Flutter为AppLocalization返回空值,of(上下文)

nnt7mjpx 于 2023-03-13 发布在 Flutter

关注(0)|答案(4)|浏览(177)

我正在使用Flutter构建一个Web应用程序，我想在我的新应用程序上使用flutter的国际化特性。我正在使用Flutter-Tutorial，并尝试使用arb-file设置app-title。正如教程中提到的，为“en”和“de”正确创建了app_localization. dart文件。然而，我在以下代码中遇到了一个空指针异常。

import 'package:flutter/material.dart';
import 'package:flutter_localizations/flutter_localizations.dart';
import 'package:flutter_gen/gen_l10n/app_localizations.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'MyApp',
      localizationsDelegates: [
        AppLocalizations.delegate, // Post-EDIT due to croxx5f
        GlobalMaterialLocalizations.delegate,
        GlobalWidgetsLocalizations.delegate,
        GlobalCupertinoLocalizations.delegate,
      ],
      supportedLocales: [
        Locale('de', ''),
        Locale('en', ''),
      ],
      theme: ThemeData(
        primarySwatch: Colors.red,
      ),
      home: Scaffold(
        appBar: AppBar(
          title: Text(AppLocalizations.of(context)!.appTitle),
        ),
        body: Text(AppLocalizations.of(context)!.appTitle)
      ),
    );
  }
}

实际上，AppLocalizations.of（上下文）返回空值。

flutter

来源：https://stackoverflow.com/questions/68884259/flutter-returns-null-for-applocalization-ofcontext

4条答案

按热度按时间

wxclj1h51#

您应该在MaterialApp中添加AppLocalizations：

MaterialApp(
...
      localizationsDelegates: const [
        AppLocalizations.delegate,
        GlobalMaterialLocalizations.delegate,
      ],
      supportedLocales: AppLocalizations.supportedLocales,
...

赞(0）回复(0）举报 2023-03-13

vxqlmq5t2#

在我的案例中，出于测试目的，将Scaffold()用作MaterialApp()的home:导致了该问题。
一旦我创建了一个单独的HomePage()小部件并将其用作home: HomePage()，问题就没有了。

当我将Scaffold（）作为MaterialApp的直接子对象时，会认为AppLocalizationDelegate没有可用的父上下文，因为MaterialApp是所有底层小部件的主要上下文构建器。*

错误代码：

return MaterialApp(
                home: Scaffold(
                  body: Txt(text: AppLocalizations.of(context)?.helloWorld)
                ),
                locale: Locale('ar'),
                supportedLocales: [Locale('en'),Locale('ar')],
                localizationsDelegates: [
                  AppLocalizations.delegate,
                  GlobalMaterialLocalizations.delegate,
                  GlobalCupertinoLocalizations.delegate,
                  GlobalWidgetsLocalizations.delegate,
                ]);
          },
        ));

良好代码：

return MaterialApp(
                home: HomePag(),
                locale: Locale('ar'),
                supportedLocales: [Locale('en'),Locale('ar')],
                localizationsDelegates: [
                  AppLocalizations.delegate,
                  GlobalMaterialLocalizations.delegate,
                  GlobalCupertinoLocalizations.delegate,
                  GlobalWidgetsLocalizations.delegate,
                ]);
          },
        ));


class HomePag extends StatefulWidget {
  const HomePag({Key? key}) : super(key: key);

  @override
  State<HomePag> createState() => _HomePagState();
}

class _HomePagState extends State<HomePag> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Column(
          children: [
            Txt(text: AppLocalizations.of(context)?.helloWorld),
            // Txt(text: AppLocalizations.of(context)?.translate('help'))
          ],
        ),
      ),
    );
  }
}

赞(0）回复(0）举报 2023-03-13

gfttwv5a3#

这对我很有帮助。我有一个Cupertino应用程序在MaterielApp之上，这覆盖了MaterielApp和我的应用程序本地化。（内容）为空
https://github.com/flutter/flutter/issues/26365#issuecomment-523536339

赞(0）回复(0）举报 2023-03-13

jvlzgdj94#

添加l10n.yaml：