I want to add text to the list when the onPressedButton is pressed. But I get the following error: RangeError: Invalid value: Not in inclusive range 0..2: 3 flutter

In some related answers, I confirmed that it was because 'itemCount: name.length' was not added, and I added it, but the result was the same. What is the problem?

The coding is as follows.

import 'package:flutter/material.dart';

void main() {
  runApp(const MaterialApp(home: MyApp()));
}

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

  @override
  State<MyApp> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  var total = 3;
  var name = ['김영숙', '홍길동', '피자집'];
  var like = [0, 0, 0];

  addName(a) {
    setState(() {
      name.add(a);
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      floatingActionButton: FloatingActionButton(
        child: Text(total.toString()),
        onPressed: () {
          print(context.findAncestorWidgetOfExactType<MaterialApp>());
          showDialog(
              context: context,
              builder: (context) {
                return DialogUI(addName: addName);
              });
        },
      ),
      appBar: AppBar(
        title: Text(total.toString()),
      ),
      body: ListView.builder(
        itemCount: name.length,
        itemBuilder: (context, i) {
          return ListTile(
            leading: Text(like[i].toString()),
            title: Text(name[i]),
            trailing: TextButton(
              style: TextButton.styleFrom(
                padding: const EdgeInsets.all(16.0),
                primary: Colors.white,
                backgroundColor: Colors.blue,
              ),
              child: Text('좋아요'),
              onPressed: () {
                setState(() {
                  like[i]  ;
                });
              },
            ),
          );
        },
      ),
      bottomNavigationBar: BtmBar(),
    );
  }
}

class DialogUI extends StatelessWidget {
  DialogUI({Key? key, this.addName}) : super(key: key);
  final addName;
  var inputData = TextEditingController();
  var inputData2 = {};

  @override
  Widget build(BuildContext context) {
    return Dialog(
      child: Container(
        padding: EdgeInsets.all(20),
        width: 300,
        height: 300,
        child: Column(
          children: [
            TextField(
              controller: inputData,
            ),
            TextButton(
              child: Text('OK'),
              onPressed: () {
                addName(inputData.text);
              },
            ),
            TextButton(
              child: Text('Cancel'),
              onPressed: () {
                Navigator.pop(context);
              },
            )
          ],
        ),
      ),
    );
  }
}

class BtmBar extends StatelessWidget {
  const BtmBar({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return BottomAppBar(
      child: Row(
        mainAxisAlignment: MainAxisAlignment.spaceEvenly,
        children: [
          Icon(Icons.phone),
          Icon(Icons.message),
          Icon(Icons.access_alarms),
        ],
      ),
    );
  }
}

CodePudding user response：

RangeError comes up when we try to access the member of an array(here list) that doesn't exist. Here, please check while accessing the members of name & like at a particular index do exist.

CodePudding user response：

the problem is that you make name grow but not like

So you need to do

addName(a) {
  setState(() {
    name.add(a);
    like.add(0);
  });
}

so new names also have an entry for likes.

another tip is to just remove total and where you use total.toString() use name.length.toString() instead so that also shows the correct amount at all times