Ivon

class TestWidget extends StatefulWidget{
  @override
  State<StatefulWidget> createState() => TestState();
}

class TestState extends State<TestWidget> {
  String _text;
  @override
  Widget build(BuildContext context) {
    if (_text == null)
      _text = "Empty";
    return Text(_text);
  }

  void updateText(String newText) {
    setState(() {
      this._text = newText;
    });
  }
}