Flutter 颤振两个对象listview.builder向上滚动错误-返回旧的或无效的状态实例

这些是我的项目文件：

主飞镖

import 'package:flutter/material.dart';
import 'package:flutterapp/object1form.dart';
import 'package:flutterapp/object2form.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(
        primarySwatch: Colors.blue,
      ),
      home: AddScreen(),
    );
  }
}

class Object1 {
  String name;
  String count;
  String units;
  Object1({this.name = '', this.count = '', this.units = ''});
}

class Object2 {
  int objectNumber;
  String name;
  Object2(int i){this.objectNumber = i; this.name = '';}
}


class AddScreen extends StatefulWidget {
  @override
  _AddScreenState createState() => _AddScreenState();
}

class _AddScreenState extends State<AddScreen> {
  List<Object1Form> object1List = [];
  List<Object2Form> object2List = [];

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        body: Container(
          child: new Theme(
            data: new ThemeData(
              primaryColorDark: Colors.blue,
            ),
            child: ListView(children: <Widget>[
              //---------------------object1-------------
              SizedBox(height: 20),
              ConstrainedBox(
                constraints: BoxConstraints(maxHeight: 10000, minHeight: 0),
                child: ListView.builder(
                  shrinkWrap: true,
                  physics: ScrollPhysics(),
                  addAutomaticKeepAlives: true,
                  itemBuilder: (_, i) {
                    if (i == object1List.length) {
                      return Align(
                        alignment: Alignment.center,
                        child: RaisedButton.icon(
                          icon: Icon(
                            Icons.add,
                          ),
                          textColor: Colors.white,
                          color: Colors.blue,
                          label: Text("Add object1"),
                          onPressed: onAddObject1,
                          shape: new RoundedRectangleBorder(
                            borderRadius: new BorderRadius.circular(30.0),
                          ),
                        ),
                      );
                    }
                    return object1List[i];
                  },
                  itemCount: object1List.length + 1,
                ),
              ),
              //-----------------object2----------------------
              SizedBox(height: 20),
              ConstrainedBox(
                constraints: BoxConstraints(maxHeight: 10000, minHeight: 0),
                child: ListView.builder(
                  shrinkWrap: true,
                  physics: ScrollPhysics(),
                  addAutomaticKeepAlives: true,
                  itemBuilder: (_, i) {
                    if (i == object2List.length) {
                      return Align(
                        alignment: Alignment.center,
                        child: RaisedButton.icon(
                          icon: Icon(
                            Icons.add,
                          ),
                          textColor: Colors.white,
                          color: Colors.blue,
                          label: Text("Add object2"),
                          onPressed: (){onAddObject2(object2List.length+1);},
                          shape: new RoundedRectangleBorder(
                            borderRadius: new BorderRadius.circular(30.0),
                          ),
                        ),
                      );
                    }
                    return object2List[i];
                  },
                  itemCount: object2List.length + 1,
                ),
              ),
              //--------------------------------------------------
            ]),
          ),
        ));
  }

  ///on form user deleted
  void onDeleteObject1(Object1 _object1) {
    setState(() {
      var find = object1List.firstWhere(
            (it) => it.object1 == _object1,
        orElse: () => null,
      );
      if (find != null) object1List.removeAt(object1List.indexOf(find));
    });
  }

  ///on add form
  void onAddObject1() {
    setState(() {
      var _object1 = Object1();
      object1List.add(Object1Form(
        key: GlobalKey<FormState>(),
        object1: _object1,
        onDelete: () => onDeleteObject1(_object1),
      ));
    });
  }

  ///on form user deleted
  void onDeleteObject2(Object2 _object2) {
    setState(() {
      var find = object2List.firstWhere(
            (it) => it.object2 == _object2,
        orElse: () => null,
      );
      if (find != null) object2List.removeAt(object2List.indexOf(find));
      for(int j = 0; j< object2List.length; j++){
        object2List[j].object2.objectNumber=j+1;
      }
    });
  }

  ///on add form
  void onAddObject2(int i) {
    setState(() {
      var _object2 = Object2(i);
      object2List.add(Object2Form(
        key: GlobalKey<FormState>(),
        object2: _object2,
        onDeleteObject2: () => onDeleteObject2(_object2),
      ));
    });
  }
}

导入“包装：颤振/材料.省道”；
导入“包：app/object1form.dart”；
导入“包：app/object2form.dart”；
void main（）=>runApp（MyApp（））；
类MyApp扩展了无状态小部件{
//此小部件是应用程序的根。
@凌驾
小部件构建（构建上下文）{
返回材料PP(
标题：“颤振演示”，
主题：主题数据(
主样本：颜色。蓝色，
),
主页：AddScreen（），
);
}
}
类对象1{
字符串名；
字符串计数；
弦单位；
Object1（{this.name=''，this.count=''，this.units=''}）；
}
类对象2{
int objectNumber；
字符串名；
Object2（int i）{this.objectNumber=i；this.name=''；}
}
类AddScreen扩展StatefulWidget{
@凌驾
_AddScreenState createState（）=>\u AddScreenState（）；
}
类_AddScreenState扩展状态

导致错误的相关小部件是：
列表视图file:///C:/Users/itay1/AndroidStudioProjects/flutter_app/lib/main.dart:57:33
引发异常时，这是堆栈：

2个新的StatefulElement（包：flatter/src/widgets/framework.dart:4324:7）
3 StatefulWidget.createElement（包：flatter/src/widgets/framework.dart:809:38）
4 Element.inflateWidget（包：flatter/src/widgets/framework.dart:3189:40）
5 Element.updateChild（包：flatter/src/widgets/framework.dart:2988:12）
6 SingleChildRenderObjectElement.mount（包：flatter/src/widgets/framework.dart:5445:14）
。。。
════════════════════════════════════════════════════════════════════════════════════════════════════

════════ （2） widgets库捕获到异常═══════════════════════════════════════════════════
“package:flatter/src/rendering/sliver_multi_box_adapter.dart”：失败的断言：第263行第16位：“child==null | | | indexOf（child）>index”：不正确。
导致错误的相关小部件是：
列表视图file:///C:/Users/itay1/AndroidStudioProjects/flutter_app/lib/main.dart:57:33
════════════════════════════════════════════════════════════════════════════════════════════════════

════════ （3） widgets库捕获到异常═══════════════════════════════════════════════════
“package:flatter/src/rendering/sliver_multi_box_adapter.dart”：失败的断言：第263行第16位：“child==null | | | indexOf（child）>index”：不正确。
导致错误的相关小部件是：
列表视图file:///C:/Users/itay1/AndroidStudioProjects/flutter_app/lib/main.dart:57:33
════════════════════════════════════════════════════════════════════════════════════════════════════

════════ （4） widgets库捕获到异常═══════════════════════════════════════════════════
“package:flatter/src/rendering/sliver_multi_box_adapter.dart”：失败的断言：第263行第16位：“child==null | | | indexOf（child）>index”：不正确。
导致错误的相关小部件是：
列表视图file:///C:/Users/itay1/AndroidStudioProjects/flutter_app/lib/main.dart:57:33
════════════════════════════════════════════════════════════════════════════════════════════════════

════════ （5） 呈现库捕获到异常═════════════════════════════════════════════════
“package:flatter/src/widgets/framework.dart”：失败的断言：第2416行位置20:“\u debugCurrentBuildTarget==context”：不正确。
导致错误的相关小部件是：
列表视图file:///C:/Users/itay1/AndroidStudioProjects/flutter_app/lib/main.dart:57:33
════════════════════════════════════════════════════════════════════════════════════════════════════

════════ （6） 呈现库捕获到异常═════════════════════════════════════════════════
对null调用了getter“scrollOffsetCorrection”。
收件人：空
尝试呼叫：scrollOffsetCorrection
导致错误的相关小部件是：
列表视图file:///C:/Users/itay1/AndroidStudioProjects/flutter_app/lib/main.dart:57:33
════════════════════════════════════════════════════════════════════════════════════════════════════

════════ （7） 呈现库捕获到异常════════════════════════
import 'package:flutter/material.dart';
import 'package:flutterapp/main.dart';

typedef OnDelete();

class Object1Form extends StatefulWidget {
  final Object1 object1;
  final OnDelete onDelete;
  final state = new _Object1FormState();
  Object1Form({Key key, this.object1, this.onDelete}) : super(key: key);

  @override
  _Object1FormState createState() => state;
  bool isValid() => state.validate();
}

class _Object1FormState extends State<Object1Form> {
  final _formKey = GlobalKey<FormState>();
  List<String> _units = <String>['', 'red', 'green', 'blue', 'orange'];
  String _unit = '';

  @override
  Widget build(BuildContext context) {
    final halfMediaWidth = MediaQuery.of(context).size.width;
    return Padding(
        padding: EdgeInsets.all(16),
        child: Material(
          elevation: 1,
          clipBehavior: Clip.antiAlias,
          borderRadius: new BorderRadius.circular(30.0),
          color: Colors.white70,
          child: new Theme(
              data: new ThemeData(
                primaryColorDark: Colors.blue,
              ),
              child: Form(
                  key: _formKey,
                  child: Column(mainAxisSize: MainAxisSize.min, children: <Widget>[
                    Column(children: <Widget>[
                      Container(
                        alignment: Alignment.topCenter,
                        child: Row(
                            crossAxisAlignment: CrossAxisAlignment.start,
                            children: <Widget>[
                              Container(
                                width: halfMediaWidth * 0.8,
                                child: Padding(
                                  padding: EdgeInsets.only(
                                      left: 16, right: 16, top: 10, bottom: 10),
                                  child: TextFormField(
                                    onSaved: (val) => widget.object1.name = val,
                                    validator: (val) => val.length > 3
                                        ? null
                                        : 'invalid',
                                    decoration: InputDecoration(
                                      labelText: 'Name',
                                      hintText: 'Enter Name',
                                      fillColor: Colors.white,
                                      border: new OutlineInputBorder(
                                        borderRadius:
                                        new BorderRadius.circular(30.0),
                                        borderSide:
                                        new BorderSide(color: Colors.blue),
                                      ),
                                      isDense: true,
                                    ),
                                  ),
                                ),
                              ),
                              Container(
                                width: halfMediaWidth * 0.1,
                                child: IconButton(
                                  icon: Icon(Icons.delete),
                                  onPressed: widget.onDelete,
                                ),
                              ),
                            ]),
                      ),
                    ]),
                    Column(children: <Widget>[
                      Container(
                        alignment: Alignment.topCenter,
                        child: Row(
                          crossAxisAlignment: CrossAxisAlignment.start,
                          children: <Widget>[
                            Container(
                                width: halfMediaWidth * 0.3,
                                child: Padding(
                                  padding: EdgeInsets.only(
                                      left: 16, right: 5, bottom: 10),
                                  child: TextFormField(
                                    onSaved: (val) =>
                                    widget.object1.count = val,
                                    validator: (input) {
                                      final isDigitsOnly = int.tryParse(input);
                                      return isDigitsOnly == null
                                          ? 'Input needs to be digits only'
                                          : null;
                                    },
                                    decoration: InputDecoration(
                                      labelText: 'Count',
                                      hintText: 'Enter Count',
                                      fillColor: Colors.white,
                                      border: new OutlineInputBorder(
                                        borderRadius:
                                        new BorderRadius.circular(30.0),
                                        borderSide:
                                        new BorderSide(color: Colors.blue),
                                      ),
                                    ),
                                  ),
                                )),
                            Container(
                                width: halfMediaWidth * 0.6,
                                child: Padding(
                                  padding: EdgeInsets.only(left: 5, right: 2),
                                  child: new FormField(
                                    builder: (FormFieldState state) {
                                      return InputDecorator(
                                        decoration: InputDecoration(
                                          labelText: 'Unit',
                                          fillColor: Colors.white,
                                          border: new OutlineInputBorder(
                                            borderRadius:
                                            new BorderRadius.circular(30.0),
                                            borderSide: new BorderSide(
                                                color: Colors.blue),
                                          ),
                                          isDense: true,
                                        ),
                                        isEmpty: _unit == '',
                                        child: new DropdownButtonHideUnderline(
                                          child: new DropdownButton(
                                            value: _unit,
                                            isDense: true,
                                            onChanged: (String newValue) {
                                              setState(() {
                                                widget.object1.units = newValue;
                                                _unit = newValue;
                                                state.didChange(newValue);
                                              });
                                            },
                                            items: _units.map((String value) {
                                              return new DropdownMenuItem(
                                                value: value,
                                                child: new Text(value),
                                              );
                                            }).toList(),
                                          ),
                                        ),
                                      );
                                    },
                                  ),
                                )),
                          ],
                        ),
                      ),
                    ]),
                  ]))),
        ));
  }

  ///form validator
  bool validate() {
    var valid = _formKey.currentState.validate();
    if (valid) _formKey.currentState.save();
    return valid;
  }
}

import 'package:flutter/material.dart';
import 'package:flutterapp/main.dart';

typedef OnDeleteObject2();

class Object2Form extends StatefulWidget {
  final Object2 object2;
  final OnDeleteObject2 onDeleteObject2;
  final state = new _Object2FormState();
  Object2Form({Key key, this.object2, this.onDeleteObject2}) : super(key: key);

  @override
  _Object2FormState createState() => state;
  bool isValid2() => state.validateObject2();
}

class _Object2FormState extends State<Object2Form> {
  final _form2 = GlobalKey<FormState>();
  @override
  Widget build(BuildContext context) {
    final halfMediaWidth = MediaQuery.of(context).size.width;
    int objectNumber = widget.object2.objectNumber;
    return Padding(
        padding: EdgeInsets.all(16),
        child: Material(
          elevation: 1,
          clipBehavior: Clip.antiAlias,
          borderRadius: new BorderRadius.circular(30.0),
          color: Colors.white70,
          child: new Theme(
              data: new ThemeData(
                primaryColorDark: Colors.blue,
              ),
              child: Form(
                  key: _form2,
                  child:
                  Column(mainAxisSize: MainAxisSize.min, children: <Widget>[
                    Column(children: <Widget>[
                      Container(
                        alignment: Alignment.topCenter,
                        child: Row(
                            crossAxisAlignment: CrossAxisAlignment.start,
                            children: <Widget>[
                              Container(
                                width: halfMediaWidth * 0.8,
                                child: Padding(
                                  padding: EdgeInsets.only(
                                      left: 16, right: 16, top: 10, bottom: 10),
                                  child: TextFormField(
                                    onSaved: (val) => widget.object2.name = val,
                                    validator: (val) => val.length > 3
                                        ? null
                                        : 'invalid',
                                    decoration: InputDecoration(
                                      labelText: 'name',
                                      hintText: 'Enter name',
                                      fillColor: Colors.white,
                                      border: new OutlineInputBorder(
                                        borderRadius:
                                        new BorderRadius.circular(30.0),
                                        borderSide:
                                        new BorderSide(color: Colors.blue),
                                      ),
                                      isDense: true,
                                    ),
                                    keyboardType: TextInputType.multiline,
                                    maxLines: 10,
                                  ),
                                ),
                              ),
                              Column(children: <Widget>[
                                Container(
                                  width: halfMediaWidth * 0.1,
                                  child: IconButton(
                                    icon: Icon(Icons.delete),
                                    onPressed: widget.onDeleteObject2,
                                  ),
                                ),
                                Column(
                                  mainAxisAlignment: MainAxisAlignment.center,
                                  crossAxisAlignment: CrossAxisAlignment.center,
                                  children: <Widget>[
                                    Container(
                                      width: 30,
                                      height: 30,
                                      child: Center(
                                        child:
                                        Text('$objectNumber', style:TextStyle(fontWeight: FontWeight.bold,fontSize: 20)),),
                                      decoration: BoxDecoration(
                                        borderRadius: BorderRadius.all(
                                          Radius.circular(200),
                                        ),
                                        color: Colors.blue,
                                      ),
                                    )
                                  ],
                                ),
                              ])
                            ]),
                      ),
                    ]),
                  ]))),
        ));
  }

  ///form validator
  bool validateObject2() {
    var valid = _form2.currentState.validate();
    if (valid) _form2.currentState.save();
    return valid;
  }
}