gistfile1.txt

// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

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

class MyHomePage extends StatefulWidget {
  final String title;

  const MyHomePage({
    Key? key,
    required this.title,
  }) : super(key: key);

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  void _incrementCounter(int value) {
    setState(() {
      _counter = value;
    });
  }
  
  void _isEven() {
    final isEven = _counter % 2 == 0 ? "Evennnn" : "that's odddd";
    print(isEven);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: CounterDisplay(count: _counter, onIncrement: _incrementCounter),
      floatingActionButton: FloatingActionButton(
        onPressed: _isEven,
        tooltip: 'Increment',
        child: const Icon(Icons.add),
      ),
    );
  }
}

class CounterDisplay extends StatelessWidget {
  const CounterDisplay({required this.count, required this.onIncrement});
    final int count;
  final  ValueSetter<int> onIncrement;
  @override
  Widget build(BuildContext context) {
    return Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            const Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$count',
              style: Theme.of(context).textTheme.headlineMedium,
            ),
            TextButton(child: Text("Increment"), onPressed: () => onIncrement(count + 16))
          ],
        ),
      );
  }
}