Flutter 从数组中删除特定项会删除UI中的错误项
我为此挣扎了几天,但还是想不出来。我有一个简单的小部件,我想在其中动态添加和删除输入(对于集合/重复)。问题是,如果我要删除第一项,那么最后一项将从UI中删除 我已经为应用程序创建了一个省道板: 我的主要目标。省道:Flutter 从数组中删除特定项会删除UI中的错误项,flutter,dart,Flutter,Dart,我为此挣扎了几天,但还是想不出来。我有一个简单的小部件,我想在其中动态添加和删除输入(对于集合/重复)。问题是,如果我要删除第一项,那么最后一项将从UI中删除 我已经为应用程序创建了一个省道板: 我的主要目标。省道: import 'package:flutter/material.dart'; final Color darkBlue = Color.fromARGB(255, 18, 32, 47); void main() { runApp(MyApp()); } class M
import 'package:flutter/material.dart';
final Color darkBlue = Color.fromARGB(255, 18, 32, 47);
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
theme: ThemeData.dark().copyWith(scaffoldBackgroundColor: darkBlue),
debugShowCheckedModeBanner: false,
home: Scaffold(
body: Center(
child: MyWidget(),
),
),
);
}
}
class MyWidget extends StatelessWidget {
@override
Widget build(BuildContext context) {
return SetBuilderWidget();
}
}
class TempSet {
int weight;
int rep;
int order;
TempSet(this.order, this.weight, this.rep);
}
class SetBuilderWidget extends StatefulWidget {
@override
State<StatefulWidget> createState() => _SetBuilderWidgetState();
}
class _SetBuilderWidgetState extends State<SetBuilderWidget> {
final sets = [];
final List<TempSet> tempSet = [];
Widget _row(int index) {
return Row(
children: <Widget>[
Text("Set $index"),
Flexible(
child: Padding(
padding: const EdgeInsets.symmetric(horizontal: 40),
child: TextField(
decoration: InputDecoration(
labelText: "Rep count",
),
),
),
),
IconButton(
icon: Icon(Icons.delete),
onPressed: () => _removeSet(index),
),
],
);
}
List<Widget> _rows() {
return tempSet.map((s) => _row(s.order)).toList();
}
void _addSet() {
if (tempSet.length == 0) {
tempSet.add(TempSet(0, null, null));
} else {
final lastSet = tempSet.last;
tempSet.add(TempSet(tempSet.indexOf(lastSet) + 1, null, null));
}
}
void _removeSet(int index) {
setState(() {
tempSet.removeAt(index);
_updateIndexes();
});
}
void _updateIndexes() {
tempSet.asMap().forEach((index, s) {
s.order = index;
});
}
@override
void initState() {
_addSet();
super.initState();
}
@override
Widget build(BuildContext context) {
return Column(
children: <Widget>[
..._rows(),
RaisedButton(
onPressed: () {
setState(() {
_addSet();
});
},
child: Text("Add set"),
)
],
);
}
}
导入“包装:颤振/材料.省道”;
最终颜色深蓝色=颜色。来自argb(255,18,32,47);
void main(){
runApp(MyApp());
}
类MyApp扩展了无状态小部件{
@凌驾
小部件构建(构建上下文){
返回材料PP(
主题:ThemeData.dark().copyWith(脚手架背景颜色:深蓝色),
debugShowCheckedModeBanner:false,
家:脚手架(
正文:中(
子项:MyWidget(),
),
),
);
}
}
类MyWidget扩展了无状态Widget{
@凌驾
小部件构建(构建上下文){
返回SetBuilderWidget();
}
}
班级临时工{
整数权重;
国际代表;
整数阶;
TempSet(this.order、this.weight、this.rep);
}
类SetBuilderWidget扩展StatefulWidget{
@凌驾
State createState()=>\u SetBuilderWidgetState();
}
类_SetBuilderWidgetState扩展状态{
最终集=[];
最终列表tempSet=[];
小部件_行(整数索引){
返回行(
儿童:[
文本(“设置$index”),
灵活的(
孩子:填充(
填充:常量边集。对称(水平:40),
孩子:TextField(
装饰:输入装饰(
labelText:“代表计数”,
),
),
),
),
图标按钮(
图标:图标(Icons.delete),
按下时:()=>\u移除设置(索引),
),
],
);
}
列表_行(){
返回tempSet.map((s)=>u行(s.order)).toList();
}
void _addSet(){
如果(tempSet.length==0){
add(tempSet(0,null,null));
}否则{
最终lastSet=tempSet.last;
add(tempSet(tempSet.indexOf(lastSet)+1,null,null));
}
}
void _removeSet(整数索引){
设置状态(){
tempSet.removeAt(索引);
_更新索引();
});
}
void _updateIndexes(){
tempSet.asMap().forEach((索引,s){
s、 顺序=索引;
});
}
@凌驾
void initState(){
_addSet();
super.initState();
}
@凌驾
小部件构建(构建上下文){
返回列(
儿童:[
…_行(),
升起的按钮(
已按下:(){
设置状态(){
_addSet();
});
},
子项:文本(“添加集”),
)
],
);
}
}
问题:
import 'package:flutter/material.dart';
final Color darkBlue = Color.fromARGB(255, 18, 32, 47);
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
theme: ThemeData.dark().copyWith(scaffoldBackgroundColor: darkBlue),
debugShowCheckedModeBanner: false,
home: Scaffold(
body: Center(
child: MyWidget(),
),
),
);
}
}
class MyWidget extends StatelessWidget {
@override
Widget build(BuildContext context) {
return SetBuilderWidget();
}
}
class TempSet {
int weight;
int rep;
int order;
TempSet(this.order, this.weight, this.rep);
}
class SetBuilderWidget extends StatefulWidget {
@override
State<StatefulWidget> createState() => _SetBuilderWidgetState();
}
class _SetBuilderWidgetState extends State<SetBuilderWidget> {
final sets = [];
final List<TempSet> tempSet = [];
Widget _row(int index) {
return Row(
children: <Widget>[
Text("Set $index"),
Flexible(
child: Padding(
padding: const EdgeInsets.symmetric(horizontal: 40),
child: TextField(
decoration: InputDecoration(
labelText: "Rep count",
),
),
),
),
IconButton(
icon: Icon(Icons.delete),
onPressed: () => _removeSet(index),
),
],
);
}
List<Widget> _rows() {
return tempSet.map((s) => _row(s.order)).toList();
}
void _addSet() {
if (tempSet.length == 0) {
tempSet.add(TempSet(0, null, null));
} else {
final lastSet = tempSet.last;
tempSet.add(TempSet(tempSet.indexOf(lastSet) + 1, null, null));
}
}
void _removeSet(int index) {
setState(() {
tempSet.removeAt(index);
_updateIndexes();
});
}
void _updateIndexes() {
tempSet.asMap().forEach((index, s) {
s.order = index;
});
}
@override
void initState() {
_addSet();
super.initState();
}
@override
Widget build(BuildContext context) {
return Column(
children: <Widget>[
..._rows(),
RaisedButton(
onPressed: () {
setState(() {
_addSet();
});
},
child: Text("Add set"),
)
],
);
}
}
您的代码有一系列问题。首先,您使用
列
来显示可能比视图更大的项目列表,而使用列
则无法滚动该列表。这也意味着您的添加集
按钮最终可能会被隐藏。使用ListView.builder
将是实现您想要构建的内容的最合适的方法,对于addset
按钮,使用FloatingActionButton
。请检查我在下面编写的代码,以了解我根据您的原始代码和目的提出的实现示例:
class MainExerciseApp extends StatefulWidget {
@override
_MainExerciseAppState createState() => _MainExerciseAppState();
}
class _MainExerciseAppState extends State<MainExerciseApp> {
int currentIndex = 0;
List<ExerciseSet> setList = [];
@override
Widget build(BuildContext context) {
return MaterialApp(
theme: ThemeData.dark().copyWith(scaffoldBackgroundColor: Color.fromARGB(255, 18, 32, 47)),
debugShowCheckedModeBanner: false,
home: Scaffold(
body: Center(
child: SetList(
setList: setList,
removeSet: _removeSet,
),
),
floatingActionButton: FloatingActionButton(
child: Icon(Icons.add),
onPressed: _addSet
),
),
);
}
void _addSet(){
currentIndex++;
setState(() {
setList.add(ExerciseSet(
index: currentIndex,
reps: 0
));
});
}
void _removeSet(ExerciseSet exerciseSet){
setState(() {
setList.remove(exerciseSet);
});
}
}
class SetList extends StatefulWidget {
final List<ExerciseSet> setList;
final Function removeSet;
SetList({
@required this.setList,
@required this.removeSet,
});
@override
_SetListState createState() => _SetListState();
}
class _SetListState extends State<SetList> {
@override
Widget build(BuildContext context) {
return ListView.builder(
itemCount: widget.setList.length,
itemBuilder: (context, index) {
return Row(
children: <Widget>[
Text("Set ${widget.setList[index].index.toString()}"),
Flexible(
child: Padding(
padding: const EdgeInsets.symmetric(horizontal: 40),
child: TextFormField(
initialValue: widget.setList[index].reps.toString(),
decoration: InputDecoration(
labelText: "Rep count",
),
),
),
),
IconButton(
icon: Icon(Icons.delete),
onPressed: () => widget.removeSet(widget.setList[index]),
),
],
);
}
);
}
}
class ExerciseSet {
int index;
double weight;
int reps;
ExerciseSet({
@required this.index,
this.weight,
this.reps,
});
}
class MainExerciseApp扩展StatefulWidget{
@凌驾
_MainExerciseAppState createState()=>\u MainExerciseAppState();
}
类_mainPerciseAppState扩展状态{
int currentIndex=0;
列表setList=[];
@凌驾
小部件构建(构建上下文){
返回材料PP(
theme:ThemeData.dark().copyWith(scaffoldBackgroundColor:Color.fromARGB(255,18,32,47)),
debugShowCheckedModeBanner:false,
家:脚手架(
正文:中(
子:集合列表(
setList:setList,
removeSet:_removeSet,
),
),
浮动操作按钮:浮动操作按钮(
子:图标(Icons.add),
onPressed:\u addSet
),
),
);
}
void _addSet(){
currentIndex++;
设置状态(){
setList.add(ExerciseSet(
索引:当前索引,
销售代表:0
));
});
}
void _removeSet(ExerciseSet ExerciseSet){
设置状态(){
setList.remove(exerciseSet);
});
}
}
类SetList扩展了StatefulWidget{
最终列表集合列表;
最终功能移除集;
集合列表({
@需要此.setList,
@需要此.removeSet,
});
@凌驾
_SetListState createState()=>\u SetListState();
}
类_SetListState扩展了状态{
@凌驾
小部件构建(构建上下文){
返回ListView.builder(
itemCount:widget.setList.length,
itemBuilder:(上下文,索引){
返回行(
儿童:[
Text(“Set${widget.setList[index].index.toString()}”),
灵活的(
孩子:填充(
填充:常量边集。对称(水平:40),
子项:TextFormField(
initialValue:widget.setList[index].reps.toString(),
装饰:输入装饰(
labelText:“代表计数”,
),
),
),
),
图标按钮(
图标:图标(Icons.delete),
onPressed:()=>widget.removeSet(widget.setList[index]),
),
],
);
}
);
}
}
类练习集{
整数指数;
双倍重量;
杰出代表;
练习集({
@需要这个索引,
这个重量,
这个,代表,,
});
}
有些事情会让你的生活变得更轻松。如果您想进一步了解如何构建这样一个可管理的列表,可以查看这个GitHub 您应该在地图中保存这些文本字段的状态 解决方案
import 'package:flutter/material.dart';
final Color darkBlue = Color.fromARGB(255, 18, 32, 47);
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
theme: ThemeData.dark().copyWith(scaffoldBackgroundColor: darkBlue),
debugShowCheckedModeBanner: false,
home: Scaffold(
body: Center(
child: MyWidget(),
),
),
);
}
}
class MyWidget extends StatelessWidget {
@override
Widget build(BuildContext context) {
return SetBuilderWidget();
}
}
class TempSet {
int weight;
int rep;
int order;
TempSet(this.order, this.weight, this.rep);
}
class SetBuilderWidget extends StatefulWidget {
@override
State<StatefulWidget> createState() => _SetBuilderWidgetState();
}
class _SetBuilderWidgetState extends State<SetBuilderWidget> {
final sets = [];
final List<TempSet> tempSet = [];
Widget _row(int index, int rep) {
TextEditingController _controller =
TextEditingController(text: rep != null ? rep.toString() : "0");
return Row(
children: <Widget>[
Text("Set $index"),
Flexible(
child: Padding(
padding: const EdgeInsets.symmetric(horizontal: 40),
child: TextField(
onChanged: (text) {
tempSet[index].rep = num.parse(text).toInt();
print(tempSet);
},
controller: _controller,
decoration: InputDecoration(
labelText: "Rep count",
),
),
),
),
IconButton(
icon: Icon(Icons.delete),
onPressed: () => _removeSet(index),
),
],
);
}
List<Widget> _rows() {
return tempSet.map((s) => _row(s.order, s.rep)).toList();
}
void _addSet() {
if (tempSet.length == 0) {
tempSet.add(TempSet(0, null, null));
} else {
final lastSet = tempSet.last;
tempSet.add(TempSet(tempSet.indexOf(lastSet) + 1, null, null));
}
}
void _removeSet(int index) {
setState(() {
tempSet.removeAt(index);
_updateIndexes();
});
}
void _updateIndexes() {
tempSet.asMap().forEach((index, s) {
s.order = index;
});
}
@override
void initState() {
_addSet();
super.initState();
}
@override
Widget build(BuildContext context) {
return Column(
children: <Widget>[
..._rows(),
RaisedButton(
onPressed: () {
setState(() {
_addSet();
});
},
child: Text("Add set"),
)
],
);
}
}
导入“包装:颤振/材料.省道”;
最终颜色暗蓝色=颜色。