Single Live Event Stream Sample

gistfile1.txt

class MainViewModel : ViewModel() {

    sealed class Event {
        object NavigateToSettings: Event()
        data class ShowSnackBar(val text: String): Event()
        data class ShowToast(val text: String): Event()
    }

    private val eventChannel = Channel<Event>(Channel.BUFFERED)
    val eventsFlow = eventChannel.receiveAsFlow()

    init {
        viewModelScope.launch {
            eventChannel.send(Event.ShowSnackBar("Sample"))
            eventChannel.send(Event.ShowToast("Toast"))
        }
    }

    fun settingsButtonClicked() {
        viewModelScope.launch {
            eventChannel.send(Event.NavigateToSettings)
        }
    }
}

class MainFragment : Fragment() {

    companion object {
        fun newInstance() = MainFragment()
    }

    private val viewModel by viewModels<MainViewModel>()
    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View {
        return inflater.inflate(R.layout.main_fragment, container, false)
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        // Note that I've chosen to observe in the tighter view lifecycle here. 
        // This will potentially recreate an observer and cancel it as the
        // fragment goes from onViewCreated through to onDestroyView and possibly
        // back to onViewCreated. You may wish to use the "main" lifecycle owner
        // instead. If that is the case you'll need to observe in onCreate with the
        // correct lifecycle.
        viewModel.eventsFlow
                .onEach {
                    when (it) {
                        MainViewModel.Event.NavigateToSettings -> {}
                        is MainViewModel.Event.ShowSnackBar -> {}
                        is MainViewModel.Event.ShowToast -> {}
                    }
                }
                .observeInLifecycle(viewLifecycleOwner)
    }

}