我正在尝试从api中获取数据，并将其显示在我的卡片列表中。但是每当我加载应用程序时，我都会收到此错误
'borderRadius != null
I/flutter (28205): || clipper != null': is not true.
，我不确定该如何解决。
我尝试在发生错误的行中进行更改，但错误保持不变。
import 'dart:convert';
import 'package:flutter/material.dart';
import 'package:news/model/businessModel.dart';
import 'package:http/http.dart' as http;
class Discover extends StatefulWidget {
final Source source;
Discover({Key key, this.source}) : super(key: key);
@override
_DiscoverState createState() => _DiscoverState();
}
class _DiscoverState extends State<Discover> {
String API_KEY = '0ca85f22bce44565ba4fee8d2224adb5';
Future<List<Articles>> fetchArticleBySource() async {
final response = await http.get(
'https://newsapi.org/v2/top-headlines?
category=business&language=en&apiKey=${API_KEY}');
if (response.statusCode == 200) {
List articles = json.decode(response.body)['articles'];
return articles.map((article) => new
Articles.fromJson(article)).toList();
} else {
throw Exception('Failed to load article list');
}
}
var list_articles;
var refreshKey = GlobalKey<RefreshIndicatorState>();
@override
void initState() {
// TODO: implement initState
super.initState();
refreshListArticle();
}
Future<Null> refreshListArticle() async {
refreshKey.currentState?.show(atTop: false);
setState(() {
list_articles = fetchArticleBySource();
});
}
@override
Widget build(BuildContext context) {
return Padding(
padding: const EdgeInsets.only(
left: 15.0,
top: 15.0,
right: 15.0,
),
child: ListView(
children: <Widget>[
topArea(),
SizedBox(
height: 10.0,
),
slideCard(),
SizedBox(
height: 5.0,
),
Padding(
padding: const EdgeInsets.only(left: 4.0),
child: Divider(),
),
recentNews(),
],
),
);
}
Widget topArea() {
return Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: <Widget>[
Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Text(
"WEDNESDAY, NOVEMBER 29",
style: TextStyle(color: Colors.grey, fontWeight:
FontWeight.bold),
),
SizedBox(
height: 5.0,
),
Text(
"TOP NEWS",
style: TextStyle(fontSize: 25.0, fontWeight: FontWeight.bold),
),
],
),
Hero(
tag: 'img',
child: InkWell(
//onTap: () => Navigator.push(context, MaterialPageRoute(builder:
(context) => )),
child: CircleAvatar(
radius: 25.0,
//backgroundColor: Colors.transparent,
backgroundImage: NetworkImage(
"https://images.pexels.com/photos/1138409/pexels-photo-
1138409.jpeg?auto=compress&cs=tinysrgb&dpr=2&h=750&w=1260",
),
),
),
),
],
);
}
Widget slideCard() {
return FutureBuilder<List<Articles>>(
future: list_articles,
builder: (context, snapshot) {
if (snapshot.hasError) {
return Text("${snapshot.error}");
} else if (snapshot.hasData) {
List<Articles> articles = snapshot.data;
return Container(
height: 310.0,
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(0.0),
),
child: ListView(
scrollDirection: Axis.horizontal,
children: articles
.map((article) => GestureDetector(
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Expanded(
child: Card(
elevation: 3.0,
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(10.0),
),
child: ClipRRect(
clipper: ,
child: article.urlToImage != null
? Image.network(article.urlToImage)
: Image.asset('images/logo.jpg'),
),
),
),
SizedBox(
height: 10.0,
),
Padding(
padding: const EdgeInsets.only(left: 4.0),
child: Text("${article.title}",
style: TextStyle(
color: Colors.blueAccent,
fontSize: 12.0,
fontWeight: FontWeight.bold),
),
),
SizedBox(
height: 10.0,
),
Padding(
padding: const EdgeInsets.only(left: 4.0),
child: Text(
"${article.description}",
style: TextStyle(
color: Colors.black,
fontSize: 14.0,
fontWeight: FontWeight.bold),
),
),
],
),
))
.toList(),
),
);
}
return CircularProgressIndicator();
},
);
}
Widget recentNews() {
return Column(
children: <Widget>[
Padding(
padding: const EdgeInsets.only(left: 4.0),
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: <Widget>[
Text(
"Recent News",
style: TextStyle(fontSize: 20.0, fontWeight: FontWeight.bold),
),
Align(
alignment: Alignment.centerRight,
child: Text(
"See All",
style: TextStyle(color: Colors.lightBlueAccent),
),
)
],
),
),
SizedBox(
height: 7.0,
),
Container(
height: 200.0,
child: ListView(
scrollDirection: Axis.horizontal,
children: <Widget>[
Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Expanded(
child: Card(
elevation: 3.0,
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(10.0),
),
child: ClipRRect(
child: Image.network(
"https://images.pexels.com/photos/935789/pexels-photo-935789.jpeg?auto=compress&cs=tinysrgb&dpr=2&h=750&w=1260"),
borderRadius: BorderRadius.circular(10.0),
),
),
),
SizedBox(
height: 10.0,
),
Padding(
padding: const EdgeInsets.only(left: 4.0),
child: Text(
"STARTUPS",
style: TextStyle(
color: Colors.blueAccent,
fontSize: 12.0,
fontWeight: FontWeight.bold),
),
),
SizedBox(
height: 10.0,
),
Padding(
padding: const EdgeInsets.only(left: 4.0),
child: Text(
"Top startups that are \nchanging the way we travel",
style: TextStyle(
color: Colors.black,
fontSize: 15.0,
fontWeight: FontWeight.bold),
),
),
],
),
Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Expanded(
child: Card(
elevation: 3.0,
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(10.0),
),
child: ClipRRect(
child: Image.network(
"https://images.pexels.com/photos/935789/pexels-photo-935789.jpeg?auto=compress&cs=tinysrgb&dpr=2&h=750&w=1260"),
borderRadius: BorderRadius.circular(10.0),
),
),
),
SizedBox(
height: 10.0,
),
Padding(
padding: const EdgeInsets.only(left: 4.0),
child: Text(
"STARTUPS",
style: TextStyle(
color: Colors.blueAccent,
fontSize: 12.0,
fontWeight: FontWeight.bold),
),
),
SizedBox(
height: 10.0,
),
Padding(
padding: const EdgeInsets.only(left: 4.0),
child: Text(
"Top startups that are \nchanging the way we travel",
style: TextStyle(
color: Colors.black,
fontSize: 15.0,
fontWeight: FontWeight.bold),
),
),
],
),
Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Expanded(
child: Card(
elevation: 3.0,
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(10.0),
),
child: ClipRRect(
child: Image.network(
"https://images.pexels.com/photos/935789/pexels-photo-935789.jpeg?auto=compress&cs=tinysrgb&dpr=2&h=750&w=1260"),
borderRadius: BorderRadius.circular(10.0),
),
),
),
SizedBox(
height: 10.0,
),
Padding(
padding: const EdgeInsets.only(left: 4.0),
child: Text(
"STARTUPS",
style: TextStyle(
color: Colors.blueAccent,
fontSize: 12.0,
fontWeight: FontWeight.bold),
),
),
SizedBox(
height: 10.0,
),
Padding(
padding: const EdgeInsets.only(left: 4.0),
child: Text(
"Top startups that are \nchanging the way we travel",
style: TextStyle(
color: Colors.black,
fontSize: 15.0,
fontWeight: FontWeight.bold),
),
),
],
),
Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Expanded(
child: Card(
elevation: 3.0,
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(10.0),
),
child: ClipRRect(
child: Image.network(
"https://images.pexels.com/photos/935789/pexels-photo-935789.jpeg?auto=compress&cs=tinysrgb&dpr=2&h=750&w=1260"),
borderRadius: BorderRadius.circular(10.0),
),
),
),
SizedBox(
height: 10.0,
),
Padding(
padding: const EdgeInsets.only(left: 4.0),
child: Text(
"STARTUPS",
style: TextStyle(
color: Colors.blueAccent,
fontSize: 12.0,
fontWeight: FontWeight.bold),
),
),
SizedBox(
height: 10.0,
),
Padding(
padding: const EdgeInsets.only(left: 4.0),
child: Text(
"Top startups that are\n changing the way we travel",
style: TextStyle(
color: Colors.black,
fontSize: 15.0,
fontWeight: FontWeight.bold),
),
),
],
),
],
),
),
],
);
}
}
答案 0 :(得分：2)
如果仔细观察，您会看到一个ClipRRect的裁剪器为空，因此为空。
根据错误消息，如果clipper为null，则必须指定borderRadius。
child: ClipRRect(
clipper: ,
child: article.urlToImage != null
? Image.network(article.urlToImage)
: Image.asset('images/logo.jpg'),
),