学习就是先抄后改造：
官方demo如下：
import 'package:english_words/english_words.dart';
import 'package:flutter/material.dart';
class RandomWords extends StatefulWidget {
@override
createState() => new RandomWordsState();
}
class RandomWordsState extends State<RandomWords> {
final _suggestions = <WordPair>[];
final _biggerFont = const TextStyle(fontSize: 18.0);
final _saved = new Set<WordPair>();
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('官方Demo'),
actions: <Widget>[
IconButton(icon: Icon(Icons.list), onPressed: _pushSaved),
],
),
body: _buildSuggestions(),
);
}
Widget _buildSuggestions() {
return ListView.builder(
padding: const EdgeInsets.all(16.0),
itemBuilder: (context, i) {
if (i.isOdd) return Divider();
final index = i ~/ 2;
if (index >= _suggestions.length) {
_suggestions.addAll(generateWordPairs().take(10));
}
return _buildRow(_suggestions[index]);
}
);
}
Widget _buildRow(WordPair pair) {
final alreadySaved = _saved.contains(pair);
return ListTile(
title: Text(
pair.asPascalCase,
style: _biggerFont,
),
trailing: Icon(
alreadySaved ? Icons.favorite : Icons.favorite_border,
color: alreadySaved ? Colors.red : null,
),
onTap: () {
setState(() {
if (alreadySaved) {
_saved.remove(pair);
} else {
_saved.add(pair);
}
});
},
);
}
//
// void _pushSaved() {
// print('ererewr===$_saved',);
// Navigator.of(context).pushNamed("SaveRandomWords", arguments: _saved);
// }
// }
void _pushSaved() {
Navigator.of(context).push(
new MaterialPageRoute(
//其实官方Demo这里时第二个页面的内容和渲染
// 都放在了路由的方法里面做，所以萌生了抽离放到单独页面的文件中，这里只管跳转例如上面被注释的代码
builder: (context) {
final tiles = _saved.map(
(pair) {
return new ListTile(
title: new Text(
pair.asPascalCase,
style: _biggerFont,
),
);
},
);
final divided = ListTile
.divideTiles(
context: context,
tiles: tiles,
)
.toList();
return new Scaffold(
appBar: new AppBar(
title: new Text('Saved Suggestions'),
),
body: new ListView(children: divided),
);
},
),
);
}
}
一个文件代码太多，抽取一下，改造后：
// RandomWordsState.dart
import 'package:english_words/english_words.dart';
import 'package:flutter/material.dart';
class RandomWords extends StatefulWidget {
@override
createState() => new RandomWordsState();
}
class RandomWordsState extends State<RandomWords> {
final _suggestions = <WordPair>[];
final _biggerFont = const TextStyle(fontSize: 18.0);
final _saved = new Set<WordPair>();
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('官方Demo'),
actions: <Widget>[
IconButton(icon: Icon(Icons.list), onPressed: _pushSaved),
],
),
body: _buildSuggestions(),
);
}
Widget _buildSuggestions() {
return ListView.builder(
padding: const EdgeInsets.all(16.0),
itemBuilder: (context, i) {
if (i.isOdd) return Divider();
final index = i ~/ 2;
if (index >= _suggestions.length) {
_suggestions.addAll(generateWordPairs().take(10));
}
return _buildRow(_suggestions[index]);
}
);
}
Widget _buildRow(WordPair pair) {
final alreadySaved = _saved.contains(pair);
return ListTile(
title: Text(
pair.asPascalCase,
style: _biggerFont,
),
trailing: Icon(
alreadySaved ? Icons.favorite : Icons.favorite_border,
color: alreadySaved ? Colors.red : null,
),
onTap: () {
setState(() {
if (alreadySaved) {
_saved.remove(pair);
} else {
_saved.add(pair);
}
});
},
);
}
void _pushSaved() {
Navigator.of(context).pushNamed("SaveRandomWords", arguments: _saved);
}
}
// SaveRandomWords.dart
import 'package:flutter/material.dart';
class SaveRandomWords extends StatelessWidget{
SaveRandomWords({
Key key,
@required this.text, // 接收一个text参数
}) : super(key: key);
final text;
final _biggerFont = const TextStyle(fontSize: 18.0);
@override
Widget build(BuildContext context) {
final tiles = text.map((pair){
return new ListTile(
title: Text(
pair.asPascalCase,
style: _biggerFont,
),
);
});
final divided = ListTile.divideTiles(context: context, tiles: tiles).toList();
return new Scaffold(
appBar: AppBar(
title: Text("Saved Suggestions"),
),
body: new ListView(children: divided),
);
}
}
// MyApp.dart
import 'package:flutter/material.dart';
import 'pageWidget/MyHomePage.dart';
import 'pageWidget/NewRoute.dart';
import 'pageWidget/SaveRandomWords.dart';
import 'pageWidget/TipRoute.dart';
import 'pageWidget/RandomWords.dart';
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue
),
// initialRoute: "NewRoute",
// routes: {
// "NewRoute": (context) => NewRoute(),
// // "/": (context)=>MyHomePage(title: 'Flutter'),
// "TipRoute": (context){return TipRoute(text: ModalRoute.of(context).settings.arguments);}
// },
home: MyHomePage(title: 'Flutter'),
onGenerateRoute: (settings) {
var name = settings.name;
var args = settings.arguments;
// Do something here
switch (name) {
case '/':
return MaterialPageRoute(builder: (context) => MyHomePage(title: '菜鸟的进阶'));
case 'TipRoute':
return MaterialPageRoute(builder: (context) => TipRoute(text: args),maintainState: false,fullscreenDialog: true);
case 'NewRoute':
return MaterialPageRoute(builder: (context) => NewRoute());
case 'RandomWords':
return MaterialPageRoute(builder: (context)=> RandomWords());
case 'SaveRandomWords':
return MaterialPageRoute(builder: (context)=> SaveRandomWords(text: args));
default:
return MaterialPageRoute(builder: (context) => NewRoute());
}
},
);
}
}
/*
MaterialPageRoute:构造函数的各个参数的意义
MaterialPageRoute({
WidgetBuilder builder,
RouteSettings settings,
bool maintainState = true,
bool fullscreenDialog = false,
})
builder：是一个WidgetBuilder类型的回调函数，它的作用是构建路由页的具体 内容，返回值是一个widget.我们通常要实现此回调，返回新的路由实例
settings：包含路由的配置信息，如路由名称，是否初始路由（首页）
maintainSate：默认情况下，当入栈一个新路由时，原来的路由仍然会保存在内存中，如果想在路由没用的时候释放其所占的资源，可以其为false
fullscreenDialog：表示新的路由页面是否是一个全屏的模态对话框，在IOS中，如果fullscreenDialog为true,新页面将会从屏幕底部滑入（而不是水平方向）
===================================================================================================
Navigator:路由管理组件
push：将给定的路由入栈，返回值是一个future对象，用以接收新路由出栈（即关闭）时的返回数据。
pop: 将栈顶路由出栈，result为页面关闭时返回给上一个页面的数据。
Navigator.push(BuildContext context,Route route) 等价于 Navigator.of(context).push(Route route);
*/
妈咦，咋还出错了，结果运行提示：type 'EfficientLengthMappedIterable<WordPair, dynamic>' is not a subtype of type 'Iterable<Widget>'
纳闷，这不是只是抽取了一下代码到另外一个文件而已吗？
我们分析提示，这里大致的意识时类型不对，那根据提示我们在对于的数据map之后添加对于的类型
问题代如下：
final tiles = text.map((pair){
return new ListTile(
title: Text(
pair.asPascalCase,
style: _biggerFont,
),
);
});
改造后：
final tiles = text.map<Widget>((pair){
return new ListTile(
title: Text(
pair.asPascalCase,
style: _biggerFont,
),
);
});
编译成功顺利运行！！！
