widget usage with parameter

headernamewidget.dart

class HeaderNameWidget extends StatefulWidget {
  HeaderNameWidget({Key key, this.name}) : super(key: key);

  final String name;

  @override
  _HeaderNameState createState() => new _HeaderNameState();
}

class _HeaderNameState extends State<HeaderNameWidget> {

  @override
  Widget build(BuildContext context) {
    return new Expanded(
        child: new Center(
            child: new RichText(
      text: new TextSpan(
        // Note: Styles for TextSpans must be explicitly defined.
        // Child text spans will inherit styles from parent
        style: new TextStyle(
          fontSize: 22.0,
          color: Colors.black,
        ),
        children: <TextSpan>[
          new TextSpan(
              text: widget.name,
              style: new TextStyle(fontWeight: FontWeight.bold)),
        ],
      ),
    )));
  }
}

new HeaderNameWidget(name: "Ahmet");