android - 如何重建 listview.builder？
问题描述
我需要重建我的列表视图，因为它只维护第一个构建，除非我重置应用程序。我有一个底部表单弹出，让我选择时间并将我导航到 listview.builder 构建的新页面。如果我退出页面，选择新选项，然后返回页面，它不会更新。这是一个例子：
相关代码：
final selectTimesTextStyle = TextStyle(
fontSize: 20,
fontWeight: FontWeight.bold,
);
final List classBools = [
checkedPreBallet,
checkedBeginningBallet,
checkedIntermediateBallet,
checkedAdvancedBallet,
checkedJazz,
checkedPC,
];
final List<String> preballetItems = [
'Wednesday 3:00-4:00',
'Friday 3:00-3:35',
];
final List<String> privateClassesItems = [
'Mondays, Schedule Via Email',
];
final List<String> intermediateBalletItems = [
'Tuesday 5:00-6:00',
'Thursday 5:00-6:00',
'Saturday 10:00-11:00',
];
final List<String> advancedBalletItems = [
'Tuesday 6:00-7:00',
'Thursday 6:00-7:00',
];
final List<String> beginningBalletItems = [
'Wednesday 3:45-4:45',
'Friday 3:45-4:45',
];
final List<String> jazzItems = [
'Thursday 4:00-5:00',
];
final List<List> listOfLists = [
preballetItems,
beginningBalletItems,
intermediateBalletItems,
advancedBalletItems,
jazzItems,
privateClassesItems,
];
List<String> valueChoose = [
'Wednesday 3:00-4:00',
'Wednesday 3:45-4:45',
'Tuesday 5:00-6:00',
'Tuesday 6:00-7:00',
'Thursday 4:00-5:00',
'Mondays, Schedule Via Email',
];
class TimeSelection extends StatelessWidget {
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
leading: InkWell(
onTap: () => {
Navigator.of(context).pop(),
currentIndex = 2,
checkedPreBallet = false,
checkedBeginningBallet = false,
checkedIntermediateBallet = false,
checkedAdvancedBallet = false,
checkedJazz = false,
checkedPC = false,
},
child: Container(
child: Icon(Icons.arrow_back),
),
),
title: Text('Select Times'),
centerTitle: true,
),
body: StatefulBuilder(
builder: (context, setState) => Column(
children: [
Expanded(
child: ListView.builder(
itemCount: 6,
itemBuilder: (context, index) => Visibility(
maintainState: false,
visible: classBools[index],
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: [
Container(
child: Text(
buttonTitles[index],
style: selectTimesTextStyle,
),
width: MediaQuery.of(context).size.width * 0.50,
),
Container(
width: MediaQuery.of(context).size.width * 0.40,
child: DropdownButton(
isExpanded: true,
underline: SizedBox(),
dropdownColor: Colors.white,
value: valueChoose[index],
onChanged: (newValue) => {
setState(() {
valueChoose[index] = newValue;
})
},
items: listOfLists[index]
.map((e) => DropdownMenuItem(
onTap: () => {
classBools[index] = true,
},
child: Text(e),
value: e,
))
.toList(),
),
),
],
),
),
),
),
Padding(
padding: const EdgeInsets.symmetric(
horizontal: 120,
vertical: 15,
),
child: Container(
decoration: BoxDecoration(
gradient: LinearGradient(
begin: Alignment.topCenter,
end: Alignment.bottomCenter,
stops: [
0.00005,
1,
],
colors: [
Theme.of(context).secondaryHeaderColor,
Theme.of(context).primaryColor,
]),
boxShadow: [
BoxShadow(color: Colors.black54, offset: Offset(3, 3)),
],
color: Colors.purpleAccent,
borderRadius: BorderRadius.circular(15),
),
child: InkWell(
onTap: () => {},
child: Padding(
padding: EdgeInsets.all(16),
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: [
Text('PayPal'),
],
),
),
),
),
),
],
),
),
);
}
}
bool checkedPreBallet = false;
bool checkedBeginningBallet = false;
bool checkedIntermediateBallet = false;
bool checkedAdvancedBallet = false;
bool checkedJazz = false;
bool checkedPC = false;
final List<String> buttonTitles = [
'Pre-Ballet',
'Beginning Ballet',
'Intermediate Ballet',
'Advanced Ballet',
'Jazz',
'Private Classes',
];
class RegisterPage extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Scaffold(
body: Column(
children: [
Divider(),
Text('hello'),
Divider(),
RegisterCards(),
],
),
);
}
}
class RegisterCards extends StatefulWidget {
@override
_RegisterCardsState createState() => _RegisterCardsState();
}
class _RegisterCardsState extends State<RegisterCards> {
@override
Widget build(BuildContext context) {
return Padding(
padding: const EdgeInsets.symmetric(
horizontal: 30,
),
child: Container(
decoration: BoxDecoration(
gradient: LinearGradient(
begin: Alignment.topCenter,
end: Alignment.bottomCenter,
stops: [
0.00005,
1,
],
colors: [
Theme.of(context).secondaryHeaderColor,
Theme.of(context).primaryColor,
]),
boxShadow: [
BoxShadow(color: Colors.black54, offset: Offset(3, 3)),
],
color: Colors.purpleAccent,
borderRadius: BorderRadius.circular(15),
),
child: InkWell(
onTap: () => onButtonPressed(context),
child: Padding(
padding: EdgeInsets.all(16),
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: [
Text('Register Here'),
],
),
),
),
),
);
}
}
class ClassListWidget extends StatefulWidget {
@override
_ClassListWidgetState createState() => _ClassListWidgetState();
}
class _ClassListWidgetState extends State<ClassListWidget> {
@override
Widget build(BuildContext context) {
return StatefulBuilder(
builder: (context, setState) => Column(
children: [
CheckboxListTile(
value: checkedPreBallet,
onChanged: (value) => {
setState(() {
checkedPreBallet = value;
})
},
title: Text('Pre-Ballet'),
checkColor: Theme.of(context).scaffoldBackgroundColor,
activeColor: Theme.of(context).primaryColor,
secondary: Icon(PokemonIcons.i004_charmander),
controlAffinity: ListTileControlAffinity.leading,
tristate: false,
),
CheckboxListTile(
value: checkedBeginningBallet,
onChanged: (value) => {
setState(() {
checkedBeginningBallet = value;
})
},
title: Text('Beginning Ballet'),
checkColor: Theme.of(context).scaffoldBackgroundColor,
activeColor: Theme.of(context).primaryColor,
secondary: Icon(PokemonIcons.i004_charmander),
controlAffinity: ListTileControlAffinity.leading,
tristate: false,
),
CheckboxListTile(
value: checkedIntermediateBallet,
onChanged: (value) => {
setState(() {
checkedIntermediateBallet = value;
})
},
title: Text('Intermediate Ballet'),
checkColor: Theme.of(context).scaffoldBackgroundColor,
activeColor: Theme.of(context).primaryColor,
secondary: Icon(PokemonIcons.i004_charmander),
controlAffinity: ListTileControlAffinity.leading,
tristate: false,
),
CheckboxListTile(
value: checkedAdvancedBallet,
onChanged: (value) => {
setState(() {
checkedAdvancedBallet = value;
})
},
title: Text('Advanced Ballet'),
checkColor: Theme.of(context).scaffoldBackgroundColor,
activeColor: Theme.of(context).primaryColor,
secondary: Icon(PokemonIcons.i004_charmander),
controlAffinity: ListTileControlAffinity.leading,
tristate: false,
),
CheckboxListTile(
value: checkedJazz,
onChanged: (value) => {
setState(() {
checkedJazz = value;
})
},
title: Text('Jazz'),
checkColor: Theme.of(context).scaffoldBackgroundColor,
activeColor: Theme.of(context).primaryColor,
secondary: Icon(PokemonIcons.i004_charmander),
controlAffinity: ListTileControlAffinity.leading,
tristate: false,
),
CheckboxListTile(
value: checkedPC,
onChanged: (value) => {
setState(() {
checkedPC = value;
})
},
title: Text('Private Classes'),
checkColor: Theme.of(context).scaffoldBackgroundColor,
activeColor: Theme.of(context).primaryColor,
secondary: Icon(PokemonIcons.i004_charmander),
controlAffinity: ListTileControlAffinity.leading,
tristate: false,
),
],
),
);
}
}
void onButtonPressed(context) {
showModalBottomSheet(
isScrollControlled: false,
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.only(
topLeft: Radius.circular(15),
topRight: Radius.circular(15),
),
),
backgroundColor: Theme.of(context).scaffoldBackgroundColor,
context: context,
builder: (context) => StatefulBuilder(
builder: (BuildContext context, setState) => Container(
child: Column(
children: [
ClassListWidget(),
Padding(
padding: const EdgeInsets.symmetric(
horizontal: 15,
),
child: Container(
decoration: BoxDecoration(
gradient: LinearGradient(
begin: Alignment.topCenter,
end: Alignment.bottomCenter,
stops: [
0.00005,
1,
],
colors: [
Theme.of(context).secondaryHeaderColor,
Theme.of(context).primaryColor,
]),
boxShadow: [
BoxShadow(color: Colors.black54, offset: Offset(3, 3)),
],
color: Colors.purpleAccent,
borderRadius: BorderRadius.circular(15),
),
child: InkWell(
onTap: () => {
Navigator.push(context, MaterialPageRoute(
builder: (context) => TimeSelection(),
)),
},
child: Padding(
padding: EdgeInsets.all(14),
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: [
Text('Select Times'),
],
),
),
),
),
),
],
),
),
),
);
}
解决方案
检查它是否符合您的需要。
import 'package:flutter/material.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
// This is the theme of your application.
//
// Try running your application with "flutter run". You'll see the
// application has a blue toolbar. Then, without quitting the app, try
// changing the primarySwatch below to Colors.green and then invoke
// "hot reload" (press "r" in the console where you ran "flutter run",
// or simply save your changes to "hot reload" in a Flutter IDE).
// Notice that the counter didn't reset back to zero; the application
// is not restarted.
primarySwatch: Colors.blue,
),
home: TimeSelection(),
);
}
}
// model class for your ballet
class Ballet {
final String balletName;
final List<String> timeSchedules;
final String description;
String selectedTime;
bool isSelected = false;
Ballet({
this.balletName,
this.timeSchedules,
isSelected,
this.description = '',
this.selectedTime
}) {selectedTime ??= this.timeSchedules[0];}
}
List<Ballet> balletItems = <Ballet>[
Ballet(
balletName: "Pre-Ballet",
timeSchedules: [
'Wednesday 3:00-4:00',
'Friday 3:00-3:35',
],
),
Ballet(
balletName: "Private Classes",
timeSchedules: [
'Mondays',
],
description: 'Scheduled Via Email'
),
Ballet(
balletName: "Intermediate Ballet",
timeSchedules: [
'Tuesday 5:00-6:00',
'Thursday 5:00-6:00',
'Saturday 10:00-11:00',
],
),
Ballet(
balletName: "Advance Ballet",
timeSchedules: [
'Tuesday 6:00-7:00',
'Thursday 6:00-7:00',
],
),
Ballet(
balletName: "Beginning Ballet",
timeSchedules: [
'Wednesday 3:45-4:45',
'Friday 3:45-4:45',
],
),
Ballet(
balletName: "Jazz Ballet",
timeSchedules: [
'Thursday 4:00-5:00',
],
)
];
class TimeSelection extends StatefulWidget {
@override
_TimeSelectionState createState() => _TimeSelectionState();
}
class _TimeSelectionState extends State<TimeSelection> {
@override
Widget build(BuildContext context) {
return Scaffold(
body: Column(
crossAxisAlignment: CrossAxisAlignment.center,
children: [
Center(
child: Column(
children: [
Text('hello there', style: Theme.of(context).textTheme.headline4),
ElevatedButton(child: Text('Register Here',), onPressed: () {},),
],
),
),
Expanded(
child: ListView.builder(
itemCount: balletItems.length+1 ,
itemBuilder: (context, index){
if (index < balletItems.length) {
Ballet balletItem = balletItems[index];
return ListTile(leading: Checkbox(
value: balletItem.isSelected,
onChanged: (value) {
setState((){
balletItem.isSelected = value;
});
},),
title: Text(balletItem.balletName),
trailing: Icon(Icons.auto_awesome),
);}
else{
return Container(
margin: const EdgeInsets.symmetric(horizontal: 20.0),
child: ElevatedButton(
onPressed: () {
Navigator.of(context).push(MaterialPageRoute(builder: (context) => SelectTimes(),));
},
child: Text('Select Times'),
),
);}
},
),
)
],
),
drawer: Drawer(),
appBar: AppBar(title: Text("Class Registration"),),
);
}
}
class SelectTimes extends StatefulWidget {
@override
_SelectTimesState createState() => _SelectTimesState();
}
class _SelectTimesState extends State<SelectTimes> {
List<Ballet> selectedBalletItems;
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: Text('Select Times'),),
body: Padding(
padding: const EdgeInsets.all(10.0),
child: Column(
children: [
Expanded(
child: ListView.builder(
itemCount: selectedBalletItems.length,
itemBuilder: (context, index) {
Ballet selectedBalletItem = selectedBalletItems[index];
return _listTile(selectedBalletItem);
},
),
),
ElevatedButton(child: Padding(
padding: const EdgeInsets.all(8.0),
child: Text("PayPal", style: Theme.of(context).textTheme.headline4,
),
),
onPressed: () {},)
],
),
)
);
}
Widget _listTile(Ballet selectedBalletItem) {
return ListTile(
title: Text(selectedBalletItem.balletName),
subtitle: Text(selectedBalletItem.description , style: Theme.of(context).textTheme.bodyText2.copyWith(color: Colors.grey[500])),
trailing: DropdownButton<String>(
value: selectedBalletItem.selectedTime,
items: selectedBalletItem.timeSchedules.map((timeSchedule) {
return DropdownMenuItem(value: timeSchedule, child: Text(timeSchedule));
} ).toList(),
onChanged: (value) {
setState(() {
selectedBalletItem.selectedTime = value;
});
},
)
);
}
@override
void initState() {
super.initState();
selectedBalletItems = balletItems.where((e) => e.isSelected).toList();
}
}
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