안드로이드 Coroutine Flow - 3 (StateFlow) 코드

 

ViewModel

class CoroutineStateFlowViewModel : ViewModel() {

    // StateFlow
    private val _coroutineData = MutableStateFlow(CoroutineUiState.success(""))
    val coroutineData: StateFlow<CoroutineUiState<String>> = _coroutineData.asStateFlow()

    // ShareFlow
    private val _sharedFlow = MutableSharedFlow<String>(
        replay = 1,
        extraBufferCapacity = 1
    )

    val sharedFlow: SharedFlow<String> = _sharedFlow
        .shareIn(
            scope = viewModelScope,  // viewModelScope로 생명주기 관리
            started = SharingStarted.WhileSubscribed(1000), // 구독자가 없을 때 5초 후 정지
            replay = 1  // 최근 값 1개 재생
        )

    // StateIn
    private val _stateInFlow:StateFlow<String> = makeFlowData().stateIn(
        scope = viewModelScope,           // CoroutineScope
        started = SharingStarted.WhileSubscribed(1000),  // Flow 시작 시점 설정
        initialValue = "Initial State" // 초기 값
    )

    val stateInFlow: StateFlow<String> = _stateInFlow

    fun loadData() {
        viewModelScope.launch {
            try {
                _coroutineData.value = CoroutineUiState.loading()
                val data = makeFlowData() // 실제 데이터 가져오기
                data.collect { result ->
                    _coroutineData.value = CoroutineUiState.success(result)
                }
            } catch (e: Exception) {
                _coroutineData.value = CoroutineUiState.error(e.message.toString()) // 에러 상태
            }
        }

    }

    fun emitSharedFlowData() {
        viewModelScope.launch {
            _sharedFlow.emit("emit ShardFlowData")
        }
    }

    private fun makeFlowData(): Flow<String> = flow {
        delay(1000) // 서버에서 데이터를 가져온다는 시간을 가상으로
        emit("Get Data From Server Successly")
    }
}

 

Fragment 구독

// StateFlow 구독
lifecycleScope.launch {
    repeatOnLifecycle(Lifecycle.State.STARTED) {
        launch {
            coroutineStateFlowViewModel.coroutineData.collect { result ->
                when (result.status) {
                    CoroutineStatus.LOADING -> showLoadingBar()
                    CoroutineStatus.SUCCESS -> setTextView(result.data)
                    CoroutineStatus.ERROR -> showErrorMsg(result.message)
                }
            }
        }

        launch {
            coroutineStateFlowViewModel.sharedFlow.collect { result ->
                setTextView2(result)
            }
        }

        launch {
            coroutineStateFlowViewModel.stateInFlow.collect { result ->
                setTextView3(result)
            }
        }

    }
}