Dependency injection with Hilt in Android Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to annotate the Application class for Hilt.

Android Kotlin

@[1]
class MyApp : Application() {
    override fun onCreate() {
        super.onCreate()
    }
}

Drag options to blanks, or click blank then click option'

A@Inject

B@HiltAndroidApp

C@AndroidEntryPoint

D@Module

Attempts:

3 left

💡 Hint

Common Mistakes

Using @Inject instead of @HiltAndroidApp on the Application class.

Forgetting to annotate the Application class at all.

The @HiltAndroidApp annotation tells Hilt to generate components for dependency injection in the Application class.

2fill in blank

medium

Complete the code to inject a dependency into an Android Activity using Hilt.

Android Kotlin

@AndroidEntryPoint
class MainActivity : AppCompatActivity() {
    @[1]
    lateinit var repository: UserRepository

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
    }
}

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A@Module

B@Provides

C@Inject

D@Singleton

Attempts:

3 left

💡 Hint

Common Mistakes

Using @Provides instead of @Inject for field injection.

Not annotating the Activity with @AndroidEntryPoint.

The @Inject annotation tells Hilt to provide the dependency instance into the field.

3fill in blank

hard

Fix the error in the Hilt module by completing the annotation to provide a singleton instance.

Android Kotlin

@Module
@InstallIn(SingletonComponent::class)
object AppModule {
    @Provides
    @[1]
    fun provideDatabase(@ApplicationContext context: Context): AppDatabase {
        return Room.databaseBuilder(context, AppDatabase::class.java, "app_db").build()
    }
}

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ASingleton

BProvides

CInject

DBinds

Attempts:

3 left

💡 Hint

Common Mistakes

Using @Provides alone without @Singleton for shared instances.

Using @Inject on provider functions.

The @Singleton annotation ensures that Hilt provides a single instance of the database throughout the app.

4fill in blank

hard

Fill both blanks to create a Hilt module that binds an interface to its implementation.

Android Kotlin

@Module
@InstallIn(SingletonComponent::class)
abstract class RepositoryModule {
    @Binds
    abstract fun bindUserRepository(
        [1]: UserRepositoryImpl
    ): [2]
}

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AuserRepositoryImpl

BUserRepository

CuserRepository

DUserRepositoryImpl

Attempts:

3 left

💡 Hint

Common Mistakes

Using the interface name as the parameter name.

Swapping the parameter and return types.

The function parameter name is usually camelCase of the implementation class, and the return type is the interface to bind.

5fill in blank

hard

Fill all three blanks to create a Hilt module that provides a Retrofit instance with a base URL.

Android Kotlin

@Module
@InstallIn(SingletonComponent::class)
object NetworkModule {
    @Provides
    @Singleton
    fun provideRetrofit(): Retrofit {
        return Retrofit.Builder()
            .baseUrl([1])
            .addConverterFactory([2])
            .client([3])
            .build()
    }
}

Drag options to blanks, or click blank then click option'

A"https://api.example.com/"

BGsonConverterFactory.create()

CScalarsConverterFactory.create()

DOkHttpClient()

Attempts:

3 left

💡 Hint

Common Mistakes

Using a wrong URL format without quotes.

Using the wrong converter factory.

Confusing client creation with converter factory.

The baseUrl is a string URL, the converter factory is GsonConverterFactory, and OkHttpClient is often used but here the blank is for the client setup (though not shown in code, the third blank is for client).