Flutter TextFormField: The keyboard appeared and instantly disappeared

Question

When I click the TextFormField, the keyboard appears, then it disappears instantly, just like blinking. I wonder that whether it is because the lacking of some parameters? Or some other problems? Thanks. Here are my relative codes.

final _formKey = GlobalKey<FormState>();
String? _account;
Widget _showAccountInput() {
    return Padding(
      padding: const EdgeInsets.fromLTRB(15.0, 10.0, 0.0, 0.0),
      child: new TextFormField(
        maxLines: 1,
        obscureText: true,
        autofocus: false,
        style: TextStyle(fontSize: 15),
        decoration: new InputDecoration(
            border: InputBorder.none,
            hintText: 'input',
            icon: new Icon(
              Icons.lock,
              color: Colors.grey,
            )),
        onSaved: (value) => _account = value?.trim(),
      ),
    );
  }
  Widget build(BuildContext context) {
    // TODO: implement build
    return Scaffold(
      appBar: new AppBar(
        title: new Text("Second Screen"),
      ),
      body: Form(
        key: _formKey,
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: <Widget>[
            _showAccountInput()


          ],
        ),
      ),
    );
  }
}

Answer 1

如果您的构建方法在StatelessWidget<\/strong>中，请尝试将其更改为StatefulWidget<\/strong>

"

Answer 2

I've modified a bit of your code, and the keyboard is working fine. Maybe you can give it a try or compare with your code so you find the cause. Here is the full code

import 'package:flutter/material.dart';

void main() {
  runApp(const MyApp());
}

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: const MyHomePage(),
    );
  }
}

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

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  final _formKey = GlobalKey<FormState>();
  String? _account;
  Widget _showAccountInput() {
    return Padding(
      padding: const EdgeInsets.fromLTRB(15.0, 10.0, 0.0, 0.0),
      child: TextFormField(
        maxLines: 1,
        obscureText: true,
        autofocus: false,
        style: const TextStyle(fontSize: 15),
        decoration: const InputDecoration(
            border: InputBorder.none,
            hintText: 'input',
            icon: Icon(
              Icons.lock,
              color: Colors.grey,
            )),
        onSaved: (value) => _account = value?.trim(),
      ),
    );
  }

  // @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text("Second Screen"),
      ),
      body: Form(
        key: _formKey,
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: <Widget>[_showAccountInput()],
        ),
      ),
    );
  }
}

Answer 3

1. no need to use statefull widget because the state of widget is not changing.<\/li>
2. <\/li><\/ol>

    class Test extends StatelessWidget { @override Widget build(BuildContext context) { return Scaffold( body: Column( crossAxisAlignment: CrossAxisAlignment.center, mainAxisAlignment: MainAxisAlignment.center, children: [ShowAccountInput()], ), ); } } class ShowAccountInput extends StatelessWidget { String? account; ShowAccountInput({ this.account, Key? key, }) : super(key: key); @override Widget build(BuildContext context) { return Padding( padding: const EdgeInsets.fromLTRB(15.0, 10.0, 0.0, 0.0), child: TextFormField( maxLines: 1, obscureText: true, decoration: const InputDecoration( hintText: 'input', border: InputBorder.none, icon: Icon( Icons.lock, color: Colors.grey, )), onSaved: (value) => account = value?.trim(), ), ); } }<\/code><\/pre>"