我了解到将 setState(() 和 FutureBuilder 放在一起并不是一个好习惯。当我删除我的 setState(() 时，我注意到isWaiting变量不再更新到MakeCards类并保持为 True。但是当我离开时在我的 setState 中，即使它是空的setState((){ }，isWaiting 也会正确更新为 False。我需要帮助理解为什么会这样，以及如何在删除我的 setState(() 时在MakeCards 中将 isWaiting更新为 False 。
bool isWaiting = true; <------------------------------------------
Future<Map> getData() async {
try {
List<String> coinData = await CoinData();
Map<String, List<String>> graphData = await GraphData()
setState(() { <------------------------------------
coinValues = coinData;
graphValues = graphData;
});
isWaiting = false; <----------------------------------
.
. (some code)
.
return allDataValues;
}
构建方法
MakeCards(
isWaiting: isWaiting, <-----------------------------
selectedCurrency: selectedCurrency,
coinData: allDataValues['lastCoinPrices'])
.makeCards(),
FutureBuilder<Map>(
future: futureData,
builder: (context, snapshot) {
print("FutureBuilder started");
if (!snapshot.hasData)
return CircularProgressIndicator();
else if (snapshot.data.isEmpty)
return Container();
else {
print("FutureBuilder completed");
return Graph(snapshot.data);
}
})
MakeCards（单独的文件）
class MakeCards {
MakeCards({this.isWaiting, this.selectedCurrency, this.coinData});
bool isWaiting;
String selectedCurrency;
List<String> coinData = [];
Row makeCards() {
List<CryptoCard> cryptoCards = [];
for (int i = 0; i < cryptoAbbreviation.length; i++) {
cryptoCards.add(
CryptoCard(
cryptoCurrency: cryptoAbbreviation[i],
selectedCurrency: selectedCurrency,
value: isWaiting ? '---' : coinData[i], <-------------------------
name: cryptoName[i],
// iconContent: iconContent,
),
);
}
return Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: cryptoCards,
);
}
}