Android 如何观察协同程序流的ContentProvider更改

我有一个通过内容提供者从数据库获取数据的流程

fun getDataFlow(): Flow<Result> {
    return flow {
      emit(Result.Loading)

      // fetchAll() is the method to fetch data via contentResolover.query()
      val results = fetchAll()
      emit(Result.Success(categories))
    }.catch { e ->
      emit(Result.Error(e))
    }
  }

val contentObserver = object : ContentObserver(null) {
      override fun onChange(selfChange: Boolean) {
        super.onChange(selfChange)
      }
    }