ValeryPonomarenko

class SomeApplication : Application() {

    private lateinit var appComponent: AppComponent

    private var featureComponent: FeatureComponent? = null

    override fun onCreate() {
        super.onCreate()
        appComponent = DaggerAppComponent.builder()
            .someModule(SomeModule())

ValeryPonomarenko

interface IHasComponent {
    fun getComponent(): Any
    fun getComponentKey(): String = javaClass.toString()
}

ValeryPonomarenko

internal class ComponentsStore {
    private val componentsForView = mutableMapOf<String, Any>()

    fun isExist(key: String): Boolean =
        componentsForView.containsKey(key)

    fun add(key: String, component: Any) {
        componentsForView[key] = component
    }

ValeryPonomarenko

class ComponentNotFoundException : Throwable("Component was not found")

ValeryPonomarenko

class InjectionManager {
    companion object {
        @JvmStatic val instance = InjectionManager()
    }

    private val componentsStore = ComponentsStore()

    fun init(app: Application) {
        app.registerActivityLifecycleCallbacks(ActivityLifecycleHelper(componentsStore))
    }

ValeryPonomarenko

internal class ActivityLifecycleHelper(
    private val componentsStore: ComponentsStore
) : Application.ActivityLifecycleCallbacks {
    override fun onActivityPaused(activity: Activity) {}

    override fun onActivityResumed(activity: Activity) {}

    override fun onActivityStarted(activity: Activity) {}

    override fun onActivityDestroyed(activity: Activity) {

ValeryPonomarenko

internal class FragmentLifecycleHelper(
    private val componentsStore: ComponentsStore
) : FragmentManager.FragmentLifecycleCallbacks() {
    private var isInSaveState = false

    override fun onFragmentStarted(fm: FragmentManager, f: Fragment) {
        super.onFragmentStarted(fm, f)
        isInSaveState = false
    }

ValeryPonomarenko

class SimpleApplication : Application() {
    override fun onCreate() {
        super.onCreate()
        InjectionManager.instance.init(this)
    }
}

ValeryPonomarenko

class FirstFragment : Fragment(), IHasComponent {
    //code...
    
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        InjectionManager.instance.bindComponent<FirstFeatureComponent>(this).inject(this)
    }

    override fun getComponent(): FirstFeatureComponent =
        DaggerFirstFeatureComponent.builder()

ValeryPonomarenko

class SecondFragment : Fragment() {

    //code...

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        InjectionManager.instance.findComponent<AppComponent>().inject(this)
    }
}