如何正确使用视图模型中的流？

在我的 Android 应用中，我从 Room 获取数据并将其显示在地图上。我遇到了这两种获取数据的视图模型方法。

哪一个是更有效且更好的方法？

目前，我正在使用第二种方法获取数据。它工作正常。只是想知道这两者之间有什么区别。

第一种方法：

private val _visibleRegion = MutableStateFlow(defaultVisibleRegion)
private val _zoomLevel = MutableStateFlow(6f)
private val _isFavorite = MutableStateFlow(false)

val mapData: StateFlow<PagingData<MapData>> = combine(
    _visibleRegion,
    _zoomLevel,
    _isFavorite
) { region, zoom, isFav ->
    Triple(region, zoom, isFav)
}.flatMapLatest { (region, zoom, isFav) ->
    repo.getDataInBoundsPaged(
        region.southwest.latitude,
        region.northeast.latitude,
        region.southwest.longitude,
        region.northeast.longitude,
        zoom = zoom,
        isFav = isFav
    )
}.stateIn(
    scope = viewModelScope,
    started = SharingStarted.WhileSubscribed(5000),
    initialValue = PagingData.empty()
)

fun updateVisibleRegion(region: LatLngBounds) {
    _visibleRegion.value = region
}

fun updateZoomLevel(zoom: Float) {
    _zoomLevel.value = zoom
}

fun toggleFavorite(isFavorite: Boolean) {
    _isFavorite.value = isFavorite
}

vs 第二种方法：

private val _mapData = MutableStateFlow<PagingData<MapData>>(PagingData.empty())
val mapData: StateFlow<PagingData<MapData>> = _mapData.asStateFlow()

private val defaultVisibleRegion = LatLngBounds(
    LatLng(6.792525080049721, 70.06730787456036),
    LatLng(37.411989227903604, 86.94231156259775)
)

init {
    fetchMapData()
}

fun fetchMapData(
    visibleRegion: LatLngBounds = defaultVisibleRegion,
    zoomLevel: Float = 6f,
    isFavorite: Boolean = false
) {
    viewModelScope.launch {
      
        repo.getDataInBoundsPaged(
            visibleRegion.southwest.latitude,
            visibleRegion.northeast.latitude,
            visibleRegion.southwest.longitude,
            visibleRegion.northeast.longitude,
            zoom = zoomLevel,
            isFav = isFavorite
        )
          
            .cachedIn(viewModelScope)
            .collect {
                _mapData.value = it
             
            }
    }
}