import 'package:flutter/material.dart';

void main() {
  runApp(
    MaterialApp(
      home: MyWidget(),
    ),
  );
}

class MyWidget extends StatefulWidget {
  const MyWidget({Key? key}) : super(key: key);

  @override
  State<MyWidget> createState() => _MyWidgetState();
}

class _MyWidgetState extends State<MyWidget> {
  bool isVisible = true;
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Visibility(
              visible: isVisible,
              child: const Text('暴れるボーイです。\n育児は大変ですね'),
            ),
            TextButton(
              onPressed: () => setState(() => isVisible = !isVisible),
              child: const Text('表示変更'),
            ),
          ],
        ),
      ),
    );
  }
}