͷ৔߹͸Non-null͔Nullable͔Λ֤ࣗͰ൑அ͢Δ͜ͱʹͳΔ
    

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36. RxJava2ͷConsumerΠϯλϑΣʔε
    • Observer ͱಉ༷ͷ Single Abstract Method ΠϯλϑΣʔε
    • ͨͩ͠ @Nullable ͸͍͍ͭͯͳ͍
    //Java
    public interface Consumer {
    void accept(T t) throws Exception;
    }
    

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37. ܕύϥϝʔλʹNonNull/NullableΛࢦఆͨ͠ͱ͖ͷڍಈ
    

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38. JavaͰఆٛ͞ΕͨܕύϥϝʔλͱNullableܕ
    • NullableܕΛࢦఆ͢Ε͹NullableܕɺNon-nullܕΛࢦఆ͢Ε͹ϓ
    ϥοτϑΥʔϜܕ
    • ʮܕύϥϝʔλ͸ɺnull ڐ༰ܕͷܕͷఆٛʹ͸࠷ޙʹٙ໰ූ͕ඞ
    ཁͰ͋Γɺٙ໰ූ͕ͳ͍ܕ͸ null ඇڐ༰ܕͰ͋Δͱ͍͏ϧʔϧ
    ʹରͯ͠ͷ།Ұͷྫ֎ʯ(Kotlin ΠϯɾΞΫγϣϯ 6.1.10)
    

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39. ܕύϥϝʔλΛNonNullʹ͍ͨ͠৔߹͸
    • ܕύϥϝʔλʹ্ݶڥքͱͯ͠AnyܕΛࢦఆ͢Δ ( T:Any )
    

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40. ܕύϥϝʔλΛNonNullʹ͍ͨ͠৔߹͸
    • ܕύϥϝʔλʹ্ݶڥքͱͯ͠AnyܕΛࢦఆ͢Δ ( T:Any )
    • Kotlin ΠϯɾΞΫγϣϯ 9.1.4
    

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41. ͓·͚ : RxJava2 to LiveData
    • LiveData ͷ RxJava ༻֦ுΛಋೖ͢ΔࡍʹҎԼͷΑ͏ʹ֦ுؔ਺
    Λఆٛ͢Ε͹ɺϝιουνΣΠϯ͕ܨ͕Γ͍͍ײ͡ʹͳΔ
    fun Publisher.toLiveData() = LiveDataReactiveStreams.fromPublisher(this)
    val repos: LiveData> = dispatcher.onRefreshRepo
    .map { it.data }
    .observeOn(AndroidSchedulers.mainThread()) //͜͜·Ͱ͸Flowable
    .toLiveData()
    

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42. Architecture Components × Kotlin
    • Dagger2ͱ஥ྑ͘ͳΖ͏
    • ֦ுؔ਺Ͱ͍͍ײ͡ʹ
    • Qiitaʹ͸ࢀߟͷϦϙδτϦ΋͋ΔͷͰͥͻ
    • Kotlin + Architecture Component + Dagger2ʹΑΔAndroidΞϓϦઃܭ (goo.gl/sQijNq)
    • Architecture Components + Flux (+ Kotlin)ʹΑΔAndroidΞϓϦઃܭ (goo.gl/tsUwbi )
    

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43. Thank you!
    Have a Nice Kotlin!
    

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