I made following simple class to allow entering a string:

import 'package:flutter/material.dart';

class MyDialog {
  late TextEditingController _controller;

  Future<String> showMyDialog(BuildContext context) async {
    _controller = TextEditingController();

    final result = await showDialog(
      context: context,
      builder: (BuildContext context) => _buildMyDialog(context),
    );

    _controller.dispose();
    return result;
  }

  Widget _buildMyDialog(BuildContext context) {
    return AlertDialog(
      title: const Text('Enter string: '),
      content: TextField(
        autofocus: true,
        controller: _controller,
      ),
      actions: [
        TextButton(
          onPressed: () {
            Navigator.of(context).pop(_controller.text);
          },
          child: const Text('OK'),
        ),
      ],
    );
  }
}

and I call it like this:

final dialog = MyDialog();
final result = await dialog.showMyDialog(context);

Unfortunately I get following error:

A TextEditingController was used after being disposed.

Why does it happen and how to fix it? I don't use the controller anywhere after disposing it after all.

CodePudding user response：

On showMyDialog it is getting new TextEditingController every time, we can comment _controller.dispose();. Also, it is possible to get null on this method, therefore it will be better using

Future<String?> showMyDialog(...){...}

Another thing we can do making it nullable

class MyDialog {
  TextEditingController? _controller;

  Future<String?> showMyDialog(BuildContext context) async {
    _controller = TextEditingController();

    final String? result = await showDialog(
      context: context,
      builder: (BuildContext context) => _buildMyDialog(context),
    );
    _controller = null;
    return result;
  }
//....

You can check about _dependents.isEmpty': is not true