【ANDROID STUDIO】Singleton With Dagger

 package com.example.dagger

import android.util.Log
import javax.inject.Inject
import javax.inject.Singleton


@Singleton
class SmartPhone @Inject constructor(val battery: Battery, val simCard: SIMCard, val memoryCard: MemoryCard) {

    init {
        battery.getPower()
        simCard.getConnection()
        memoryCard.getSpaceAvailablity()
        Log.i("MYTAG", "SmartPhone Constructed")
    }

    fun makeACallWithRecording() {
        Log.i("MYTAG", "Calling.....")
    }
}

package com.example.dagger

import dagger.Component
import javax.inject.Singleton

@Singleton
@Component(modules = [MemoryCardModule::class, NCBatteryModule::class])
interface SmartPhoneComponent {
     fun inject(mainActivity: MainActivity)
}
package com.example.dagger

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import dagger.internal.InjectedFieldSignature
import javax.inject.Inject

class MainActivity : AppCompatActivity() {

    @Inject
    lateinit var smartPhone: SmartPhone
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        (application as SmartPhoneApplication).smartPhoneComponent.inject(this)
        smartPhone.makeACallWithRecording()

    }
}