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How to importing library that define "favorites" at Flutter(如何导入在颤动中定义“收藏夹”的库)

转载 作者:bug小助手 更新时间:2023-10-25 18:51:40 26 4
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i am very beginner ..and just start learning flutter. I follow "Your First Flutter App" from Google Codelabs, and stop at this step: https://codelabs.developers.google.com/codelabs/flutter-codelab-first?hl=en#6

我还是个初学者,才刚刚开始学扑翼。我关注的是谷歌Codelabs上的“你的第一款颤动应用”,并止步于这一步:https://codelabs.developers.google.com/codelabs/flutter-codelab-first?hl=en#6


the instruction want to divide 2 column and user can see the favorites name they've choosen at favorites pages.
i copied the code to my main.dart (i use Visual Studio Code),after save the file, i dont see any changes at the view...i re-debug the application, and the visual studio code say:

该说明想要分成两栏,用户可以在收藏夹页面上看到他们选择的收藏夹名称。我将代码复制到我的Main.Dart(我使用的是Visual Studio代码),保存文件后,我在视图中看不到任何更改...我重新调试应用程序,而Visual Studio代码显示:


build error exist in your project.

您的项目中存在生成错误。


the problem is:
The getter 'favorites' isn't defined for the type 'MyAppState'.
Try importing the library that defines 'favorites', correcting the name to the name of an existing getter, or defining a getter or field named 'favorites'.

问题是:没有为类型‘MyAppState’定义getter‘Favorites’。尝试导入定义“Favorites”的库,将名称更正为现有getter的名称,或定义名为“Favorites”的getter或字段。


could any one help me for this case...thank you so much

有人能帮我处理这个案子吗……非常感谢


i try copy the codes from https://codelabs.developers.google.com/codelabs/flutter-codelab-first?hl=en#6

我试着从https://codelabs.developers.google.com/codelabs/flutter-codelab-first?hl=en#6复制代码


all of my main.dart after i copied is below:

我复制后的所有Main.Dart如下:


import 'package:english_words/english_words.dart';
import 'package:flutter/material.dart';
import 'package:provider/provider.dart';

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

class MyApp extends StatelessWidget {
const MyApp({super.key});

@override
Widget build(BuildContext context) {
return ChangeNotifierProvider(
create: (context) => MyAppState(),
child: MaterialApp(
title: 'my_awesome_namer',
theme: ThemeData(
useMaterial3: true,
colorScheme: ColorScheme.fromSeed(seedColor: Color.fromRGBO(90, 124, 181, 1)),
),
home: MyHomePage(),
),
);
}
}

class MyAppState extends ChangeNotifier {
var current = WordPair.random();

// ↓ Add this.
void getNext() {
current = WordPair.random();
notifyListeners();
}

void toggleFavorite() {}
}

// ...

// ...

class MyHomePage extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Scaffold(
body: Row(
children: [
SafeArea(
child: NavigationRail(
extended: false,
destinations: [
NavigationRailDestination(
icon: Icon(Icons.home),
label: Text('Home'),
),
NavigationRailDestination(
icon: Icon(Icons.favorite),
label: Text('Favorites'),
),
],
selectedIndex: 0,
onDestinationSelected: (value) {
print('selected: $value');
},
),
),
Expanded(
child: Container(
color: Theme.of(context).colorScheme.primaryContainer,
child: GeneratorPage(),
),
),
],
),
);
}
}


class GeneratorPage extends StatelessWidget {
@override
Widget build(BuildContext context) {
var appState = context.watch<MyAppState>();
var pair = appState.current;

IconData icon;
if (appState.favorites.contains(pair)) {
icon = Icons.favorite;
} else {
icon = Icons.favorite_border;
}

return Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
BigCard(pair: pair),
SizedBox(height: 10),
Row(
mainAxisSize: MainAxisSize.min,
children: [
ElevatedButton.icon(
onPressed: () {
appState.toggleFavorite();
},
icon: Icon(icon),
label: Text('Like'),
),
SizedBox(width: 10),
ElevatedButton(
onPressed: () {
appState.getNext();
},
child: Text('Next'),
),
],
),
],
),
);
}
}

// ...

class BigCard extends StatelessWidget {
const BigCard({
super.key,
required this.pair,
});

final WordPair pair;


@override
Widget build(BuildContext context) {
final theme = Theme.of(context); // ← Add this.
// ↓ Add this.
final style = theme.textTheme.displayMedium!.copyWith(
color: theme.colorScheme.onPrimary,
);

return Card(
color: theme.colorScheme.primary, // ← And also this.
child: Padding(
padding: const EdgeInsets.all(20),
// ↓ Change this line.
// ↓ Make the following change.
child: Text(
pair.asLowerCase,
style: style,
semanticsLabel: "${pair.first} ${pair.second}",
),
),
);
}
}
// ...

i expect:
homepage divide to 2 column and user can see the favorites name they haven choosen at favorites pages (will add extra code from google code labs later)

我期望:主页分为2栏,用户可以在收藏夹页面上看到他们选择的收藏夹名称(稍后将添加来自谷歌代码实验室的额外代码)


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优秀答案推荐

You need to create a list named favorites on MyAppState. It will be

您需要在MyAppState上创建一个名为Favorites的列表。会是


class MyAppState extends ChangeNotifier {
var current = WordPair.random();

// ↓ Add this.
void getNext() {
current = WordPair.random();
notifyListeners();
}

var favorites = <WordPair>[]; //this line

void toggleFavorite() {}
}

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