Cannot localize strings in Flutter TabBarView

问题

When I try to localize a string in a TabBarView I get this error:

NoSuchMethodError: The method 'translate' was called on null. Receiver: null. Tried calling: translate("username).

I use this line of code to translate a key to a localized string:

AppLocalizations.of(context).translate('username')

This works great in all the other screens of my app except this one. Does anyone know why it's not working and how to solve it?

Some things I already tried:

pass the context of the main screen (the screen that holds all the TabBarViews)
wrap every ListTile in a Builder
wrap the ListView in a Builder

Code:

class AccountScreen extends StatelessWidget {
  final String username;
  final String email;
  final int points;

  AccountScreen(this.username, this.email, this.points);

  @override
  Widget build(BuildContext context) {
    return Container(
      child: Padding(
        padding: EdgeInsets.all(10),
        child: ListView(
          children: <Widget>[
            ListTile(
              title: Text(AppLocalizations.of(context).translate('username')),
              subtitle: Text(username),
            ),
            ListTile(
              title:
                  Text(AppLocalizations.of(context).translate('email_address')),
              subtitle: Text(email),
            ),
            ListTile(
              title: Text(AppLocalizations.of(context).translate('points')),
              subtitle: Text('$points'),
            ),
          ],
        ),
      ),
    );
  }
}

回答1:

I found same problem. But in my case is using MaterialApp without localizationsDelegates. (I mean all file not only main.dart).

So i add localizationsDelegates on every MaterialApp in all widget.

e.g.

   MaterialApp(
      localizationsDelegates: [
        MainLocalizationsDelegate.delegate,
        GlobalMaterialLocalizations.delegate,
        GlobalWidgetsLocalizations.delegate,
        GlobalCupertinoLocalizations.delegate,
      ],
      home: DefaultTabController(
        length: 2,
        child: Scaffold(
          appBar: AppBar(
            brightness: Brightness.light,
            bottom: TabBar(
              tabs: [
                Tab(text: MainLocalizations.of(context).food),
                Tab(text: MainLocalizations.of(context).car),
              ],
            ),
          ),
          body: TabBarView(
            children: [
              TabA(),
              TabB(),
            ],
          ),
        ),
      ),
    );

回答2:

The problem was that there were multiple MaterialApp widgets inside the app that were causing some conflicts regarding the localisation process. Removing the Redundant MaterialApp widgets fixed the issue.

来源：https://stackoverflow.com/questions/57101411/cannot-localize-strings-in-flutter-tabbarview

标签

Flutter

localization