问题描述
我收到此错误“类型‘未来’不是‘ApplicationMeta’类型的子类型。 我创建了一个支付功能。支付函数类型为 future
import 'package:Flutter/material.dart';
import 'package:upi_pay/upi_pay.dart';
class Homes extends StatelessWidget {
payment() async {
var appMetaList = await UpiPay.getInstalledUpiApplications();
return appMetaList;
}
Widget appWidget(ApplicationMeta appMeta) {
return Column(
mainAxisAlignment: MainAxisAlignment.center,children: <Widget>[
appMeta.iconImage(48),// logo
Container(
margin: EdgeInsets.only(top: 4),alignment: Alignment.center,child: Text(
appMeta.upiApplication.getAppName(),textAlign: TextAlign.center,),],);
}
@override
Widget build(BuildContext context) {
ApplicationMeta as = payment();
return appWidget(as);
}
}
解决方法
向 payment
方法添加返回类型后,您应该会看到编译错误。
payment
是 async
,所以它返回一个 Future
。为了使用它构建小部件,您必须使用 FutureBuilder
此处所述https://api.flutter.dev/flutter/widgets/FutureBuilder-class.html
FutureBuilder<List<ApplicationMeta>>(
future: as
builder: (context,snapshot) {
// your widgets go here
}
)
至于显示 ApplicationMeta
的列表,请查看以下内容: