ericntd

val viewState = MutableLiveData<ViewState>()

init {
    viewState.value = ViewState.Loading
    interactor.getProfile().let { getProfileState ->
        when (getProfileState) {
            is GetProfileInteractor.State.Success -> {
                // render updates on UI
                viewState.value = ViewState.ProfileLoaded(getProfileState.profile)
            }

ericntd

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)

    setUpObservation()
}

private fun setUpObservation() {
    viewModel.viewState.observe(this, Observer { state ->
        when (state) {

ericntd

val viewState = MutableLiveData<ViewState>()
val actionState = SingleLiveEvent<ActionState>() // each value emit only once

init {
    viewState.value = ViewState.Loading
    interactor.getProfile().let { getProfileState ->
        when (getProfileState) {
            is GetProfileInteractor.State.Success -> {
                // render updates on UI
                viewState.value = ViewState.ProfileLoaded(getProfileState.profile)

ericntd

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)

    setUpObservation()
}

private fun setUpObservation() {
    viewModel.viewState.observe(this, Observer { state ->
        when (state) {

ericntd

class ProfileViewModel(val interactor: GetProfileInteractor) : ViewModel() {
    private val viewState = MutableLiveData<ViewState>()
    private val actionState = SingleLiveEvent<ActionState>()
    val viewStateReadOnly: LiveData<ViewState> = viewState as LiveData<ViewState>
    val actionStateReadOnly: LiveData<ActionState> = actionState as LiveData<ActionState>
  ...
}

ericntd

override fun onActivityResult(...) {
    // process success/ failure, extract data
    viewModel.onActivityResult(...)
} 
fun onRefreshed() {
    viewModel.onRefreshed()
}
fun onSomeButtonClicked() {
    viewModel.onSomeButtonClicked()
}

ericntd

private val viewState = MutableLiveData<ViewState>()
private var someUsefulVariable: Int? = null // mutable!

init {
  doStep1()
  //...
  .doStepK()
  .map { stepKResult -> 
        someUsefulVariable = ... // derived from stepKresult
        return@map processData(stepKResult, someUsefulVariable)

ericntd

val inputSubject = PublishSubject.create<String>() // immutable!
val inputSubjectReadOnly = inputSubject.debounce(500L, TimeUnit.MILLISECONDS)
val someViewModel = SomeViewModel(inputSubjectReadOnly, ...)

override fun onSomeButtonClicked(...) {
     // process success/ failure, extract data
     inputSubject.onNext(data) // emit to input stream ViewModel consumes
}

ericntd

class SomeViewModel(val inputStream: Observable<SomeDataType>, ...) {
private val viewState = MutableLiveData<ViewState>()
  
init {
  doStep1()
  //...
  .doStepK()
  .zipWith(inputStream) // combine/ merge 2 streams into 1 using Pair
  .map { pair ->
        val stepKresult = pair.first

ericntd

class SomeActivity: AppCompatActivity {
  override fun onCreate(savedInstanceState: Bundle?) {
    //...

    val profileRepository = ProfileRepository(...)
    val someRepository = SomeRepository(...)
    val somePresenter = SomePresenter(profileRepository, someRepository)
    somePresenter.doSomeWork()
  }
}