[英]Flutter, checkbox state doesn't change, how to?
我有一个ListView
器,该生成器创建了几个ListTitle
,其中带有一个复选框。
当我在复选框的onChanged
上设置setState
时,该值似乎没有改变。
class ProjectPage extends StatefulWidget {
final project;
ProjectPage({Key key, this.project}) : super(key: key);
@override
_ProjectPageState createState() => new _ProjectPageState();
}
class _ProjectPageState extends State<ProjectPage> {
@override
Widget build(BuildContext context) {
return new Scaffold(
body: new Container(
child: Column(
children: <Widget>[
new Expanded(
child: new ListView.builder(
itemBuilder: (BuildContext context, int index) => new ItemsItem(item: widget.project.items[index]),
itemCount: widget.project.items.length,
),
),
],
),
),
);
}
}
class ItemsItem extends StatefulWidget {
final item;
ItemsItem({Key key, this.item}) : super(key: key);
@override
_ItemsItemState createState() => new _ItemsItemState();
}
class _ItemsItemState extends State<ItemsItem> {
final GlobalKey<ScaffoldState> _mainState = new GlobalKey<ScaffoldState>();
@override
Widget build(BuildContext context) {
bool _isCompleted = widget.item.isCompleted;
return new ListTile(
key: _mainState,
title: new Row(
children: <Widget>[
new Expanded(child: new Text(widget.item.name)),
new Checkbox(
value: _isCompleted,
onChanged: (bool newValue) {
setState(() {
_isCompleted = newValue;
});
},
),
],
),
);
}
}
这似乎并没有改变价值
setState(() {
_isCompleted = newValue;
});
有任何想法吗?
编辑:物品类
class Item {
final int id;
final String name;
final bool isCompleted;
Item({
this.id,
this.name,
this.isCompleted,
});
Item.fromJson(Map json)
: id = json['id'],
name = json['name'],
isCompleted = json['isCompleted'],
set isCompleted(bool value) {
isCompleted = value;
}
}
_isCompleted是build方法内的局部变量。 当复选框的状态更改时,可以将局部变量设置为新值。 setState导致再次调用build方法,该方法从widget.item.isCompleted获取旧的和未更改的值。 您需要将widget.item.isCompleted设置为新的更改值:
setState(() {
widget.item.isCompleted = newValue;
});
顺便说一句,由于您的ItemsItem只是一个ListTile,其中包含带有文本和Checkbox的行,因此您应该使用内置小部件CheckboxListTile
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