flutter - 如何使“项目:”等于 CarouselSlider 中的可变长度?
问题描述
我正在制作一个新闻应用程序,并且在我的颤振应用程序中使用 CarouselSlider。但问题是,我使用的 API 有时会显示 9 篇文章,有时会显示 10 篇文章。我想设置一个可以保存 apidata.length(9/10) 值的变量。但是如何将它设置为等于 CarouselSlider 中的项目数,即如果 api 仅发送 9 篇文章则显示 9 张幻灯片,或者如果 10 则 CarouselSlider 应该只显示 10 张幻灯片。
CarouselSlider(
height: 400.0,
items: [1,2,3,4,5].map((i) { //How to set the items: [dynamic value not static]
return Builder(
builder: (BuildContext context) {
return Container(
width: MediaQuery.of(context).size.width,
margin: EdgeInsets.symmetric(horizontal: 5.0),
decoration: BoxDecoration(
color: Colors.amber
),
child: Text('text $i', style: TextStyle(fontSize: 16.0),)
);
},
);
}).toList(),
)
解决方案
您可以使用列表来保存数据和控制长度,然后使用地图
代码片段
List<int> intList = [];
...
@override
void initState() {
intList.add(1);
intList.add(2);
...
CarouselSlider(
height: 400.0,
items: intList.map((i) { //How to set the items: [dynamic value not static]
return Builder(
builder: (BuildContext context) {
return Container(
width: MediaQuery.of(context).size.width,
margin: EdgeInsets.symmetric(horizontal: 5.0),
decoration: BoxDecoration(
color: Colors.amber
),
child: Text('text $i', style: TextStyle(fontSize: 16.0),)
);
},
);
}).toList(),
)
完整代码
import 'package:flutter/material.dart';
import 'package:carousel_slider/carousel_slider.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: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
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;
List<int> intList = [];
@override
void initState() {
intList.add(1);
intList.add(2);
super.initState();
}
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: CarouselSlider(
height: 400.0,
items: intList.map((i) { //How to set the items: [dynamic value not static]
return Builder(
builder: (BuildContext context) {
return Container(
width: MediaQuery.of(context).size.width,
margin: EdgeInsets.symmetric(horizontal: 5.0),
decoration: BoxDecoration(
color: Colors.amber
),
child: Text('text $i', style: TextStyle(fontSize: 16.0),)
);
},
);
}).toList(),
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: Icon(Icons.add),
), // This trailing comma makes auto-formatting nicer for build methods.
);
}
}
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