Flutter 如何制作;项目:“;等于旋转木马中的可变长度?
我正在制作一个新闻应用程序,在我的Flitter应用程序中使用旋转木马。但问题是,我使用的API有时显示9篇文章,有时显示10篇文章。我想设置一个可以保存apidata.length(9/10)值的变量。但如何将其设置为与CarouselSlider中的项目数相等,即如果api仅发送9篇文章,则显示9张幻灯片;如果是10张,则CarouselSlider应仅显示10张幻灯片Flutter 如何制作;项目:“;等于旋转木马中的可变长度?,flutter,dart,flutter-packages,Flutter,Dart,Flutter Packages,我正在制作一个新闻应用程序,在我的Flitter应用程序中使用旋转木马。但问题是,我使用的API有时显示9篇文章,有时显示10篇文章。我想设置一个可以保存apidata.length(9/10)值的变量。但如何将其设置为与CarouselSlider中的项目数相等,即如果api仅发送9篇文章,则显示9张幻灯片;如果是10张,则CarouselSlider应仅显示10张幻灯片 CarouselSlider( height: 400.0, items: [1,2,3,4,5].map((i)
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(),
)
您可以使用列表来保存数据和控制长度,然后使用map
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 $i', style: TextStyle(fontSize: 16.0),)
);
},
);
}).toList(),
)
List intList=[];
...
@凌驾
void initState(){
增加(1);
增加(2);
...
旋转滑翔机(
高度:400.0,
items:intList.map((i){//如何设置项:[动态值非静态]
返回生成器(
生成器:(BuildContext上下文){
返回容器(
宽度:MediaQuery.of(context).size.width,
边缘:边缘组。对称(水平:5.0),
装饰:盒子装饰(
颜色:颜色。琥珀色
),
子项:文本('Text$i',样式: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 $i', style: TextStyle(fontSize: 16.0),)
);
},
);
}).toList(),
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: Icon(Icons.add),
), // This trailing comma makes auto-formatting nicer for build methods.
);
}
}
导入“包装:颤振/材料.省道”;
导入“package:carousel_slider/carousel_slider.dart”;
void main()=>runApp(MyApp());
类MyApp扩展了无状态小部件{
//此小部件是应用程序的根。
@凌驾
小部件构建(构建上下文){
返回材料PP(
标题:“颤振演示”,
主题:主题数据(
//这是应用程序的主题。
//
//尝试使用“flutter run”运行应用程序。您将看到
//应用程序有一个蓝色工具栏。然后,在不退出应用程序的情况下,重试
//将下面的primarySwatch更改为Colors.green,然后调用
//“热重新加载”(在运行“颤振运行”的控制台中按“r”,
//或者只需将更改保存到颤振IDE中的“热重新加载”。
//请注意,计数器没有重置回零;应用程序
//未重新启动。
主样本:颜色。蓝色,
),
主页:MyHomePage(标题:“颤振演示主页”),
);
}
}
类MyHomePage扩展StatefulWidget{
MyHomePage({Key,this.title}):超级(Key:Key);
//此小部件是应用程序的主页。它是有状态的,表示
//它有一个状态对象(定义如下),其中包含影响
//看起来怎么样。
//此类是状态的配置。它保存值(在此
//案例名称)由家长(在本例中为应用程序小部件)提供,以及
//由State的build方法使用。小部件子类中的字段包括
//始终标记为“最终”。
最后的字符串标题;
@凌驾
_MyHomePageState createState()=>\u MyHomePageState();
}
类_MyHomePageState扩展状态{
int _计数器=0;
List intList=[];
@凌驾
void initState(){
增加(1);
增加(2);
super.initState();
}
void _incrementCounter(){
设置状态(){
//这个对setState的调用告诉颤振框架,某些东西
//已在此状态下更改,这将导致它重新运行下面的生成方法
//以便显示能够反映更新的值。如果我们更改
//_计数器,而不调用setState(),则生成方法将不可用
//再打一次电话,似乎什么也没发生。
_计数器++;
});
}
@凌驾
小部件构建(构建上下文){
//每次调用setState时都会重新运行此方法,例如,按done
//通过上面的_incrementCounter方法。
//
//对颤振框架进行了优化,以制定重新运行的构建方法
//快速,这样你就可以重建任何需要更新的东西
//而不是必须单独更改小部件的实例。
返回脚手架(
appBar:appBar(
//在这里,我们从MyHomePage对象中获取由创建的值
//使用App.build方法,并使用它设置appbar标题。
标题:文本(widget.title),
),
主体:旋转滑翔机(
高度:400.0,
items:intList.map((i){//如何设置项:[动态值非静态]
返回生成器(
生成器:(BuildContext上下文){
返回容器(
宽度:MediaQuery.of(context).size.width,
边缘:边缘组。对称(水平:5.0),
装饰:盒子装饰(
颜色:颜色。琥珀色
),
子项:文本('Text$i',样式:TextStyle(fontSize:16.0),)
);
},
);
}).toList(),
),
浮动操作按钮:浮动操作按钮(
按下时:\ u递增计数器,
工具提示:“增量”,
子:图标(Icons.add),
),//此尾随逗号使生成方法的自动格式设置更方便。
);
}
}
我必须使用intList=List.generate(长度,(int-index)=>index);