SharedSingletonSampleDagger.kt

import dagger.Component
import javax.inject.Inject
import javax.inject.Singleton

// ===== Shared Singleton =====

@Singleton
class SharedService @Inject constructor() {
    val id = System.identityHashCode(this)
}

// ===== Feature One =====

class FeatureOne {
    @Inject
    lateinit var sharedService: SharedService

    fun printId() = println("FeatureOne sees: ${sharedService.id}")
}

// ===== Feature Two =====

class FeatureTwo {
    @Inject
    lateinit var sharedService: SharedService

    fun printId() = println("FeatureTwo sees: ${sharedService.id}")
}

// ===== Shared Component =====

@Singleton
@Component
interface SharedComponent {
    fun sharedService(): SharedService
}

// ===== Feature One Component (зависит от SharedComponent) =====

@Component(dependencies = [SharedComponent::class])
interface FeatureOneComponent {
    fun inject(target: FeatureOne)
}

// ===== Feature Two Component (зависит от SharedComponent) =====

@Component(dependencies = [SharedComponent::class])
interface FeatureTwoComponent {
    fun inject(target: FeatureTwo)
}

// ===== MAIN =====

fun main() {
    val sharedComponent = DaggerSharedComponent.create()

    val featureOneComponent = DaggerFeatureOneComponent.builder()
        .sharedComponent(sharedComponent)
        .build()

    val featureTwoComponent = DaggerFeatureTwoComponent.builder()
        .sharedComponent(sharedComponent)
        .build()

    val featureOne = FeatureOne()
    val featureTwo = FeatureTwo()

    featureOneComponent.inject(featureOne)
    featureTwoComponent.inject(featureTwo)

    featureOne.printId()
    featureTwo.printId()
}