Android Architecture Components - Introduction

As the developers we constantly ask ourselves a question - what architecture should we follow? MVP, MVVM, MVC - those are only a few which we know. Fortunately, our problems come to an end! Recently Google published a set of libraries called Architecture Components. During the presentation, we’ll find out how to use a database library Room, how to get control over activity lifecycle and how to be up to date with LiveData.

Transcript

1. Architecture
2. @p_szklarska Architecture Components Introduction
3. @p_szklarska Architecture Components Introduction
4. Architecture Components Introduction
5. @p_szklarska Paulina Szklarska Android Developer @ DroidsOnRoids Toast Wrocław meetups co-org GDG Wrocław co-org Women Techmakers Wrocław lead cat owner travel enthusiast @p_szklarska @pszklarska @pszklarska
6. @p_szklarska 1. What are Architecture Components? 2. Room 3. Lifecycle-aware components 1. Lifecycle Components 2. ViewModel 3. Live Data 4. Application architecture example (*) Agenda
7. @p_szklarska What are Architecture Components?
9. @p_szklarska ARCHITECTURE COMPONENTS ROOM LIFECYCLE COMPONENTS VIEW MODEL LIVE DATA PAGING LIBRARY @p_szklarska
10. @p_szklarska ARCHITECTURE COMPONENTS ROOM LIFECYCLE COMPONENTS VIEW MODEL LIVE DATA PAGING LIBRARY @p_szklarska NAVIGATION COMPONENTS WORK MANAGER
11. @p_szklarska Room
12. @p_szklarska Room Entity Single database table DAO Defines methods to access database Database Holds entities and DAOs @p_szklarska Abstraction layer over SQLite
13. @p_szklarska Why another database library? •less boilerplate code (thanks to annotations) •SQL statement compile-time validation (less crashes) •full compatibility with LiveData and RxJava •easy to use •easy to test •easy to migrate @p_szklarska
14. @p_szklarska Entity @p_szklarska
15. @p_szklarska data class Cat( val id: Int, val name: String, val url: String )a Entity @p_szklarska
16. @p_szklarska @Entity data class Cat( val id: Int, val name: String, val url: String )a Entity
17. @p_szklarska @Entity data class Cat( @PrimaryKey val id: Int, val name: String, val url: String )a Entity
18. @p_szklarska DAO
19. @p_szklarska interface CatDao { }a DAO
20. @p_szklarska @Dao interface CatDao { }a DAO
21. @p_szklarska @Dao interface CatDao { @Insert fun insert(cat: Cat) @Update fun update(cat: Cat) @Delete fun delete(cat: Cat) }a DAO
22. @p_szklarska @Dao interface CatDao { @Query("SELECT * FROM kittens") fun getAllCats(): List<Cat> @Insert fun insert(cat: Cat) @Update fun update(cat: Cat) @Delete fun delete(cat: Cat) }a DAO
23. @p_szklarska @Dao interface CatDao { @Query("SELECT * FROM kittens") fun getAllCats(): List<Cat> }a DAO
24. @p_szklarska @Dao interface CatDao { @Query("SELECT * FROM kittens") fun getAllCats(): List<Cat> @Query("SELECT * FROM kittens WHERE id=:id") fun getCatById(id: Int): List<Cat> }a DAO
25. @p_szklarska Database
26. @p_szklarska class CatDatabase { }a Database
27. @p_szklarska @Database(entities = [(Cat::class)], version = 1) class CatDatabase { }a Database
28. @p_szklarska @Database(entities = [(Cat::class)], version = 1) abstract class CatDatabase : RoomDatabase() { }a Database
29. @p_szklarska @Database(entities = [(Cat::class)], version = 1) abstract class CatDatabase : RoomDatabase() { abstract fun catDao(): CatDao }a Database
30. @p_szklarska @Database(entities = [(Cat::class)], version = 1) abstract class CatDatabase : RoomDatabase() { abstract fun catDao(): CatDao private val DB_NAME = "catDatabase.db" fun create(context: Context): CatDatabase { return Room.databaseBuilder( context, CatDatabase::class.java, DB_NAME).build() } }a Database
31. @p_szklarska catDao.apply { insert(cat) val allCats = getAllCats() } Database
32. @p_szklarska Testing
33. @p_szklarska @RunWith(AndroidJUnit4::class) class CatEntityTest { private lateinit var catDao: CatDao private lateinit var catDatabase: CatDatabase @Before fun setUp() { val context = InstrumentationRegistry.getTargetContext() catDatabase = Room .inMemoryDatabaseBuilder( context, CatDatabase::class.java) .build() catDao = catDatabase.catDao() }a @After fun tearDown() { catDatabase.close() }a }a Testing
34. @p_szklarska @RunWith(AndroidJUnit4::class) class CatEntityTest { private lateinit var catDao: CatDao private lateinit var catDatabase: CatDatabase @Before fun setUp() { val context = InstrumentationRegistry.getTargetContext() catDatabase = Room .inMemoryDatabaseBuilder( context, CatDatabase::class.java) .build() catDao = catDatabase.catDao() }a @After fun tearDown() { catDatabase.close() }a }a Testing
35. @p_szklarska @RunWith(AndroidJUnit4::class) class CatEntityTest { ... @Test fun saveAndReadCat() { val fluffyToBeSaved = Cat(name = "Fluffy") catDao.insert(fluffyToBeSaved) val fluffyFromDatabase = catDao.getCatsByName("Fluffy") assertEquals(fluffyToBeSaved, fluffyFromDatabase) } ... } Testing
36. @p_szklarska Room - tl;dr • less boilerplate code • SQL statement compile-time validation • full compatibility with other Architecture Components and RxJava • easy to use • easy to test • easy to migrate
37. @p_szklarska Lifecycle-aware Components
38. Lifecycle-aware Components
39. @p_szklarska Lifecycle-aware Components LIFECYCLE COMPONENTS LIFECYCLE OWNER LIFECYCLE OBSERVER - FragmentActivity - Fragment (support) - AppCompatActivity
40. @p_szklarska Lifecycle-aware Components INITIALIZED RESUMED STARTED CREATED DESTROYED RESUMED STARTED CREATED ON_CREATE ON_START ON_RESUME ON_PAUSE ON_STOP ON_DESTROY
41. @p_szklarska LifecycleObserver
42. @p_szklarska class LocationActivity : AppCompatActivity(), LocationListener { lateinit var locationManager: LocationManager override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) locationManager = LocationManager() }a override fun onStart() { super.onStart() locationManager.addLocationListener() }a override fun onStop() { locationManager.removeLocationListener() super.onStop() }a override fun onLocationChanged(location: Location) { // only this is interesting }a }a LifecycleObserver
43. @p_szklarska class LocationActivity : AppCompatActivity(), LocationListener { lateinit var locationManager: LocationManager override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) locationManager = LocationManager() }a override fun onStart() { super.onStart() locationManager.addLocationListener() }a override fun onStop() { locationManager.removeLocationListener() super.onStop() }a override fun onLocationChanged(location: Location) { // only this is interesting }a }a LifecycleObserver
44. @p_szklarska class LocationManager {a fun addLocationListener() {a // register location listener }a fun removeLocationListener() {a // unregister location listener }a }a LifecycleObserver
45. @p_szklarska class LocationManager() : LifecycleObserver {a fun addLocationListener() {a // register location listener }a fun removeLocationListener() {a // unregister location listener }a }a LifecycleObserver
46. @p_szklarska class LocationManager(lifecycleOwner: LifecycleOwner) : LifecycleObserver {a init {a lifecycleOwner.lifecycle.addObserver(this) }b fun addLocationListener() {a // register location listener }a fun removeLocationListener() {a // unregister location listener }a }a LifecycleObserver
47. @p_szklarska class LocationManager(lifecycleOwner: LifecycleOwner) : LifecycleObserver {a init {a lifecycleOwner.lifecycle.addObserver(this) }b @OnLifecycleEvent(Lifecycle.Event.ON_START) fun addLocationListener() {a // register location listener }a @OnLifecycleEvent(Lifecycle.Event.ON_STOP) fun removeLocationListener() {a // unregister location listener }a }a LifecycleObserver
48. @p_szklarska class LocationActivity : AppCompatActivity(), LocationListener { lateinit var locationManager: LocationManager override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) locationManager = LocationManager()this }a override fun onStart() { super.onStart() locationManager.addLocationListener() }b override fun onStop() { locationManager.removeLocationListener() super.onStop() }b override fun onLocationChanged(location: Location) { // only this is interesting }a }a LifecycleObserver
49. @p_szklarska class LocationActivity : AppCompatActivity(), LocationListener { lateinit var locationManager: LocationManager override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) locationManager = LocationManager(this) }a override fun onLocationChanged(location: Location) { // only this is interesting }a }a LifecycleObserver
50. @p_szklarska Lifecycle Observer It’s the LocationManager which cares about the Lifecycle. So it should be able to do it without the activity babysitting itself. I’m sure if you look at your code today, your onStart(), onStop() methods are like, at least 20, 30 lines of code. We want them to be zero lines of code. ~Yigit Boyar, Software Enginner, Google, Google I/O ‚17
51. @p_szklarska ViewModel
52. @p_szklarska ViewModel Data Source ? ACTIVITY ACTIVITY RECREATED Rotation Data Source
53. @p_szklarska ViewModel ACTIVITY ACTIVITY RECREATED ViewModel • don’t worry about UI data source • data will wait for us • data will be always updated even after activity recreating Rotation
54. @p_szklarska ViewModel
55. @p_szklarska class MainViewModel : ViewModel() { }a ViewModel
56. @p_szklarska class MainViewModel : ViewModel() { val kittiesNames: List<String> = gimmeKitties() }a ViewModel
57. @p_szklarska class MainViewModel(application: Application) : AndroidViewModel(application) { val kittiesNames: List<String> = gimmeKitties() }a ViewModel
58. @p_szklarska class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) }a }a ViewModel
59. @p_szklarska class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) val viewModel = ViewModelProviders .of(this) .get(MainViewModel::class.java) }a }a ViewModel
60. @p_szklarska class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) val viewModel = ViewModelProviders .of(this) .get(MainViewModel::class.java) showKitties(viewModel.kittiesNames) }a }a ViewModel
61. @p_szklarska LiveData
62. @p_szklarska LiveData
63. @p_szklarska Lifecycle + Data
64. @p_szklarska LiveData LiveData<List<String>> observes notifies only if activity is at least started List<String>
65. @p_szklarska LiveData
66. @p_szklarska class MainViewModel : ViewModel() { val kittiesNames: List<String> = gimmeKitties() } LiveData
67. @p_szklarska class MainViewModel : ViewModel() { private val kittiesNamesLiveData = MutableLiveData<List<String>>() }a LiveData
68. @p_szklarska class MainViewModel : ViewModel() { private val kittiesNamesLiveData = MutableLiveData<List<String>>() val kittiesNames = kittiesNamesLiveData as LiveData<List<String>> }a LiveData
69. @p_szklarska class MainViewModel : ViewModel() { private val kittiesNamesLiveData = MutableLiveData<List<String>>() init { repository.fetchNewKitties { kittiesNamesLiveData.postValue(it) }a } val kittiesNames = kittiesNamesLiveData as LiveData<List<String>> }a LiveData
70. @p_szklarska class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) val viewModel = ViewModelProviders .of(this) .get(MainViewModel::class.java) showKitties(viewModel.kittiesNames) }a }a LiveData
71. @p_szklarska class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) val viewModel = ViewModelProviders .of(this) .get(MainViewModel::class.java) }a }a LiveData
72. @p_szklarska class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) val viewModel = ViewModelProviders .of(this) .get(MainViewModel::class.java) viewModel.kittiesNames.observe(this, Observer { kitties -> showKitties(kitties) }) }a }a LiveData
73. @p_szklarska LiveData - Transformation
74. @p_szklarska private val userList = MutableLiveData<List<User>>() LiveData - Transformation
75. @p_szklarska private val userList = MutableLiveData<List<User>>() private val usernamesList: LiveData<List<String>> = Transformations.map(userList, { users -> users.map { it.name } }) LiveData - Transformation
76. @p_szklarska LiveData + DataBinding
77. @p_szklarska <?xml version="1.0" encoding="utf-8"?> <layout xmlns:android="http://schemas.android.com/apk/res/android"> <data> <variable name="viewModel" type="pl.pszklarska.databinding.HomeViewModel" /> </data> <LinearLayout android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical"> <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:text=“@{viewModel.kittyName}" /> <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:text=“@{Integer.toString(viewModel.kittyAge)}" /> </LinearLayout> </layout> LiveData + DataBinding
78. @p_szklarska <?xml version="1.0" encoding="utf-8"?> <layout xmlns:android="http://schemas.android.com/apk/res/android"> <data> <variable name="viewModel" type="pl.pszklarska.databinding.HomeViewModel" /> </data> <LinearLayout android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical"> <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:text=“@{viewModel.kittyName}" /> <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:text=“@{Integer.toString(viewModel.kittyAge)}" /> </LinearLayout> </layout> LiveData + DataBinding
79. @p_szklarska <?xml version="1.0" encoding="utf-8"?> <layout xmlns:android="http://schemas.android.com/apk/res/android"> <data> <variable name="viewModel" type="pl.pszklarska.databinding.HomeViewModel" /> </data> <LinearLayout android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical"> <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:text=“@{viewModel.kittyName}" /> <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:text=“@{Integer.toString(viewModel.kittyAge)}" /> </LinearLayout> </layout> LiveData + DataBinding
80. @p_szklarska class HomeViewModel : ViewModel() { private val kittyRepository = KittyRepository() val kittyName = ObservableField<String>() val kittyAge = ObservableInt() init { kittyRepository.receiveNewKitties { kittyName.set(it.name) kittyAge.set(it.age) }a }a }a LiveData + DataBinding
81. @p_szklarska class HomeViewModel : ViewModel() { private val kittyRepository = KittyRepository() val kittyName = MutableLiveData<String>() val kittyAge = MutableLiveData<Int>() init { kittyRepository.receiveNewKitties { kittyName.postValue(it.name) kittyAge.postValue(it.age) }a }a }a LiveData + DataBinding
82. @p_szklarska class HomeActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) val binding: ActivityMainBinding = DataBindingUtil.setContentView( this, R.layout.activity_main) val viewModel = ViewModelProviders.of(this) .get(HomeViewModel::class.java) binding.viewModel = viewModel binding.setLifecycleOwner(this) }a }a LiveData + DataBinding
83. @p_szklarska LiveData + Room
84. @p_szklarska @Dao interface CatDao { @Query("SELECT * FROM kittens") fun getAllCats(): LiveData<List<Cat>> }a LiveData + Room
85. @p_szklarska LiveData - tl;dr •keeps your UI always updated (follows observer pattern) •no memory leaks (data bound with lifecycle) •no data sent to stopped activity
86. @p_szklarska Architecture example
87. @p_szklarska Architecture example •MVVM (Model-View-ViewModel) •ViewModel stores data for View ACTIVITY FRAGMENT VIEWMODEL LiveData REPOSITORY View ViewModel Model
88. @p_szklarska Architecture example •MVVM (Model-View-ViewModel) •ViewModel stores data for View REPOSITORY Model
89. @p_szklarska Architecture example •MVVM (Model-View-ViewModel) •ViewModel stores data for View REPOSITORY Model LOCAL Room REMOTE Retrofit
90. @p_szklarska class MainViewModel( private val repository: KittyRepository ) : ViewModel() { private val kittiesNames = MutableLiveData<List<String>>() init { repository.fetchNewKitties { kittiesNamesLiveData.postValue(it) }a }a val kittiesNamesLiveData = kittiesNames as LiveData<List<String>> }a Architecture Example
91. @p_szklarska class MainViewModelFactory : ViewModelProvider.NewInstanceFactory() { private val repository = KittyRepository() override fun <T : ViewModel> create(modelClass: Class<T>): T { return MainViewModel(repository) as T } } Architecture Example
92. @p_szklarska class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) }a }a Architecture Example
93. @p_szklarska class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) val viewModel = ViewModelProviders.of(this, MainViewModelFactory()) .get(MainViewModel::class.java) }a }a Architecture Example
94. @p_szklarska class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) val viewModel = ViewModelProviders.of(this, MainViewModelFactory()) .get(MainViewModel::class.java) viewModel.kitties.observe(this, Observer { kitties -> // show kitties list }) }a }a Architecture Example
95. @p_szklarska class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) val viewModel = ViewModelProviders.of(this, MainViewModelFactory()) .get(MainViewModel::class.java) viewModel.kitties.observe(this, Observer { kitties -> // show kitties list }) kittyDetailsList.setOnItemClickListener { kittyName -> viewModel.requestKittyDetails(kittyName) } }a }a Architecture Example
96. @p_szklarska class MainViewModel( private val repository: KittyRepository ) : ViewModel() { private val kittiesNamesLiveData = MutableLiveData<List<String>>() init { repository.fetchNewKitties { kittiesNamesLiveData.postValue(it) }a }a val kitties = kittiesNamesLiveData as LiveData<List<String>> }a Architecture Example
97. @p_szklarska class MainViewModel( private val repository: KittyRepository ) : ViewModel() { private val kittiesNamesLiveData = MutableLiveData<List<String>>() private val kittyDetailsLiveData = MutableLiveData<Kitty>() init { repository.fetchNewKitties { kittiesNamesLiveData.postValue(it) }a }a val kitties = kittiesNamesLiveData as LiveData<List<String>> val kittyDetails = kittyDetailsLiveData as LiveData<Kitty> }a Architecture Example
98. @p_szklarska class MainViewModel( private val repository: KittyRepository ) : ViewModel() { private val kittiesNamesLiveData = MutableLiveData<List<String>>() private val kittyDetailsLiveData = MutableLiveData<Kitty>() init { repository.fetchNewKitties { kittiesNamesLiveData.postValue(it) }a }a fun requestKittyDetails(name: String) { val kittyDetails = repository.fetchKittyDetails(name) kittyDetailsLiveData.postValue(kittyDetails) }a val kitties = kittiesNamesLiveData as LiveData<List<String>> val kittyDetails = kittyDetailsLiveData as LiveData<Kitty> }a Architecture Example
99. @p_szklarska class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) val viewModel = ViewModelProviders.of(this, MainViewModelFactory()) .get(MainViewModel::class.java) viewModel.kitties.observe(this, Observer { kitties -> // show kitties list }) kittyDetailsList.setOnItemClickListener { kittyName -> viewModel.requestKittyDetails(kittyName) }a }a }a Architecture Example
100. @p_szklarska class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) val viewModel = ViewModelProviders.of(this, MainViewModelFactory()) .get(MainViewModel::class.java) viewModel.kitties.observe(this, Observer { kitties -> // show kitties list }) kittyDetailsList.setOnItemClickListener { kittyName -> viewModel.requestKittyDetails(kittyName) }a viewModel.kittyDetails.observe(this, Observer { kitty -> // show kitty details }) }a }a Architecture Example
101. @p_szklarska class MainViewModelTest { @Test fun `observer is notified when kitty details are requested`() { }a }a Architecture Example
102. @p_szklarska @RunWith(MockitoJUnitRunner::class) class MainViewModelTest { @Mock private lateinit var repository: KittyRepository @InjectMocks private lateinit var viewModel: MainViewModel @Test fun `observer is notified when kitty details are requested`() { }a }a Architecture Example
103. @p_szklarska @RunWith(MockitoJUnitRunner::class) class MainViewModelTest { @Rule @JvmField val rule = InstantTaskExecutorRule() @Mock private lateinit var repository: KittyRepository @InjectMocks private lateinit var viewModel: MainViewModel @Test fun `observer is notified when kitty details are requested`() { }a }a Architecture Example
104. @p_szklarska @RunWith(MockitoJUnitRunner::class) class MainViewModelTest { @Rule @JvmField val rule = InstantTaskExecutorRule() @Mock private lateinit var observer: Observer<Kitty> @Mock private lateinit var repository: KittyRepository @InjectMocks private lateinit var viewModel: MainViewModel @Test fun `observer is notified when kitty details are requested`() { viewModel.kittyDetails.observeForever(observer) }a }a Architecture Example
105. @p_szklarska @RunWith(MockitoJUnitRunner::class) class MainViewModelTest { @Rule @JvmField val rule = InstantTaskExecutorRule() @Mock private lateinit var observer: Observer<Kitty> @Mock private lateinit var repository: KittyRepository @InjectMocks private lateinit var viewModel: MainViewModel private val kitty = Kitty("Fluffy", 5) @Test fun `observer is notified when kitty details are requested`() { viewModel.kittyDetails.observeForever(observer) whenever(repository.fetchKittyDetails(any())).thenReturn(kitty) }a }a Architecture Example
106. @p_szklarska @RunWith(MockitoJUnitRunner::class) class MainViewModelTest { @Rule @JvmField val rule = InstantTaskExecutorRule() @Mock private lateinit var observer: Observer<Kitty> @Mock private lateinit var repository: KittyRepository @InjectMocks private lateinit var viewModel: MainViewModel private val kitty = Kitty("Fluffy", 5) @Test fun `observer is notified when kitty details are requested`() { viewModel.kittyDetails.observeForever(observer) whenever(repository.fetchKittyDetails(any())).thenReturn(kitty) viewModel.requestKittyDetails("Fluffy") }a }a Architecture Example
107. @p_szklarska @RunWith(MockitoJUnitRunner::class) class MainViewModelTest { @Rule @JvmField val rule = InstantTaskExecutorRule() @Mock private lateinit var observer: Observer<Kitty> @Mock private lateinit var repository: KittyRepository @InjectMocks private lateinit var viewModel: MainViewModel private val kitty = Kitty("Fluffy", 5) @Test fun `observer is notified when kitty details are requested`() { viewModel.kittyDetails.observeForever(observer) whenever(repository.fetchKittyDetails(any())).thenReturn(kitty) viewModel.requestKittyDetails("Fluffy") verify(observer).onChanged(kitty) }a }a Architecture Example
108. @p_szklarska Resources Android Architecture Documentation: https://developer.android.com/topic/libraries/ architecture/index.html Guide To App Architecture: https://developer.android.com/topic/libraries/ architecture/guide.html Google Samples Repository: https://github.com/googlesamples/android-architecture- components Medium series about Architecture Components: https://medium.com/@pszklarska
109. @p_szklarska Thanks! Questions?