Почему мой степпер продолжает выдавать нулевой результат? флаттер - PullRequest
0 голосов
/ 07 ноября 2019

Я пытаюсь научиться использовать шаговый виджет, но столкнулся с проблемой. В настоящее время на моем шаге 3 предполагается отображение всего пользовательского ввода с шагов 1 и 2. Вывод для обоих значений равен нулю. Почему это так?

Это мой код:

import 'package:flutter/services.dart';

class StoreManagement extends StatefulWidget {
static const String pageId = 'StoreManagement';
@override
_StoreManagementState createState() => _StoreManagementState();
}

class _StoreManagementState extends State<StoreManagement> {
List<Step> _steps;
int _current;
TextEditingController _name;
TextEditingController _age;
String _nameDisplay;
String _ageDisplay;

void _stepContinue() {
 setState(() {
   _current++;
   if (_current >= _steps.length) _current = _steps.length - 1;
   if (_current == 2) {
     _ageDisplay = _age.text;
     _nameDisplay = _name.text;
   }
 });
}

void _stepCancel() {
 setState(() {
   _current--;
   if (_current < 0) _current = 0;
 });
}

void _stepTap(int index) {
 setState(() {
   _current = index;
 });
}

@override
void initState() {
 _name = TextEditingController();
 _age = TextEditingController();
 _current = 0;
 _steps = <Step>[
   Step(
     isActive: true,
     title: Text('Enter your name'),
     content: TextField(
       controller: _name,
       decoration: InputDecoration(labelText: 'Enter your Name'),
     ),
   ),
   Step(
     isActive: true,
     title: Text('Enter your age'),
     content: TextField(
       keyboardType: TextInputType.number,
       controller: _age,
       decoration: InputDecoration(
         labelText: 'Enter your Age',
       ),
     ),
   ),
   Step(
     isActive: true,
     title: Text('Step 3'),
     content: Column(
       children: <Widget>[
         Text('You have entered: '),
         Text('Your name is : ${_nameDisplay}'),
         Text('Your age is : ${_ageDisplay}'),
       ],
     ),
   )
 ];
 super.initState();
}

@override
Widget build(BuildContext context) {
 return Scaffold(
   body: Stepper(
     steps: _steps,
     currentStep: _current,
     type: StepperType.vertical,
     onStepCancel: _stepCancel,
     onStepContinue: _stepContinue,
     onStepTapped: _stepTap,
   ),
 );
}
}

Я пытался напечатать значение за пределами шагового устройства, но, похоже, оно работает. Не совсем понимаю, почему это не работает на третьем этапе.

1 Ответ

1 голос
/ 07 ноября 2019

Вы можете вернуть шаг с помощью функции
Вы можете скопировать полный код вставки и запуска ниже
фрагмент кода

Widget build(BuildContext context) {
    return Scaffold(
      body: Stepper(
        steps: buildStep(),

...

List<Step> buildStep() {
_steps = <Step>[
  Step(
    isActive: true,
    title: Text('Enter your name'),
    content: TextField(
      controller: _name,
      decoration: InputDecoration(labelText: 'Enter your Name'),
    ),
  ),
  Step(
    isActive: true,
    title: Text('Enter your age'),
    content: TextField(
      keyboardType: TextInputType.number,
      controller: _age,
      decoration: InputDecoration(
        labelText: 'Enter your Age',
      ),
    ),
  ),
  Step(
    isActive: true,
    title: Text('Step 3'),
    content: Column(
      children: <Widget>[
        Text('You have entered: '),
        Text('Your name is : ${_nameDisplay}'),
        Text('Your age is : ${_ageDisplay}'),
      ],
    ),
  )
];

return _steps;
}

рабочая демонстрация

enter image description here

полный код

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',
      theme: ThemeData(
        // This is the theme of your application.
        //
        // Try running your application with "flutter run". You'll see the
        // application has a blue toolbar. Then, without quitting the app, try
        // changing the primarySwatch below to Colors.green and then invoke
        // "hot reload" (press "r" in the console where you ran "flutter run",
        // or simply save your changes to "hot reload" in a Flutter IDE).
        // Notice that the counter didn't reset back to zero; the application
        // is not restarted.
        primarySwatch: Colors.blue,
      ),
      home: StoreManagement(),
    );
  }
}

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

  // This widget is the home page of your application. It is stateful, meaning
  // that it has a State object (defined below) that contains fields that affect
  // how it looks.

  // This class is the configuration for the state. It holds the values (in this
  // case the title) provided by the parent (in this case the App widget) and
  // used by the build method of the State. Fields in a Widget subclass are
  // always marked "final".

  final String title;

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

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  void _incrementCounter() {
    setState(() {
      // This call to setState tells the Flutter framework that something has
      // changed in this State, which causes it to rerun the build method below
      // so that the display can reflect the updated values. If we changed
      // _counter without calling setState(), then the build method would not be
      // called again, and so nothing would appear to happen.
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    // This method is rerun every time setState is called, for instance as done
    // by the _incrementCounter method above.
    //
    // The Flutter framework has been optimized to make rerunning build methods
    // fast, so that you can just rebuild anything that needs updating rather
    // than having to individually change instances of widgets.
    return Scaffold(
      appBar: AppBar(
        // Here we take the value from the MyHomePage object that was created by
        // the App.build method, and use it to set our appbar title.
        title: Text(widget.title),
      ),
      body: Center(
        // Center is a layout widget. It takes a single child and positions it
        // in the middle of the parent.
        child: Column(
          // Column is also a layout widget. It takes a list of children and
          // arranges them vertically. By default, it sizes itself to fit its
          // children horizontally, and tries to be as tall as its parent.
          //
          // Invoke "debug painting" (press "p" in the console, choose the
          // "Toggle Debug Paint" action from the Flutter Inspector in Android
          // Studio, or the "Toggle Debug Paint" command in Visual Studio Code)
          // to see the wireframe for each widget.
          //
          // Column has various properties to control how it sizes itself and
          // how it positions its children. Here we use mainAxisAlignment to
          // center the children vertically; the main axis here is the vertical
          // axis because Columns are vertical (the cross axis would be
          // horizontal).
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.display1,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}


class StoreManagement extends StatefulWidget {
  static const String pageId = 'StoreManagement';
  @override
  _StoreManagementState createState() => _StoreManagementState();
}

class _StoreManagementState extends State<StoreManagement> {
  List<Step> _steps;
  int _current;
  TextEditingController _name;
  TextEditingController _age;
  String _nameDisplay;
  String _ageDisplay;

  void _stepContinue() {
    setState(() {
      _current++;
      if (_current >= _steps.length) _current = _steps.length - 1;
      print('current ${_current}');
      if (_current == 2) {
        _ageDisplay = _age.text;
        print('_ageDisplay ${_ageDisplay}');
        _nameDisplay = _name.text;
        print('_nameDisplay ${_nameDisplay}');
      }
    });
  }

  void _stepCancel() {
    setState(() {
      _current--;
      if (_current < 0) _current = 0;
    });
  }

  void _stepTap(int index) {
    setState(() {
      _current = index;
    });
  }

  @override
  void initState() {
    _name = TextEditingController();
    _age = TextEditingController();
    _current = 0;

    super.initState();
  }

  List<Step> buildStep() {
    _steps = <Step>[
      Step(
        isActive: true,
        title: Text('Enter your name'),
        content: TextField(
          controller: _name,
          decoration: InputDecoration(labelText: 'Enter your Name'),
        ),
      ),
      Step(
        isActive: true,
        title: Text('Enter your age'),
        content: TextField(
          keyboardType: TextInputType.number,
          controller: _age,
          decoration: InputDecoration(
            labelText: 'Enter your Age',
          ),
        ),
      ),
      Step(
        isActive: true,
        title: Text('Step 3'),
        content: Column(
          children: <Widget>[
            Text('You have entered: '),
            Text('Your name is : ${_nameDisplay}'),
            Text('Your age is : ${_ageDisplay}'),
          ],
        ),
      )
    ];

    return _steps;
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Stepper(
        steps: buildStep(),
        currentStep: _current,
        type: StepperType.vertical,
        onStepCancel: _stepCancel,
        onStepContinue: _stepContinue,
        onStepTapped: _stepTap,
      ),
    );
  }
}
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