Hilt DI Deep Dive

#Building a Weather App. This app will display the current weather information for a given location. Here’s how you might structure it using MVVM and Hilt:

• Create Application Instance: Annotate your Application class with @HiltAndroidApp.

@HiltAndroidApp class WeatherApplication : Application() { … }

• Create Activity: Annotate your Activity class with @AndroidEntryPoint. This will be the main activity displaying weather information.

@AndroidEntryPoint class MainActivity : AppCompatActivity() { … }

• Create ViewModel: Implement the ViewModel class. This ViewModel will handle the logic for fetching the weather data and updating the UI.

class WeatherViewModel @Inject constructor(private val repository: WeatherRepository) : ViewModel() { // LiveData to hold the weather data val weatherData: LiveData = repository.weatherData }

• Create Offline Repository (with Room): Implement a Room Database for offline data storage. This will store the weather data locally.

@Database(entities = [Weather::class], version = 1) abstract class WeatherDatabase : RoomDatabase() { abstract fun weatherDao(): WeatherDao }

• Create Online Repository (with Retrofit): Implement a Retrofit interface for online data fetching. This will fetch the weather data from a weather API.

interface WeatherService { @GET(“weather”) suspend fun getWeather(@Query(“q”) location: String): Response }

• Inject Dependencies with Hilt: Use Hilt for dependency injection. This will provide the necessary dependencies to your classes.

@Module @InstallIn(SingletonComponent::class) object AppModule { @Provides fun provideWeatherService(): WeatherService = Retrofit.Builder() .baseUrl(“https://api.openweathermap.org/data/2.5/”) .addConverterFactory(GsonConverterFactory.create()) .build() .create(WeatherService::class.java)

@Provides
fun provideDatabase(@ApplicationContext appContext: Context): WeatherDatabase = Room.databaseBuilder(
    appContext,
    WeatherDatabase::class.java,
    "weather_database"
).build()

@Provides
fun provideWeatherDao(db: WeatherDatabase): WeatherDao = db.weatherDao() }

This is a simplified example. For a more detailed explanation, you can refer to the articles I found. Happy coding! 🚀