How is dependency lifecycle management implemented in the Hilt library?

In the Hilt library, dependency lifecycle management is performed using annotations that bind objects to specific Android lifecycle components (such as Application, Activity, Fragment).

Main points:

• Scopes — annotations like @Singleton, @ActivityScoped, @FragmentScoped define how long an object will exist. For example, @Singleton creates a single instance for the entire application, while @ActivityScoped lasts for the lifetime of an Activity.

• Hilt components — are automatically created for different lifecycle levels (ApplicationComponent, ActivityComponent, etc.), and dependencies bound to these components live as long as the component.

• Automatic injection — Hilt manages the creation and destruction of dependencies according to the Android component lifecycle, reducing the risk of memory leaks and simplifying code.

Example:

@Singleton
class Repository @Inject constructor() {
    // Lives at the application level
}

@ActivityScoped
class ActivityHelper @Inject constructor() {
    // Lives at the Activity level
}

@AndroidEntryPoint
class MainActivity : AppCompatActivity() {
    @Inject lateinit var repository: Repository
    @Inject lateinit var helper: ActivityHelper
}

Thus, Hilt binds the lifecycle of dependencies to the lifecycle of Android components through scopes and components, ensuring proper creation and destruction of objects.