Hi everyone how do you use coroutines to tackle with the Sin

Question

Hi everyone how do you use coroutines to tackle with the SingleLiveEvent I ve tried the code below but when rotating the device the latest value is displayed i want the value to be consumed only once just as SingleLiveEvent is ```protected val loadingState = BroadcastChannel lt Boolean gt Channel BUFFERED val actionReceiver = loadingState asFlow ```

Shalom Halbert · Answer

`SharedFlow` is what you want to use

Shalom Halbert · Answer

Adam Powell · Answer

If you want only a single consumer to receive something you send use ```val loadingChannel = Channel lt Boolean gt Channel BUFFERED val loadingFlow = loadingChannel receiveAsFlow ```

Adam Powell · Answer

send to `loadingChannel` and observe using `loadingFlow`

FunkyMuse · Answer

I tried that but when the rotation happens the last value is emitted

FunkyMuse · Answer

I even tried consumeAsFlow since it happens only once

Adam Powell · Answer

If you use `Channel receiveAsFlow` then no value will be emitted more than once Are you sure your other code isn t sending to the channel more than once

FunkyMuse · Answer

I ll check that and post the code if i don t find any solution I m literally trying to replace SingleLiveEvent

Adam Powell · Answer

it s good to replace SingleLiveEvent it s a workaround for a problem that doesn t exist with coroutines channels flows slightly smiling face

Adam Powell · Answer

but SingleLiveEvent encourages some other antipatterns around working with state and events You may need to resolve those to move forward in an elegant way if they ve crept into your codebase

FunkyMuse · Answer

My use case is this User clicks download Download event success or fail update ui only once Which I ve habdled with single live event before

Adam Powell · Answer

yes this is where clearly separating state and events helps clarify the design Events happen only once State is updated by events and current state can be observed at any time as many times as desired Reacting to state updates is always idempotent so there s no need to think of it as updating UI only once UI update observers update the UI to match the state with no other side effects Any one time side effects of the download complete event should happen as part of observing the one time download complete event and setting the download completed state used by the UI updaters

FunkyMuse · Answer

In my view model i had val loadingChannel = Channel lt Boolean gt Channel BUFFERED val loadingFlow = loadingChannel receiveAsFlow And in my fragment viewLifecycleOwner lifecycleScope launcWhenResumed viewModel loadingFlow collect Some logic here Inside my logic i didn t receive anything I tried loadingChannel offer true and false Am I doing something wrong

Adam Powell · Answer

did you check that the `launchWhenResumed` block runs as expected before the `collect` call begins

FunkyMuse · Answer

Yes it runs since i have another StateFlow collecting the list

FunkyMuse · Answer

Found the problem

FunkyMuse · Answer

This did not work

FunkyMuse · Answer

whilst this did work

FunkyMuse · Answer

```val Fragment viewCoroutineScope get = viewLifecycleOwner lifecycle coroutineScope```

FunkyMuse · Answer

weird both are suspending functions btw

Oleksandr Balan · Answer

I believe it s due to `collectSubtitles` is blocking I bet you start to collect a `Flow` there slightly smiling face

FunkyMuse · Answer

yes i did

FunkyMuse · Answer

how do i fix it

FunkyMuse · Answer

if i use ``` onEach launchIn scope ``` and put it inside the onResumed block would it be called in onResume since it s launched in the scope with launchIn

Adam Powell · Answer

You can wrap each of the two calls that you want to run concurrently in their own `launch` inside a single `launchWhenResumed`

Adam Powell · Answer

``` launchWhenResumed launch collectSubtitles launch handleDownloadStatus ```

FunkyMuse · Answer

That s more than i needed it s clear to me now thanks Adam beer

Oleksandr Balan · Answer

But there is no big difference between ```scope launchWhenResumed launch collectSubtitles launch handleDownloadStatus ``` and ```scope launchWhenResumed collectSubtitles scope launchWhenResumed handleDownloadStatus ```

Adam Powell · Answer

the former is a bit more efficient