Flutter 颤振:如何在ListView.builder中显示ListView.builder中的数组数据?
我有这样一个JSON文件:Flutter 颤振:如何在ListView.builder中显示ListView.builder中的数组数据?,flutter,dart,Flutter,Dart,我有这样一个JSON文件: [ { "id": 1, "continent": "North America", "country": [ { "name": "United States", "capital": "Washington, D.C.", "language": [ "English" ] }, { "name": "
[
{
"id": 1,
"continent": "North America",
"country": [
{
"name": "United States",
"capital": "Washington, D.C.",
"language": [
"English"
]
},
{
"name": "Canada",
"capital": "Ottawa",
"language": [
"English",
"French"
]
}
]
},
{
"id": 2,
"continent": "Europe",
"country": [
{
"name": "Germany",
"capital": "Berlin",
"language": [
"German"
]
}
]
}
]
我曾经解析JSON数据。
我创建了一个ListView.builder
来显示大陆的名称现在我想显示每个大陆的“国家名称”、“首都”和“语言”。
所以请帮我做这个,这是主文件
import 'package:flutter/material.dart';
import 'model/continent_model.dart';
import 'services/continent_services.dart';
class ContinentPage extends StatefulWidget {
ContinentPage() : super();
@override
_ContinentPageState createState() => _ContinentPageState();
}
class _ContinentPageState extends State<ContinentPage> {
List<Continent> _continent;
List<Country> _country;
@override
void initState() {
super.initState();
ContinentServices.getContinent().then((continents) {
setState(() {
_continent = continents;
});
});
}
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(),
body: Container(
child: ListView.builder(
itemCount: null == _continent ? 0 : _continent.length,
itemBuilder: (context, index) {
return Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: <Widget>[
Text(_continent[index].continent),
// how to create a ListView show a Column that includes:
// _country[index].name,
// _country[index].capital,
// _country[index].language,
],
);
})));
}
}
导入“包装:颤振/材料.省道”;
导入“model/contraction_model.dart”;
导入“服务/大陆服务.dart”;
类页扩展StatefulWidget{
第页():超级();
@凌驾
_ContinentPageState createState()=>\u ContinentPageState();
}
类PageState扩展了状态{
欧洲大陆名单;
国家名单;
@凌驾
void initState(){
super.initState();
ContinentServices.getContinental().then((大陆){
设置状态(){
_大陆=大陆;
});
});
}
小部件构建(构建上下文){
返回脚手架(
appBar:appBar(),
主体:容器(
子项:ListView.builder(
itemCount:null==\u大陆?0:\u大陆.length,
itemBuilder:(上下文,索引){
返回行(
mainAxisAlignment:mainAxisAlignment.spaceBetween,
儿童:[
文本(_大陆[索引].大陆),
//如何创建ListView以显示包含以下内容的列:
//_国家[索引]。名称,
//_国家[指数]。首都,
//_国家[索引]。语言,
],
);
})));
}
}
您需要将第二个listview.builder放置在具有定义高度的容器中
Container(
height: 120,
child: ListView.builder(
shrinkWrap: true,
scrollDirection: Axis.horizontal,
itemCount: map.length,
itemBuilder: (context, index) => Column(
children: [
Text(_country.elementAt(index).name),
Text(_country.elementAt(index).capital),
Text(_country.elementAt(index).language),
],
),
),
)
您需要将第二个listview.builder放置在具有定义高度的容器中
Container(
height: 120,
child: ListView.builder(
shrinkWrap: true,
scrollDirection: Axis.horizontal,
itemCount: map.length,
itemBuilder: (context, index) => Column(
children: [
Text(_country.elementAt(index).name),
Text(_country.elementAt(index).capital),
Text(_country.elementAt(index).language),
],
),
),
)
您可以复制粘贴运行下面的完整代码
您可以使用嵌套的
ListView.separated
代码片段
ListView.separated(
separatorBuilder: (BuildContext context, int index) {
return SizedBox(
height: 10,
);
},
shrinkWrap: true,
itemCount: null == _continent ? 0 : _continent.length,
itemBuilder: (context, index) {
return Column(
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
Row(
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
Expanded(
flex: 1, child: Text(_continent[index].continent)),
Expanded(
flex: 2,
child: Container(
height: 50,
child: ListView.separated(
separatorBuilder:
ListView.com(
separatorBuilder:(BuildContext,int索引){
返回大小框(
身高:10,
);
},
收缩膜:对,
itemCount:null==\u大陆?0:\u大陆.length,
itemBuilder:(上下文,索引){
返回列(
mainAxisAlignment:mainAxisAlignment.center,
crossAxisAlignment:crossAxisAlignment.center,
儿童:[
划船(
mainAxisAlignment:mainAxisAlignment.center,
crossAxisAlignment:crossAxisAlignment.center,
儿童:[
扩大(
flex:1,child:Text(_contraction[index].contraction)),
扩大(
弹性:2,
子:容器(
身高:50,
子项:ListView.separated(
分离器生成器:
描述所有细节太长,您可以直接参考完整代码工作演示 完整代码
import 'package:flutter/material.dart';
// To parse this JSON data, do
//
// final continent = continentFromJson(jsonString);
import 'dart:convert';
List<Continent> continentFromJson(String str) =>
List<Continent>.from(json.decode(str).map((x) => Continent.fromJson(x)));
String continentToJson(List<Continent> data) =>
json.encode(List<dynamic>.from(data.map((x) => x.toJson())));
class Continent {
Continent({
this.id,
this.continent,
this.country,
});
int id;
String continent;
List<Country> country;
factory Continent.fromJson(Map<String, dynamic> json) => Continent(
id: json["id"],
continent: json["continent"],
country:
List<Country>.from(json["country"].map((x) => Country.fromJson(x))),
);
Map<String, dynamic> toJson() => {
"id": id,
"continent": continent,
"country": List<dynamic>.from(country.map((x) => x.toJson())),
};
}
class Country {
Country({
this.name,
this.capital,
this.language,
});
String name;
String capital;
List<String> language;
factory Country.fromJson(Map<String, dynamic> json) => Country(
name: json["name"],
capital: json["capital"],
language: List<String>.from(json["language"].map((x) => x)),
);
Map<String, dynamic> toJson() => {
"name": name,
"capital": capital,
"language": List<dynamic>.from(language.map((x) => x)),
};
}
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
visualDensity: VisualDensity.adaptivePlatformDensity,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class ContinentServices {
Future<List<Continent>> getContinent() {
String jsonString = '''
[
{
"id": 1,
"continent": "North America",
"country": [
{
"name": "United States",
"capital": "Washington, D.C.",
"language": [
"English"
]
},
{
"name": "Canada",
"capital": "Ottawa",
"language": [
"English",
"French"
]
}
]
},
{
"id": 2,
"continent": "Europe",
"country": [
{
"name": "Germany",
"capital": "Berlin",
"language": [
"German"
]
}
]
}
]
''';
List<Continent> continentList = continentFromJson(jsonString);
return Future.value(continentList);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
List<Continent> _continent;
@override
void initState() {
super.initState();
ContinentServices().getContinent().then((continents) {
setState(() {
_continent = continents;
});
});
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: ListView.separated(
separatorBuilder: (BuildContext context, int index) {
return SizedBox(
height: 10,
);
},
shrinkWrap: true,
itemCount: null == _continent ? 0 : _continent.length,
itemBuilder: (context, index) {
return Column(
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
Row(
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
Expanded(
flex: 1, child: Text(_continent[index].continent)),
Expanded(
flex: 2,
child: Container(
height: 50,
child: ListView.separated(
separatorBuilder:
(BuildContext context, int index) {
return SizedBox(
width: 10,
);
},
shrinkWrap: true,
scrollDirection: Axis.horizontal,
itemCount: null == _continent
? 0
: _continent[index].country.length,
itemBuilder: (context, countryIndex) {
print(_continent[index]
.country[countryIndex]
.name);
return Row(
mainAxisAlignment:
MainAxisAlignment.center,
crossAxisAlignment:
CrossAxisAlignment.center,
children: <Widget>[
Container(
width: 120,
child: Column(
children: <Widget>[
Text(
_continent[index]
.country[countryIndex]
.name,
style: TextStyle(
color: Colors.red),
),
Text(
_continent[index]
.country[countryIndex]
.capital,
style: TextStyle(
color: Colors.red)),
Expanded(
child: ListView.separated(
separatorBuilder:
(BuildContext context,
int index) {
return SizedBox(
width: 2,
);
},
shrinkWrap: true,
scrollDirection:
Axis.horizontal,
itemCount: null ==
_continent
? 0
: _continent[index]
.country[
countryIndex]
.language
.length,
itemBuilder: (context,
languageIndex) {
return Row(
mainAxisAlignment:
MainAxisAlignment
.spaceEvenly,
children: <Widget>[
Text(
_continent[index]
.country[
countryIndex]
.language[
languageIndex],
style: TextStyle(
color: Colors
.red)),
]);
}),
),
],
),
)
]);
}),
),
)
])
],
);
}));
}
}
导入“包装:颤振/材料.省道”;
//要解析此JSON数据,请执行以下操作
//
//最终大陆=大陆从JSON(jsonString);
导入“dart:convert”;
List fromJSON(字符串str)=>
List.from(json.decode(str.map)((x)=>contraction.fromJson(x));
字符串JSON(列表数据)=>
encode(List.from(data.map((x)=>x.toJson());
阶级大陆{
大陆({
这个身份证,
这个大陆,
这个国家,
});
int-id;
弦大陆;
名单国家;
工厂大陆。fromJson(映射json)=>大陆(
id:json[“id”],
大陆:json[“大陆”],
国家:
List.from(json[“country”].map((x)=>country.fromJson(x)),
);
映射到JSON()=>{
“id”:id,
“大陆”:大陆,
“country”:List.from(country.map((x)=>x.toJson()),
};
}
阶级国家{
国家({
这个名字,
这个首都,,
这种语言,
});
字符串名;
字符串资本;
列表语言;
工厂国家。fromJson(映射json)=>国家(
名称:json[“名称”],
大写:json[“大写”],
语言:List.from(json[“language”].map((x)=>x)),
);
映射到JSON()=>{
“姓名”:姓名,
“资本”:资本,
“语言”:List.from(language.map((x)=>x)),
};
}
void main(){
runApp(MyApp());
}
类MyApp扩展了无状态小部件{
@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(
主样本:颜色。蓝色,
视觉密度:视觉密度。自适应平台密度,
),
主页:MyHomePage(标题:“颤振演示主页”),
);
}
}
类服务{
未来的非洲大陆(){
字符串jsonString='''
[
{
“id”:1,
“大陆”:“北美”,
“国家”:[
{
“名称”:“美国”,
“首都”:“华盛顿特区”,
“语言”:[
“英语”
]
},
{
“姓名”:“加拿大”,
“首都”:“渥太华”,
“语言”:[
“英语”,
“法语”
]
}
]
},
{
“id”:2,
“大陆”:“欧洲”,
“国家”:[
{
“名称”:“德国”,
“首都”:“柏林”,
“语言”:[
“德语”
]
}
]
}
]
''';
List CONTRONLIST=大陆fromJSON(jsonString);
返回Future.value(列表);
}
}
类MyHomePage扩展StatefulWidget{
MyHomePage({Key,this.title}):超级(Key:Key);
最后的字符串标题;
@凌驾
_MyHomePageState createState()=>\u MyHomePageState();
}
类_MyHomePageState扩展状态{
欧洲大陆名单;
@凌驾
void initState(){
super.initState();
服务().getContine