TIF19 Flutter Counter

main.dart

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        debugShowCheckedModeBanner: false, 
        home: const MyHomePage(title: 'Zähler'),
        theme: ThemeData(
          primarySwatch: Colors.orange,
        )
    );
  }
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0; // initialer Zustand
  
  void _incrementCounter() {
    setState(() {
      _counter++;
    });
  }
  
  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(title: Text(widget.title)),
        body: Center(
          child: Column(mainAxisAlignment: MainAxisAlignment.center, children: [
            const Text('So oft wurde der Button gedrückt:'),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.headline2,
            )
          ]),
        ),
        floatingActionButton: FloatingActionButton(
          onPressed: _incrementCounter,
          tooltip: 'Plus 1',
          child: const Icon(Icons.add),
        ));
  }
}

class MyHomePage extends StatefulWidget {
  final String title; // Instanzvariable

  // Konstruktor
  const MyHomePage({
    required this.title,
  });

  @override
  _MyHomePageState createState() => _MyHomePageState();
}