Question

当我构建一个flutter应用程序时，有三个屏幕，屏幕A，屏幕B，屏幕C。单击按钮时，它将重定向到下一个屏幕。因此它将重定向A到B。但是不重定向B到C。我不知道原因。显示错误。它显示错误是

Could not find a generator for route RouteSettings("/extractArguments1", Instance of 'ScreenArguments') in the _WidgetsAppState.

我的代码显示如下

    import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      routes: {
        '/extractArguments': (context) => ExtractArgumentsScreen(),
        '/extractArguments1': (context) => ExtractArgumentsScreen1(),
      },
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {




  @override
  Widget build(BuildContext context) {

    return Scaffold(
      appBar: AppBar(

        title: Text("A"),
      ),
      body: Center(
        child: new RaisedButton(onPressed: (){
          Navigator.pushNamed(context, "/extractArguments",arguments: ScreenArguments("title", "message"));
        },
        child: new Text("Click"),),

      ),

    );
  }
}


class ScreenArguments {
  final String title;
  final String message;

  ScreenArguments(this.title, this.message);
}

class ExtractArgumentsScreen extends StatelessWidget{

ExtractArgumentsScreen({
    Key key,
    @required this.title,
    @required this.message,
  }): super(key: key);

  final String title;
  final String message;

  @override
  Widget build(BuildContext context) {

    final ScreenArguments args = ModalRoute.of(context).settings.arguments;


    // return new Scaffold(
    //   appBar: new AppBar(title: new Text('args.title')),
    //     body: new Center(child: new Text('args.message'),),
    // );

    return MaterialApp(
      title: 'Flutter Demo',

      home: MyHomePage1(title: 'Flutter Demo Home Page'),
    );


  }



}


class MyHomePage1 extends StatefulWidget {
  MyHomePage1({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePage1State createState() => _MyHomePage1State();
}

class _MyHomePage1State extends State<MyHomePage1> {




  @override
  Widget build(BuildContext context) {

    return Scaffold(
      appBar: AppBar(

        title: Text("B"),
      ),
      body: Center(
        child: new RaisedButton(onPressed: (){
          Navigator.pushNamed(context, "/extractArguments1",arguments: ScreenArguments("title", "message"));
        },
        child: new Text("Click"),),

      ),

    );
  }
}

class ExtractArgumentsScreen1 extends StatelessWidget{

ExtractArgumentsScreen1({
    Key key,
    @required this.title,
    @required this.message,
  }): super(key: key);

  final String title;
  final String message;

  @override
  Widget build(BuildContext context) {

    final ScreenArguments args = ModalRoute.of(context).settings.arguments;


    // return new Scaffold(
    //   appBar: new AppBar(title: new Text('args.title')),
    //     body: new Center(child: new Text('args.message'),),
    // );

    return MaterialApp(
      title: 'Flutter Demo',

      home: MyHomePage2(title: 'Flutter Demo Home Page'),
    );


  }



}


class MyHomePage2 extends StatefulWidget {
  MyHomePage2({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePage2State createState() => _MyHomePage2State();
}

class _MyHomePage2State extends State<MyHomePage2> {




  @override
  Widget build(BuildContext context) {

    return Scaffold(
      appBar: AppBar(

        title: Text("C"),
      ),
      body: Center(
        child: new RaisedButton(onPressed: (){
      //   Navigator.pushNamed(context, "/extractArguments1",arguments: ScreenArguments("title", "message"));
        },
        child: new Text("Click"),),

      ),

    );
  }
}

完全错误是

     The following assertion was thrown while handling a gesture:
  I/flutter (23854): Could not find a generator for route RouteSettings("/extractArguments1", Instance of
  I/flutter (23854): 'ScreenArguments') in the _WidgetsAppState.
  I/flutter (23854): Generators for routes are searched for in the following order:
  I/flutter (23854):  1. For the "/" route, the "home" property, if non-null, is used.
  I/flutter (23854):  2. Otherwise, the "routes" table is used, if it has an entry for the route.
  I/flutter (23854):  3. Otherwise, onGenerateRoute is called. It should return a non-null value for any valid route not
  I/flutter (23854): handled by "home" and "routes".
  I/flutter (23854):  4. Finally if all else fails onUnknownRoute is called.
  I/flutter (23854): Unfortunately, onUnknownRoute was not set.

请帮助我找到问题。

Answer 1

问题是当您打电话时：

<encoder class="net.logstash.logback.encoder.LoggingEventCompositeJsonEncoder">
   <providers>
      <timestamp>%d{ISO8601}</timestamp>
      <message/>
      <loggerName/>
      <context/>
      <mdc/>
      <pattern>
         <pattern>
            {
            "appVersion": "${build.version}",
            "appName": "${build.artifact}",
            "resourceType": "${logback.application.resource.type}",
            "resourceID": "${logback.application.resource.id}",
            "level": "%level",
            "hostname": "${logback.server.host}",
            "indexType": "${logback.logstash.index.type}"
            }
         </pattern>
         </layout>
      </pattern>
      <stackTrace/>
   </providers>
</encoder>

您正在命名路由中传递参数，但是您无处接受参数。您需要在onGenerateRoute()函数中提取参数，并将其传递给小部件。 onGenerateRoute（）函数根据给定的RouteSettings创建正确的路由。因此，您可以做的是在材料应用程序内部添加onGenerateRoute（）函数，如下所示：

 Navigator.pushNamed(context, "/extractArguments1",arguments: ScreenArguments("title", "message"));

此函数将处理参数正确地将它们传递到相应的屏幕屏幕。有关参考，请参见official documentation。

扑扑的路线，显示找不到路由RouteSettings的生成器

1 个答案: