Flutter 为 AppLocalization.of(context) 返回 null

Question

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 的国际化功能。我正在关注Flutter-Tutorial，并尝试使用 arb 文件设置应用程序标题。正如教程中提到的，app_localization.dart 文件是为 'en' 和 'de' 正确创建的。然而，我在下面的代码中得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)
      ),
    );
  }
}

其实AppLocalizations.of(context)返回null。

Answer 1

您应该在您的 MaterialApp 中添加AppLocalizations：

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