Destroy boilerplate code with Android Architecture Components

This talks goal is for anyone which knows Android or has programmed for Android and never used Android Architecture Components. It's a small introduction with a small "how-to" for each Android Architecture Components. At the end, a small comparison between 3 of the most used patterns in Android.

Transcript

1. Destroy boilerplate code with Android Architecture Components
2. Stavro Xhardha Android Engineer @iKons @suspendingfunction
3. Android JetPack
4. AppCompat Support library for Android visual elements.
5. Android KTX Kotlin extension for Android. sharedPreferences .edit() .putBoolean("key", value) .apply() sharedPreferences.edit { putBoolean("key", value) } //Under the hood: inline fun SharedPreferences.edit( commit: Boolean = false, action: SharedPreferences.Editor.() -> Unit)
6. MultiDex - APK Extend 64K methods - MultiDex saves the day
7. Testing - Unit testing - Instrumentation testing - Real device testing - UI Tests, Room etc. - E2E testing
8. UI - Animation and Transitions - Auto, TV & wear - Emoji - Fragment - Layout - Palette
9. Behavior - Download Manager - Media and Playback - ExoPlayer - MediaPlayer - Permissions - Notifications - Sharing - Slices
11. Android Architecture Components - DataBinding - Lifecycles - LiveData - Navigation - Paging - Room - ViewModel - WorkManager Robust app, quick business solutions.
12. DataBinding findViewById<TextView>(R.id.sample_text).apply { text = viewModel.userName } <TextView android:text="@{viewmodel.userName}" />
13. Usage of DataBinding android { ... dataBinding { enabled = true } } <layout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto"> <data> <variable name="viewmodel" type="com.myapp.data.UserDataViewModel" /> </data> <ConstraintLayout... /> </layout>
14. <layout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto"> <data> <variable name="viewmodel" type="com.myapp.data.UserDataViewModel" /> </data> <ConstraintLayout... /> </layout>
15. <?xml version="1.0" encoding="utf-8"?> <layout xmlns:android="http://schemas.android.com/apk/res/android"> <data> <variable name="viewmodel" type="com.myapp.data.UserDataViewModel"/> </data> <LinearLayout android:orientation="vertical" android:layout_width="match_parent" android:layout_height="match_parent"> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="@{viewmodel.firstName}"/> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="@{viewmodel.lastName}"/> </LinearLayout> </layout>
16. override fun onCreate(savedInstanceState: Bundle?){ super.onCreate(savedInstanceState) viewModel = ViewModelProviders.of(this).get(UserDataViewModel.class) val binding: ActivityMainBinding = DataBindingUtil.setContentView( this, R.layout.activity_main) binding.viewModel = viewModel binding.lifecyclerOwner = this viewModel.loadUser() }
17. Binding Adapters - Set of instructions to embed into view @BindingAdapter("imageUrl", "error") fun loadImage(view: ImageView, url: String, error: Drawable) { Picasso.get().load(url).error(error).into(view) //if else whatever }
18. - Shrinks code - Keeps views super pasive - Angular lookalike - Long compiling time - Need for ViewBinding - JetPack Compose @Composable fun Greeting(name: String) { Text ("Hello $name!") }
19. Lifecycles - Know state of the app - Prevent memory leaks - Manage configuration changes - Fragment Lifecycle - Activity - ViewModels - ….
20. ViewModel - Holds data logic - LifecycleAware - Transfer Data - 1 Activity/Fragment for 1 ViewModel class UserDataViewModel : ViewModel() { override fun onCleared(){ super.onCleared() } }
21. LiveData - Observables - Memory leaks - Manual data observation
22. Implementation class UserDataViewModel : ViewModel() { val _firstName = MutableLiveData<String>() val firstName: LiveData<String> = _firstName init{ _firstName.value = “Ben” } // Rest of the UserDataViewModel… } - Sometimes too much variables
23. Observe LiveData in Fragment viewModel.firstName.observe(this, Observer{ firstNameTextView.text = it })
24. Navigation
25. - Activity with Navigation should be called Passivity! <LinearLayout… > <fragment android:name="androidx.navigation.fragment.NavHostFragment" android:id="@+id/nav_host_fragment" android:layout_width="match_parent" android:layout_height="match_parent" app:defaultNavHost="true" app:navGraph="@navigation/nav_graph"/> </LinearLayout>
26. viewTransactionsButton.setOnClickListener { view -> //Go to desired destination view.findNavController().navigate(R.id.viewTransactionsAction) } //Go back to desired destination view.findNavController().popBackStack(R.id.homeFragment, false) //mind the backstack
27. Room - Abstraction Layer over SQLite - Super easy to configure - Available for RxJava - Available for Kotlin Coroutines
28. @Database( entities = [User::class, Customer::class], version = 1, exportSchema = false ) abstract class MyDatabase : RoomDatabase() { abstract fun userDao(): UserDao } @Dao interface UserDao{ @Query("SELECT * FROM users") suspend fun selectAllUsers(): List<User> }
29. @Entity(tableName = "users") data class Name( @ColumnInfo(name = "user_name") val firstName: String, @ColumnInfo(name = “last_name”) val lastName: String )
30. Configuration Room.databaseBuilder( mContext, MyDatabase::class.java, DATABASE_NAME ).build()
31. Paging Before - Scenario: Retreive data from network/database - Programatically check if reached end of the list - Remake the api/database call if reached the end, holding reference to the key - Load++
32. Paging Library - Library does all for you - Support for RxJava - Handle request/response with livedata PagedList.Config.Builder() .setPageSize(INITIAL_PAGE_SIZE) .setEnablePlaceholders(false) .build() Room with Paging library @Query("SELECT * FROM persons") fun getAllPaged(): DataSource.Factory<Int, Person>
33. class GalleryDataSource @Inject constructor(val mApi: MyApi) : PageKeyedDataSource<Int, UnsplashResult>(){ override fun loadBefore(params: LoadParams<Int>, callback: LoadCallback<Int, UnsplashResult>) {} override fun loadAfter(params: LoadParams<Int>, callback: LoadCallback<Int, UnsplashResult>) { } override fun loadInitial(params: LoadInitialParams<Int>, callback: LoadInitialCallback<Int, UnsplashResult>) { } } //Adapter class: class GalleryAdapter() : PagedListAdapter<UnsplashResult, GalleryAdapter.GalleryViewHolder>(DIFF_UTIL_GALLERY)
34. class GalleryDataSourceFactory @Inject constructor(private val galleryDataSource: GalleryDataSource) : DataSource.Factory<Int, UnsplashResult>(){ override fun create(): DataSource<Int, UnsplashResult> { mGalleryDataSouce = galleryDataSource sourceLiveData.postValue(mGalleryDataSouce) return galleryDataSource } }
35. WorkManager - A mix between JobSceduler and BroadCastReceiver - Simple implementation - Constraints - No need to worry about reboot - Failure is managed - No need to register to manifest
36. class PersonalWorkManager(val context: Context, parameters: WorkerParameters) : Worker(context, parameters){ override suspend fun doWork(): Result = Result.success() //or Result.failure() or Result.retry() } val constraints = Constraints.Builder() .setRequiredNetworkType(NetworkType.CONNECTED) .build() val compressionWork = OneTimeWorkRequestBuilder<PersonalWorkManager>() .setConstraints(constraints) .build() WorkManager.getInstance().enqueue(compressionWork)
37. Add more into Android - Retrofit & OkHttp - Dagger2 - RxJava2 or Kotlin Coroutines - Picasso - Mockito/Mockito Android - Junit4 (or Junit5) - AndroidJunit4 - MockWebServer
38. Right architecture for Android - MVI - MVP - MVVM
39. Questions….