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我收到此错误“类型“未来”不是“应用程序元”类型的子类型。我创建了一个支付功能。支付功能类型为future<List>。此函数返回列表中的 installedUpiapps。我需要将参数传递给 appWidget。但我得到这个错误'类型'Future'不是'ApplicationMeta'类型的子类型。

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);
 }
}
4

1 回答 1

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将返回类型添加到payment方法后，您应该会看到编译错误。

payment是async，所以它返回一个Future。为了用它构建一个小部件，你必须使用FutureBuilder这里描述的https://api.flutter.dev/flutter/widgets/FutureBuilder-class.html

FutureBuilder<List<ApplicationMeta>>(
  future: as
  builder: (context, snapshot) {
    // your widgets go here
  }
)

至于显示列表ApplicationMeta，请查看以下内容：

于 2021-06-13T12:44:12.787 回答