[Kotlin](used dagger) MessagingServices extends FirebaseMessageService to get the FCM Device Token when the app is installed for the first time.

BaseApplication.kt

class BaseApplication: DaggerApplication() {

    @Inject
    lateinit var mSharedPrefs: SharedPreferences

    override fun applicationInjector(): AndroidInjector<out DaggerApplication> {
        return DaggerAppComponent.factory().create(this)
    }

    override fun onCreate() {
      super.onCreate()

      // important
      FirebaseApp.initializeApp(this)

      FirebaseInstallations.getInstance().id.addOnCompleteListener { task: Task<String?> ->
        if (task.isSuccessful) {
            val token = task.result
            Log.e("token ---->>", token!!)

            val mEditor = mSharedPrefs.edit()
            mEditor.putString(AppConstants.FCM_TOKEN, token)
            mEditor.apply()

        }
      }
    }
}

DaggerFirebaseService.kt

// if you don't want to use dagger just extend the MessagingServices directly with FirebaseMessagingService()
abstract class DaggerFirebaseService : FirebaseMessagingService() {
    override fun onCreate() {
        AndroidInjection.inject(this)
        super.onCreate()
    }
}

MessagingServices.kt

class MessagingServices: DaggerFirebaseService() {

    override fun onNewToken(token: String) {
        // whatever you want
    }

    override fun onMessageReceived(remoteMessage: RemoteMessage) {
      super.onMessageReceived(remoteMessage)
      // whatever you want
    }
}

Click here for the Java (without dagger) version