0

我遇到了这个异常，我确实搜索了stackoverflow，但我不明白如何处理这个问题，我只是开始玩代码并试图理解并尝试解决。如果有人帮助我，这将对我有所帮助，谢谢你提前。

======== Exception caught by widgets library =======================================================
The following RangeError was thrown building CardWithTextformfield(dirty, state: _CardWithTextformfieldState#a698e):
RangeError (index): Invalid value: Only valid value is 0: 1

The relevant error-causing widget was: 
  CardWithTextformfield file:///E:/flutter%20apps/flutter%20apps/cardview_textformfield/lib/main.dart:11:13
When the exception was thrown, this was the stack: 
#0      List.[] (dart:core-patch/growable_array.dart:254:60)
#1      _CardWithTextformfieldState.cardslist (package:cardview_textformfield/main.dart:134:35)
#2      _CardWithTextformfieldState.build (package:cardview_textformfield/main.dart:107:60)
#3      StatefulElement.build (package:flutter/src/widgets/framework.dart:4691:27)
#4      ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4574:15)

并且红屏出现几秒钟然后正常，我尝试生成最多4张卡片并且第一张卡片可见性是真实的，因为我希望第一张卡片在屏幕出现后立即可见并且剩余的卡片将可见我点击floatingActionButton。下面是我的完整代码。

import 'package:flutter/material.dart';

    void main() {
      runApp(App());
    }
    
    class App extends StatelessWidget {
      @override
      Widget build(BuildContext context) {
        return MaterialApp(
          home: CardWithTextformfield(),
        );
      }
    }
    
    class CardWithTextformfield extends StatefulWidget {
      const CardWithTextformfield({Key? key}) : super(key: key);
    
      @override
      _CardWithTextformfieldState createState() => _CardWithTextformfieldState();
    }
    
    class _CardWithTextformfieldState extends State<CardWithTextformfield>  {
    
    
      var name =<TextEditingController>[];
      var id =<TextEditingController>[];
      
    
      var addCard =2;
      bool cardOneVisibility=true;
      bool cardTwoVisibility=false;
      bool cardThreeVisibility=false;
      bool cardFourVisibility=false;
    
    
      void incrementcard(){
        setState(() {
          
          if(addCard==1){
            cardOneVisibility=true;
          }
          else if(addCard==2){
            cardOneVisibility=true;
            cardTwoVisibility=true;
          }
          else if(addCard==3){
            cardOneVisibility=true;
            cardTwoVisibility=true;
            cardThreeVisibility=true;
          }
          else if(addCard==4){
            cardOneVisibility=true;
            cardTwoVisibility=true;
            cardThreeVisibility=true;
            cardFourVisibility=true;
          }
          addCard++;
    
        });
      }
    
      @override
      Widget build(BuildContext context) {
        return Scaffold(
          appBar: AppBar(
            title: Text('Card with TextformField'),
          ),
          floatingActionButton: FloatingActionButton(
            onPressed: addCard>=5 ? null : incrementcard,
            child: Icon(Icons.add),
          ),
          body: Container(
    
            child:SingleChildScrollView(
              child: Column(
                children: [
                  Visibility(visible: cardOneVisibility,child: cardslist(1)),
                  Visibility(visible: cardTwoVisibility,child: cardslist(2)),
                  Visibility(visible: cardThreeVisibility,child: cardslist(3)),
                  Visibility(visible: cardFourVisibility,child: cardslist(4)),
                ],
              ),
            ),
          ),
        );
      }
      Widget cardslist(int index){
        if(name.length <= index){
          name.add(TextEditingController());
          id.add(TextEditingController());
        }
        return Card(
          margin: EdgeInsets.all(10),
          child: Container(
            child: Column(
              children: [
                Row(
                  mainAxisAlignment: MainAxisAlignment.spaceBetween,
                  children: [
                    Container(
                        margin: EdgeInsets.all(10),
                        child: Text('Team Name: ')),
                    Expanded(child: TextFormField(
                      controller: name[index],
                        decoration: InputDecoration(hintText: 'Team Name'),
                    ),),
                    Container(
                      margin: EdgeInsets.all(10),
                      child: Text('Team Id: '),),
                    Expanded(child: TextFormField(
                      controller: id[index],
                        decoration: InputDecoration(hintText: 'Team Id'),
                    ),),
                  ],
                ),
                Row(
                  mainAxisAlignment: MainAxisAlignment.spaceBetween,
                  children: [
                    GestureDetector(
                      child: Container(
                        width: 50,height: 50,
                        margin: EdgeInsets.all(10),
                        decoration: BoxDecoration(
                          shape: BoxShape.rectangle,
                          color:Colors.grey,
                        ),
                        child: Center(child: Text('IT'),),
                      ),

                    ),
                    GestureDetector(
                      child: Container(
                        width: 50,height: 50,
                        margin: EdgeInsets.all(10),
                        decoration: BoxDecoration(
                          shape: BoxShape.rectangle,
                          color: Colors.grey,
                        ),
                        child: Center(child: Text('DEV'),),
                      ),
                    ),
                    GestureDetector(
                      child: Container(
                        width: 50,height: 50,
                        margin: EdgeInsets.all(10),
                        decoration: BoxDecoration(
                          shape: BoxShape.rectangle,
                          color: Colors.grey,
                        ),
                        child: Center(child: Text('TEST'),),
                      ),
                    ),
                    GestureDetector(
                      child: Container(
                        width: 50,height: 50,
                        margin: EdgeInsets.all(10),
                        decoration: BoxDecoration(
                          shape: BoxShape.rectangle,
                          color: Colors.grey,
                        ),
                        child: Center(child: Text('HR'),),
                      ),
                    ),
                  ],
                )
              ],
            ),
          ),
        );
      }
    }
4

2 回答 2

2

索引从 0 开始，而不是 1，需要在您的不同位置进行更改。我为您更新了代码，请检查一下。

import 'package:flutter/material.dart';

void main() {
  runApp(App());
}

class App extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: CardWithTextformfield(),
    );
  }
}

class CardWithTextformfield extends StatefulWidget {
  const CardWithTextformfield({Key key}) : super(key: key);

  @override
  _CardWithTextformfieldState createState() => _CardWithTextformfieldState();
}

class _CardWithTextformfieldState extends State<CardWithTextformfield>  {


  var name =<TextEditingController>[];
  var id =<TextEditingController>[];


  var addCard =0;
  bool cardOneVisibility=true;
  bool cardTwoVisibility=false;
  bool cardThreeVisibility=false;
  bool cardFourVisibility=false;


  void incrementcard(){
    setState(() {

      if(addCard==0){
        cardOneVisibility=true;
      }
      else if(addCard==1){
        cardOneVisibility=true;
        cardTwoVisibility=true;
      }
      else if(addCard==2){
        cardOneVisibility=true;
        cardTwoVisibility=true;
        cardThreeVisibility=true;
      }
      else if(addCard==3){
        cardOneVisibility=true;
        cardTwoVisibility=true;
        cardThreeVisibility=true;
        cardFourVisibility=true;
      }
      addCard++;

    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Card with TextformField'),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: addCard>=4 ? null : incrementcard,
        child: Icon(Icons.add),
      ),
      body: Container(

        child:SingleChildScrollView(
          child: Column(
            children: [
              Visibility(visible: cardOneVisibility,child: cardslist(0)),
              Visibility(visible: cardTwoVisibility,child: cardslist(1)),
              Visibility(visible: cardThreeVisibility,child: cardslist(2)),
              Visibility(visible: cardFourVisibility,child: cardslist(3)),
            ],
          ),
        ),
      ),
    );
  }
  Widget cardslist(int index){
    if(name.length <= index){
      name.add(TextEditingController());
      id.add(TextEditingController());
    }
    return Card(
      margin: EdgeInsets.all(10),
      child: Container(
        child: Column(
          children: [
            Row(
              mainAxisAlignment: MainAxisAlignment.spaceBetween,
              children: [
                Container(
                    margin: EdgeInsets.all(10),
                    child: Text('Team Name: ')),
                Expanded(child: TextFormField(
                  controller: name[index],
                  decoration: InputDecoration(hintText: 'Team Name'),
                ),),
                Container(
                  margin: EdgeInsets.all(10),
                  child: Text('Team Id: '),),
                Expanded(child: TextFormField(
                  controller: id[index],
                  decoration: InputDecoration(hintText: 'Team Id'),
                ),),
              ],
            ),
            Row(
              mainAxisAlignment: MainAxisAlignment.spaceBetween,
              children: [
                GestureDetector(
                  child: Container(
                    width: 50,height: 50,
                    margin: EdgeInsets.all(10),
                    decoration: BoxDecoration(
                      shape: BoxShape.rectangle,
                      color:Colors.grey,
                    ),
                    child: Center(child: Text('IT'),),
                  ),

                ),
                GestureDetector(
                  child: Container(
                    width: 50,height: 50,
                    margin: EdgeInsets.all(10),
                    decoration: BoxDecoration(
                      shape: BoxShape.rectangle,
                      color: Colors.grey,
                    ),
                    child: Center(child: Text('DEV'),),
                  ),
                ),
                GestureDetector(
                  child: Container(
                    width: 50,height: 50,
                    margin: EdgeInsets.all(10),
                    decoration: BoxDecoration(
                      shape: BoxShape.rectangle,
                      color: Colors.grey,
                    ),
                    child: Center(child: Text('TEST'),),
                  ),
                ),
                GestureDetector(
                  child: Container(
                    width: 50,height: 50,
                    margin: EdgeInsets.all(10),
                    decoration: BoxDecoration(
                      shape: BoxShape.rectangle,
                      color: Colors.grey,
                    ),
                    child: Center(child: Text('HR'),),
                  ),
                ),
              ],
            )
          ],
        ),
      ),
    );
  }
}

输出：

在此处输入图像描述

于 2021-08-31T13:00:08.647 回答
0

卡片 1 使用id和name数组的第一个元素。数组第一个元素的索引为 0。

在cardslist功能上，

更改name[index]为name[index - 1]

更改id[index]为id[index - 1]

于 2021-08-31T13:00:49.390 回答