fabioCollini

class MainActivity : AppCompatActivity() {

    @Inject
    lateinit var viewModelProvider: Provider<MyViewModel>

    private val viewModel by viewModels { viewModelProvider }

    override fun onCreate(savedInstanceState: Bundle?) {
        (application as MyApp).component.inject(this)
        super.onCreate(savedInstanceState)

fabioCollini

inline fun <reified VM : ViewModel> AppCompatActivity.viewModels(
        crossinline producer: () -> Provider<VM>
): Lazy<VM> =
    viewModels {
        object : ViewModelProvider.Factory {
            override fun <T : ViewModel> create(c: Class<T>) = 
                producer().get() as T
        }
    }

fabioCollini

class MainActivity : AppCompatActivity() {

    @Inject
    lateinit var dependency: Dependency

    override fun onCreate(savedInstanceState: Bundle?) {
        (application as MyApp).component.inject(this)
        super.onCreate(savedInstanceState)
        //...
    }

fabioCollini

@Module
object MyModule {
    @Singleton
    @Provides
    fun provideCache(
        databaseCache: Provider<DatabaseCache>,
        inMemoryCache: Provider<InMemoryCache>
    ): Cache {
        return if (useInMemoryCache())
            inMemoryCache.get()

fabioCollini

@Module
object MyModule {
    @Singleton
    @Provides
    fun provideCache(
        databaseCache: DatabaseCache,
        inMemoryCache: InMemoryCache
    ): Cache {
        return if (useInMemoryCache())
            inMemoryCache

fabioCollini

@Module
interface MyModule {
    @Binds
    fun bindsCache(impl: DatabaseCache): Cache

    companion object {
        @Provides
        fun provideApi(): Api {
            return createApiImplementationUsingRetrofit()
        }

fabioCollini

@Module
object MyApiModule {
    @Singleton
    @Provides
    fun provideApi(): Api {
        return createApiImplementationUsingRetrofit()
    }
}

fabioCollini

@Module
interface MyModule {
    @Binds
    fun bindsCache(impl: DatabaseCache): Cache
}

fabioCollini

@Module
object MyModule {
    @Provides
    fun provideCache(impl: DatabaseCache): Cache = impl
}

fabioCollini

class DatabaseCache @Inject constructor(
    private val database: Database
) : Cache {
    override fun load(): String? = database.executeQuery()
}