Approach 1

Approach 2

ViewModel by viewModels()

class Preferences(private val sharedPreferences: SharedPreferences) {
    private companion object {
        private const val GENERATED_LEVEL_INFO_SEEN_KEY =
                "generatedLevelInfoSeenKey"

       // ...
    }

    var generatedLevelInfoSeen by BooleanPreference(
            GENERATED_LEVEL_INFO_SEEN_KEY, false)

    // ...

    private inner class BooleanPreference(
            private val key: String,
            private val default: Boolean) {

        operator fun getValue(thisRef: Preferences, property: KProperty<*>) =
                sharedPreferences.getBoolean(key, default)

        operator fun setValue(thisRef: Preferences, property: KProperty<*>, value: Boolean) =
                sharedPreferences.edit { putBoolean(key, value) }
    }
}

ViewModel/Repository

fun getData() = liveData {
    val a = getFromDB()
    emit(a)
    val b = getFromNetwork()
    emit(b)
}

View

viewModel.getData().observe(this, Observer{
    // do ui stuff
})

liveData {}

getData()

MediatorLiveData

liveData {}

ViewModel

LifecycleObserver

ViewModel

View

ViewModel

class Car() :MovingObjects{
    val carParts = CarParts()
    val carFunctionalities =CarFunctionalities()
    
}

class CarParts():MovingObjects(){
        fun engine(): Engine
        fun wheel(): Wheel
        fun doors():Doors

    } 
}
class CarFunctionalities():MovingObjects{
    fun switchOn()
    fun maxVelocity(): Int
}

class MainViewActVM(val repository: AppRepository) : ViewModel(){
}

//...Our Activity/Fragment
private val mainViewActVM: MainViewActVM by lazy {
ViewModelProviders.of(this, ReminderViewActVM.Factory(AppRepository.getInstance(this))).get(MainViewActVM::class.java)

class MainViewActVM(application: Application) : AndroidViewModel(application) {
    private val repository: AppRepository = AppRepository.getInstance(application)
.....
}