import 'dart:math'; import 'package:flutter/material.dart'; void main() { runApp(const MyApp()); } class MyApp extends StatelessWidget { const MyApp({super.key}); @override Widget build(BuildContext context) { return MaterialApp( title: 'Flutter Demo', theme: ThemeData( colorScheme: ColorScheme.fromSeed(seedColor: Colors.black), useMaterial3: true, ), home: const MyHomePage(title: 'Flutter rocks!'), ); } } class MyHomePage extends StatefulWidget { const MyHomePage({super.key, required this.title}); final String title; @override State createState() => _MyHomePageState(); } class _MyHomePageState extends State { int _counter = 0; Color _color = Colors.green; void _incrementCounter() { setState(() { _counter++; _color = Color((Random().nextDouble() * 0xFFFFFF).toInt()).withOpacity(1.0); }); } @override Widget build(BuildContext context) { return Scaffold( appBar: AppBar( backgroundColor: _color, title: Text(widget.title), ), body: Center( child: Column( mainAxisAlignment: MainAxisAlignment.center, children: [ const Text( 'You have pushed the button this many times:', ), Text( '$_counter', style: Theme.of(context).textTheme.headlineMedium, ), if (_counter > 10) Text( 'Why are you clicking?', style: Theme.of(context).textTheme.headlineMedium, ), ], ), ), floatingActionButton: FloatingActionButton( onPressed: _incrementCounter, backgroundColor: _color, tooltip: 'Increment', child: const Icon(Icons.add), ), ); } }