StateFlow 및 SharedFlow

class LatestNewsViewModel(     private val newsRepository: NewsRepository ) : ViewModel() {      // Backing property to avoid state updates from other classes     private val _uiState = MutableStateFlow(LatestNewsUiState.Success(emptyList()))     // The UI collects from this StateFlow to get its state updates     val uiState: StateFlow<LatestNewsUiState> = _uiState      init {         viewModelScope.launch {             newsRepository.favoriteLatestNews                 // Update View with the latest favorite news                 // Writes to the value property of MutableStateFlow,                 // adding a new element to the flow and updating all                 // of its collectors                 .collect { favoriteNews ->                     _uiState.value = LatestNewsUiState.Success(favoriteNews)                 }         }     } }  // Represents different states for the LatestNews screen sealed class LatestNewsUiState {     data class Success(val news: List<ArticleHeadline>): LatestNewsUiState()     data class Error(val exception: Throwable): LatestNewsUiState() } 

class LatestNewsActivity : AppCompatActivity() {     private val latestNewsViewModel = // getViewModel()      override fun onCreate(savedInstanceState: Bundle?) {         ...         // Start a coroutine in the lifecycle scope         lifecycleScope.launch {             // repeatOnLifecycle launches the block in a new coroutine every time the             // lifecycle is in the STARTED state (or above) and cancels it when it's STOPPED.             repeatOnLifecycle(Lifecycle.State.STARTED) {                 // Trigger the flow and start listening for values.                 // Note that this happens when lifecycle is STARTED and stops                 // collecting when the lifecycle is STOPPED                 latestNewsViewModel.uiState.collect { uiState ->                     // New value received                     when (uiState) {                         is LatestNewsUiState.Success -> showFavoriteNews(uiState.news)                         is LatestNewsUiState.Error -> showError(uiState.exception)                     }                 }             }         }     } } 

class NewsRemoteDataSource(...,     private val externalScope: CoroutineScope, ) {     val latestNews: Flow<List<ArticleHeadline>> = flow {         ...     }.shareIn(         externalScope,         replay = 1,         started = SharingStarted.WhileSubscribed()     ) } 

// Class that centralizes when the content of the app needs to be refreshed class TickHandler(     private val externalScope: CoroutineScope,     private val tickIntervalMs: Long = 5000 ) {     // Backing property to avoid flow emissions from other classes     private val _tickFlow = MutableSharedFlow<Unit>(replay = 0)     val tickFlow: SharedFlow<Event<String>> = _tickFlow      init {         externalScope.launch {             while(true) {                 _tickFlow.emit(Unit)                 delay(tickIntervalMs)             }         }     } }  class NewsRepository(     ...,     private val tickHandler: TickHandler,     private val externalScope: CoroutineScope ) {     init {         externalScope.launch {             // Listen for tick updates             tickHandler.tickFlow.collect {                 refreshLatestNews()             }         }     }      suspend fun refreshLatestNews() { ... }     ... }