Dagger ‐ Injecting values at runtime by component factory

Contents
Observations
Output
Code

Observations

• Another way of injecting values dynamically is using the component factory.
• If we use a component factory we explicitly need to specify how the component is being constructed.
• If any dynamic values are passed, It has to be passed here.

Output

Sending is successfully via Message Service with tag Pikachu

Code

Contents
implementations
Modules
Components
Activity

implementations

NotificationService.kt

interface NotificationService {
    fun sendTo(to:String,from:String,subject:String,body:String)
}

EmailService.kt

class EmailService : NotificationService {
    override fun sendTo( to: String, from: String, subject: String, body: String ) {
        PrintUtils.printLog("Sending is successfully via Email Service")
    }
}

MessageService.kt

class MessageService @Inject constructor( private val messageTag:String) : NotificationService {
    override fun sendTo( to: String, from: String, subject: String, body: String ) {
        PrintUtils.printLog("Sending is successfully via Message Service with tag $messageTag")
    }
}

Modules

MessageServiceModule.kt

@Module
@DisableInstallInCheck
class MessageServiceModule {

    @Provides
    fun provideMessageService(messageTag: String) : NotificationService {
        return MessageService(messageTag)
    }

}

Components

MessageServiceComponent.kt

@Component(modules = [MessageServiceModule::class])
interface MessageServiceComponent {

    fun getMainService() : MainService

    @Component.Factory
    interface Factory{
        fun create(
            @BindsInstance messageTag:String
        ) : MessageServiceComponent
    }

}

Activity

MyActivity.kt

class MyActivity : AppCompatActivity() {

    private lateinit var binding: ActivityDaggerConceptsBinding

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityDaggerConceptsBinding.inflate(layoutInflater)
        setContentView(binding.root)
        setOnClickListener()
    }

    private fun setOnClickListener() {
        binding.apply {
            // Injecting values at runtime - Using Component
            injectValAtRuntimeComponentFactoryId.setOnClickListener {
                val comp = DaggerMessageServiceComponent
                    .factory().create("Pikachu").getMainService()
                comp.initiateAction()
            }
        }
    }
}