Flutter计数器应用 #

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: 'Counter App',
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.blue),
        useMaterial3: true,
      ),
      home: const CounterPage(),
    );
  }
}

class CounterPage extends StatefulWidget {
  const CounterPage({super.key});

  @override
  State<CounterPage> createState() => _CounterPageState();
}

class _CounterPageState extends State<CounterPage> {
  int _counter = 0;

  void _increment() {
    setState(() {
      _counter++;
    });
  }

  void _decrement() {
    setState(() {
      _counter--;
    });
  }

  void _reset() {
    setState(() {
      _counter = 0;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Counter App'),
        centerTitle: true,
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            const Text(
              'Count:',
              style: TextStyle(fontSize: 24),
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.displayLarge,
            ),
          ],
        ),
      ),
      floatingActionButton: Column(
        mainAxisAlignment: MainAxisAlignment.end,
        children: [
          FloatingActionButton(
            heroTag: 'increment',
            onPressed: _increment,
            child: const Icon(Icons.add),
          ),
          const SizedBox(height: 10),
          FloatingActionButton(
            heroTag: 'decrement',
            onPressed: _decrement,
            child: const Icon(Icons.remove),
          ),
          const SizedBox(height: 10),
          FloatingActionButton(
            heroTag: 'reset',
            onPressed: _reset,
            child: const Icon(Icons.refresh),
          ),
        ],
      ),
    );
  }
}