Nineworlds Serenity Android Serenity Android

Dependency Injection with Toothpick

Scoping Standards

Serenity uses hierarchical scopes to manage object lifecycles.

• APPLICATION_SCOPE: Global singletons (Repositories, API Clients, Preferences).
• Activity/Fragment Scopes: Lifecycle-bound dependencies.

Injection Patterns

Constructor Injection (Preferred)

Use @InjectConstructor to allow Toothpick to automatically instantiate and inject dependencies.

@InjectConstructor
class MyRepository(private val api: MyApi) { ... }

Provider-Based Injection

Useful for lazy initialization or breaking circular dependencies.

@Inject
lateinit var presenterProvider: Provider<MainPresenter>

Manual Injection

Used in components where constructor injection isn't possible (e.g., legacy classes, some base classes).

init {
    Toothpick.inject(this, Toothpick.openScope(InjectionConstants.APPLICATION_SCOPE))
}

Module Configuration

Bindings are defined in Module classes.

class MyModule : Module() {
    init {
        bind(MyService::class.java).to(MyServiceImpl::class.java).singleton()
        bind(MyRepository::class.java).toInstance(myRepositoryInstance)
    }
}

Integration in Activities/Fragments

Extend InjectingActivity or InjectingMvpActivity to have scopes managed automatically.

class MyActivity : InjectingActivity() {
    @Inject lateinit var myService: MyService
    
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        // Injection happens in super.onCreate()
    }
}

Source: NineWorlds/serenity-android — distributed by TomeVault.