flutter - Column 中的 Listviewbuilder 实现不起作用
问题描述
我想在我的主屏幕上有一个可滚动的列表。我尝试将名为 Cardslist() 的 Listviewbuilder 实现到主屏幕中,但我总是抛出此异常:RenderFlex 子项具有非零弹性,传入的高度约束是无界的。这是主屏幕的代码:
import 'package:biminda_app/Components/cards_list.dart';
import 'package:biminda_app/Components/real_new_finished_card.dart';
import 'package:flutter/material.dart';
import 'package:biminda_app/Components/custom_Buttons.dart';
import 'package:biminda_app/Components/constants.dart';
import 'package:flutter/rendering.dart';
import 'package:biminda_app/Screens/new_card_screen1.dart';
import 'package:biminda_app/Screens/settings.dart';
import 'package:biminda_app/Components/card_data.dart';
import 'package:biminda_app/Components/cards_list.dart';
class HomeScreen extends StatefulWidget {
static const String id = 'home_screen';
@override
_HomeScreenState createState() => _HomeScreenState();
}
class _HomeScreenState extends State<HomeScreen> {
String individualsName;
@override
Widget build(BuildContext context) {
return Scaffold(
body: Column(
crossAxisAlignment: CrossAxisAlignment.start,
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: <Widget>[
Container(
padding: EdgeInsets.fromLTRB(
20,
40,
20,
0,
),
child: TextField(
style: TextStyle(
color: Colors.black,
),
decoration: kTextFieldInputDecoration,
onChanged: (value) {
individualsName = value;
// TODO: Der Input muss das Individum in der Liste
// TODO: erkennen und anzeigen
},
),
),
//TODO HIER
Expanded(
child: Column(
children: <Widget>[
CardsList(),
],
)),
Center(
child: Container(
child: MainButton(
functionality: 'New',
onPressed: () {
Navigator.pushNamed(context, NewCard.id);
}),
),
),
Padding(
padding: const EdgeInsets.all(16.0),
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: <Widget>[
SideButton(
functionality: 'Settings',
onPressed: () {
Navigator.pushNamed(context, Settings.id);
}),
SideButton(
functionality: 'Calendar',
onPressed: () {
Navigator.pushNamed(context, Settings.id);
}),
],
),
),
],
),
);
}
}
这是 Cardslist() 的代码:
class CardsList extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Consumer<CardData>(builder: (context, cardData, child) {
return ListView.builder(
scrollDirection: Axis.vertical,
shrinkWrap: true,
itemBuilder: (context, index) {
final card = cardData.cards[index];
return FinalCardCreation(
finalname: card.cname,
finalbirthday: card.cbirthday,
);
});
});
}
}
创建卡片 FinalCardCreation() 的代码:
class CardFinish extends StatefulWidget {
@override
CardFinishState createState() => CardFinishState();
}
class CardFinishState extends State<CardFinish> {
@override
Widget build(BuildContext context) {
return SizedBox(
height:
MediaQuery.of(context).size.height * 0.5, //<-- set height of the card
child: FinalCardCreation(),
);
}
}
class FinalCardCreation extends StatelessWidget {
String finalname;
String finalbirthday;
FinalCardCreation({
Key key,
@required this.finalname,
@required this.finalbirthday,
}) : super(key: key);
@override
Widget build(BuildContext context) {
return Card(
color: Color(0xFFef9a9a),
margin: EdgeInsets.all(2),
elevation: 8,
shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(22)),
child: Column(
children: <Widget>[
SizedBox(height: 8),
Expanded(
child: FinalCardContent(
name: finalname,
birthday: finalbirthday,
),
)
],
),
);
}
}
class FinalCardContent extends StatelessWidget {
String name;
String birthday;
FinalCardContent({Key key, @required this.name, @required this.birthday})
: super(key: key);
@override
Widget build(BuildContext context) {
return Padding(
padding: const EdgeInsets.all(16.0),
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.stretch,
children: <Widget>[
Padding(
padding: const EdgeInsets.all(8.0),
child: Text(
'$name',
textAlign: TextAlign.center,
style: TextStyle(
fontSize: 50.0,
color: Colors.black,
),
),
),
Padding(
padding: const EdgeInsets.all(8.0),
child: Text(
'$birthday',
textAlign: TextAlign.center,
style: TextStyle(
fontSize: 50.0,
color: Colors.black,
),
),
),
],
),
);
}
}
我试图以多种方式包装我的 Cardslist() 但我总是遇到这个异常。感谢您的时间和回答。
解决方案
Column
是一个高度可以无限增长的小部件。它不会对其子项施加任何高度限制。将sExpanded
包含在其中是一种明智的方式,因为它们适合屏幕上所有可能的空间,但对它们的子元素施加了约束。ListView
Column
Column
您可以删除Column
您的包装CardList
,或者,如果您以后确实需要Column
其他东西,请尝试包装CardList
另一个Expanded
.
推荐阅读
- basic - 基本命令: RIGHT$
- c++ - 如何在 C/C++ 中无错误地运行阿克曼函数?
- reactjs - mapStateToProps 不向道具发送任何内容
- laravel - Laravel Column 已经存在:1060 Duplicate column name
- android - Jetpack 中的权重组成
- matlab - 如何为结构中的多个中级字段分配子级别
- mysql - 从 2 个表中获取数据 - 一次有计数,一次没有
- sql-server - 对多个 CASE 表达式进行分组
- selenium-webdriver - 由于版本问题,Chrome 浏览器无法打开,即使驱动程序已使用 Webdriver-manager 更新
- java - 在 java 中编写自定义 indexOf() 方法