TextField will be cleared when the soft keyboard disappears

[shingohu]

1.input text
2.close the softkeyboard，the text will be cleared

Every time the build call,the _oldPWControll print as a new instance

class Demo extends HookWidget {
  final _oldPWControll = TextEditingController();

  final _oldPWFN = FocusNode();
  @override
  Widget build(BuildContext context) {
    print(_oldPWControll);
    return Scaffold(
      resizeToAvoidBottomInset: true,
      body: TextField(
        controller: _oldPWControll,
        textInputAction: TextInputAction.next,
        focusNode: _oldPWFN,
        decoration: InputDecoration(
          hintText: "请输入",
          contentPadding: EdgeInsets.fromLTRB(35.0, 12.0, 12.0, 12.0),
        ),
      ),
    );
  }
}

When Demo as the home Widget of MaterialApp,it is work
but push to the Demo,problems will arise

[rrousselGit]

You should not create these as fields of the class.

Instead create them using hooks inside the build method

Widget build(BuildContext context) {
  final controller = useMemoized(() => TextEditingController());
  ... 
}

[shingohu]

you mean I can't define any final variables directly from KookWidget?

[rrousselGit]

Nor can you do so with any other kind of widgets.

Widgets are immutable. You need a State subclass using hooks to preserve values between builds.