如何从Flutter中的AnimatedList中清除所有项目 [英] How to clear all items from an AnimatedList in Flutter
本文介绍了如何从Flutter中的AnimatedList中清除所有项目的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我试图像在Android中为RecyclerView适配器所做的那样,在AnimatedList上预生成所有更新操作。但是当我要清除所有数据时,我不知道该怎么做。
I was trying to preproduce all of the update operations on an AnimatedList like I have done for a RecyclerView adapter in Android. But when I got to clearing all of the data, I couldn't figure out how to do it.
如果我这样做
setState(() {
_data.clear();
});
然后清除了支持数据,但是GlobalKey的当前状态仍然不知道更改,并且上面没有 clear()
方法。
then the backing data is cleared but the GlobalKey's current state still doesn't know about the change, and there is no clear()
method on it.
补充代码
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
home: Scaffold(
appBar: AppBar(title: Text('Update AnimatedList data')),
body: BodyWidget(),
),
);
}
}
class BodyWidget extends StatefulWidget {
@override
BodyWidgetState createState() {
return new BodyWidgetState();
}
}
class BodyWidgetState extends State<BodyWidget> {
// the GlobalKey is needed to animate the list
final GlobalKey<AnimatedListState> _listKey = GlobalKey();
// backing data
List<String> _data = ['Horse', 'Cow', 'Camel', 'Sheep', 'Goat'];
@override
Widget build(BuildContext context) {
return Column(
children: <Widget>[
SizedBox(
height: 400,
child: AnimatedList(
key: _listKey,
initialItemCount: _data.length,
itemBuilder: (context, index, animation) {
return _buildItem(_data[index], animation);
},
),
),
RaisedButton(
child: Text(
'Clear all items',
style: TextStyle(fontSize: 20),
),
onPressed: () {
_clearAllItems();
},
)
],
);
}
Widget _buildItem(String item, Animation animation) {
return SizeTransition(
sizeFactor: animation,
child: Card(
child: ListTile(
title: Text(
item,
style: TextStyle(fontSize: 20),
),
),
),
);
}
void _clearAllItems() {
_data.clear();
// no such method
_listKey.currentState.clear();
}
}
推荐答案
您必须手动删除 _listKey.currentState
中的项目
You have to remove item in _listKey.currentState
manually
示例代码:
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
home: Scaffold(
appBar: AppBar(title: Text('Update AnimatedList data')),
body: BodyWidget(),
),
);
}
}
class BodyWidget extends StatefulWidget {
@override
BodyWidgetState createState() {
return new BodyWidgetState();
}
}
class BodyWidgetState extends State<BodyWidget> {
// the GlobalKey is needed to animate the list
final GlobalKey<AnimatedListState> _listKey = GlobalKey();
// backing data
List<String> _data = ['Horse', 'Cow', 'Camel', 'Sheep', 'Goat'];
@override
Widget build(BuildContext context) {
return Column(
children: <Widget>[
SizedBox(
height: 400,
child: AnimatedList(
key: _listKey,
initialItemCount: _data.length,
itemBuilder: (context, index, animation) {
return _buildItem(_data[index], animation);
},
),
),
RaisedButton(
child: Text(
'Clear all items',
style: TextStyle(fontSize: 20),
),
onPressed: () {
_clearAllItems();
},
)
],
);
}
Widget _buildItem(String item, Animation animation) {
return SizeTransition(
sizeFactor: animation,
child: Card(
child: ListTile(
title: Text(
item,
style: TextStyle(fontSize: 20),
),
),
),
);
}
void _clearAllItems() {
for (var i = 0; i <= _data.length - 1; i++) {
_listKey.currentState.removeItem(0,
(BuildContext context, Animation<double> animation) {
return Container();
});
}
_data.clear();
}
}
这篇关于如何从Flutter中的AnimatedList中清除所有项目的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!
查看全文