StatefulWidget simple Example

 import "package:flutter/material.dart";

void main() {
  runApp(
    const MaterialApp(
      debugShowCheckedModeBanner: false,
      title: "Simple Form",
      home: SimpleForm(),
    ),
  );
}

class SimpleForm extends StatefulWidget {
  const SimpleForm({super.key});
  @override
  State<StatefulWidget> createState() {
    return SimpleFormState();
  }
}

class SimpleFormState extends State<SimpleForm> {
  String name = "";

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text("Simple Form"),
      ),
      body: Container(
        margin: const EdgeInsets.all(30.0),
        child: Column(
          children: <Widget>[
            TextField(
              onSubmitted: (String userName) {
                setState(() {
                  name = userName;
                });
              },
            ),
            const Padding(
              padding: EdgeInsets.all(20.0),
            ),
            Text(
              "My Name is $name",
              style: const TextStyle(
                fontSize: 25.0,
              ),
            ),
          ],
        ),
      ),
    );
  }
}