Hilt Di

Procedure

1. Make a Class Injectable

class TextChunkerImpl @Inject constructor() : TextChunker {
    override fun randomExcerpt(text: String, seed: Long): String { … }
}

2. Bind Interface → Implementation

Create or update data/di/DataModule.kt:

@Module
@InstallIn(SingletonComponent::class)
abstract class DataModule {

    @Binds @Singleton
    abstract fun bindTextChunker(impl: TextChunkerImpl): TextChunker

    @Binds @Singleton
    abstract fun bindPromptBuilder(impl: PromptBuilderImpl): PromptBuilder

    @Binds @Singleton
    abstract fun bindQuizGeneratorRepository(
        impl: AiCoreQuizGeneratorRepository,
    ): QuizGeneratorRepository
}

3. Wire a ViewModel

@HiltViewModel
class QuizViewModel @Inject constructor(
    private val repository: QuizGeneratorRepository,
) : ViewModel() { … }

4. Swap in a Fake for Debug Builds

In app/src/debug/java/…/di/DebugDataModule.kt:

@Module
@InstallIn(SingletonComponent::class)
abstract class DebugDataModule {

    @Binds @Singleton
    abstract fun bindQuizGeneratorRepository(
        impl: FakeQuizGeneratorRepository,
    ): QuizGeneratorRepository
}

Exclude the release module from debug: annotate DataModule with @Module(…) and declare separate source sets, or use replaces on the debug module.

5. Application Class

@HiltAndroidApp
class QuizzerApplication : Application()

Register in AndroidManifest.xml:

<application android:name=".QuizzerApplication" … />

Key Dependencies

// build.gradle.kts (app) — prefer version catalog
implementation(libs.hilt.android)
ksp(libs.hilt.compiler)

// plugins block
alias(libs.plugins.hilt)
alias(libs.plugins.ksp)