導航欄顫動應用程式未在螢屏上顯示任何位置

我正在嘗試在我的移動應用程式中列印導航欄。main.dart 的代碼：系統說未使用包 navbar.dart 的匯入。導航欄完全沒有顯示。有誰知道如何解決這一問題？天氣應用程式本身確實有效。但導航欄不列印。PLaceholderPLaceholderPLaceholderPLaceholderPLaceholderPLaceholderPLaceholderPLaceholderPLaceholderPLaceholderPLaceholderPLaceholderPLaceholder

import 'package:weerappflutter/data_service.dart';
import 'package:flutter/material.dart';
import 'package:weerappflutter/models.dart';
import 'package:weerappflutter/navbar.dart';


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

}

class MyApp extends StatefulWidget {
  @override
  State<StatefulWidget> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  final _cityTextController = TextEditingController();
  final _dataService = DataService();

WeatherResponse? _response;

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        home: Scaffold(
          body: Center(
            child: Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: [
                if (_response != null)
                  Column(
                    children: [
                      Image.network(_response!.iconUrl),
                      Text(
                        '${_response!.tempInfo.temperature}°',
                        style: TextStyle(fontSize: 40),
                      ),
                      Text(_response!.weatherInfo.description)


                    ],
                  ),
                Padding(
                  padding: EdgeInsets.symmetric(vertical: 50),
                  child: SizedBox(
                    width: 150,
                    child: TextField(
                        controller: _cityTextController,
                        decoration: InputDecoration(labelText: 'Voer een stad in:'),
                        textAlign: TextAlign.center),
                  ),
                ),
                ElevatedButton(onPressed: _search, child: Text('Toon temparatuur'))
              ],
            ),
          ),
        ));
  }

  void _search() async {
    final response = await _dataService.getWeather(_cityTextController.text);
    setState(() => _response = response);
  }
}

代碼導航欄.dart

import 'package:flutter/material.dart';

class NavBar extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Drawer(
      child: ListView(
        // Remove padding
        padding: EdgeInsets.zero,
        children: [
          UserAccountsDrawerHeader(
            accountName: Text('WeerBeving'),
            accountEmail: Text('WeerBeving.com'),
            currentAccountPicture: CircleAvatar(
              child: ClipOval(
                child: Image.network(
                  'https://oflutter.com/wp-content/uploads/2021/02/girl-profile.png',
                  fit: BoxFit.cover,
                  width: 90,
                  height: 90,
                ),
              ),
            ),
            decoration: BoxDecoration(
              color: Colors.blue,
              image: DecorationImage(
                  fit: BoxFit.fill,
                  image: NetworkImage(
                      'https://oflutter.com/wp-content/uploads/2021/02/profile-bg3.jpg')),
            ),
          ),
          ListTile(
            leading: Icon(Icons.favorite),
            title: Text('Weer'),
            onTap: () => null,
          ),
          ListTile(
            leading: Icon(Icons.person),
            title: Text('Aardbevingen Nederland'),
            onTap: () => null,
          ),
          ListTile(
            leading: Icon(Icons.share),
            title: Text('Aardbevingen wereldwijd'),
            onTap: () => null,
          ),

          Divider(),
          ListTile(
            title: Text('Exit'),
            leading: Icon(Icons.exit_to_app),
            onTap: () => null,
          ),
        ],
      ),
    );
  }
}

uj5u.com熱心網友回復：

在身體正上方的腳手架內寫

drawer:NavBar(),

你只匯入了包，但沒有在 main.dart 中的任何地方呼叫它

uj5u.com熱心網友回復：

您已宣告 NavBar 小部件，但您忘記將其放置到小部件樹中。為此，請使用 Scaffold ... Scaffold( drawer: NavBar(), body: ... ) 的抽屜欄位

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