Hello Flutter 06

main.dart

import 'package:flutter/material.dart';

class MyHelloWorld extends StatefulWidget {
  const MyHelloWorld({Key? key}) : super(key: key);
  @override
  MyHelloWorldState createState() => MyHelloWorldState();
}

class MyHelloWorldState extends State<MyHelloWorld> {
  String message = "Hello World";
  
  @override
  build (BuildContext context) {
    return Center(
      child: Column(
        mainAxisSize: MainAxisSize.min,
        children: [
          Text(message),
          TextButton(
            onPressed: () {
              setState(() {
                if ( message == "Hello World" ) {
                  message = "Goodbye!";
                } else {
                  message = "Hello World";
                }
              });
            },
            child: Text("Click me")
          )
        ]
      )
    );
  }
}

void main() {
  runApp(
   MaterialApp(
    title: 'Hello From Flutter', // used by the OS task switcher
    home: SafeArea(
      child:  Scaffold(
        body: MyHelloWorld()
      ),
    ),
  ));
}