GDG Location 

GDG Location What is DI ? 

GDG Location • Reduces the boilerplate code • Makes our code reusable and clean • Make testing easier • Ease of refactoring DI advantages 

GDG Location // No Dependency Injection class Car { private val engine = Engine() fun start() {...} } 

GDG Location // No Dependency Injection class Car { private val engine = Engine() fun start() {...} } fun main() { val car = Car() car.start() } 

GDG Location // With Dependency Injection class Car(private val engine: Engine) { fun start() {...} } 

GDG Location // With Dependency Injection class Car(private val engine: Engine) { fun start() {...} } fun main() { val engine = Engine() val car = Car(engine) car.start() } 

GDG Location DI in Android Many ways to do it... Kodein Koin Dagger ... 

GDG Location Hilt 

GDG Location Hilt ● Standardize DI in Android ● Build on top of Dagger ● Tooling Support ● AndroidX Extensions 

GDG Location Setup buildscript { ... dependencies { ... classpath 'com.google.dagger:hilt-android-gradle-plugin:2.28-alpha' } } build.gradle (project) 

GDG Location Setup apply plugin: 'kotlin-kapt' apply plugin: 'dagger.hilt.android.plugin' //... dependencies { implementation "com.google.dagger:hilt-android:2.28-alpha" kapt "com.google.dagger:hilt-android-compiler:2.28-alpha" } build.gradle (app) 

GDG Location Hilt annotations ● @HiltAndroidApp ● @Inject ● @AndroidEntryPoint ● @InstallIn ● ... 

GDG Location @HiltAndroidApp class CarApplication : Application() 

GDG Location class Car @Inject constructor() { fun start() { } } 

GDG Location class Car @Inject constructor() { fun start() { } } @AndroidEntryPoint class CarActivity: AppCompatActivity(){ } 

GDG Location class Car @Inject constructor() { fun start() { } } @AndroidEntryPoint class CarActivity: AppCompatActivity(){ @Inject lateinit var car: Car } 

GDG Location class Car @Inject constructor() { fun start() { } } @AndroidEntryPoint class CarActivity: AppCompatActivity(){ @Inject lateinit var car: Car override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) car.start() } } 

GDG Location Components 

GDG Location Components 

GDG Location Hilt Module When Interface 3rd party lib Configuration 

GDG Location class Car @Inject constructor( private val db: CarDB ) { ... } 

GDG Location @Module @InstallIn(ApplicationComponent::class) object DataModule{ @Provides fun provideCardDB(@ApplicationContext context: Context) = Room.databaseBuilder(context,CarDB::class.java,"car.db") .build() } 

GDG Location @Module @InstallIn(ApplicationComponent::class) object DataModule{ @Provides fun provideCardDB(@ApplicationContext context: Context) = Room.databaseBuilder(context,CarDB::class.java,"card.db") .build() } 

GDG Location @Module @InstallIn(ApplicationComponent::class) object DataModule{ @Provides @Singleton fun provideCardDB(@ApplicationContext context: Context) = Room.databaseBuilder(context,CarDB::class.java,"card.db") .build() } 

GDG Location AndroidX Extensions class CarViewModel @ViewModelInject constructor( private val db: CarDB ) : ViewModel() { ... } 

GDG Location AndroidX Extensions class CarViewModel @ViewModelInject constructor( private val db: CarDB ) : ViewModel() { ... } @AndroidEntryPoint class CarActivity0 : AppCompatActivity() { val viewModel: CarViewModel by ViewModels() override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) viewModel.start() } } 

GDG Location Resources ● Using Hilt in your Android app [https://cutt.ly/3fsTeno] ● Migrating your Dagger app to Hilt [https://cutt.ly/1fsTiU7] 

Thank you!