Flutter Cheat Sheet

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',
      home: const HomePage(),
    );
  }
}

Scaffold(
  appBar: AppBar(
    title: const Text('My App'),
  ),
  body: const Center(
    child: Text('Hello, Flutter!'),
  ),
)

Text(
  'Hello, Flutter!',
  style: TextStyle(
    fontSize: 24,
    fontWeight: FontWeight.bold,
    color: Colors.blue,
  ),
)

Container(
  width: 100,
  height: 100,
  padding: const EdgeInsets.all(16),
  margin: const EdgeInsets.all(8),
  decoration: BoxDecoration(
    color: Colors.blue,
    borderRadius: BorderRadius.circular(8),
  ),
  child: const Text('Box'),
)

Row(
  mainAxisAlignment: MainAxisAlignment.spaceEvenly,
  children: [
    Icon(Icons.star),
    Text('Rating'),
    Icon(Icons.star),
  ],
)

Column(
  crossAxisAlignment: CrossAxisAlignment.start,
  children: [
    Text('Title'),
    Text('Subtitle'),
  ],
)

// Network image
Image.network(
  'https://example.com/image.png',
  width: 200,
  height: 200,
)

// Asset image
Image.asset('assets/logo.png')

Icon(
  Icons.favorite,
  color: Colors.red,
  size: 32,
)

ElevatedButton(
  onPressed: () {
    print('Pressed');
  },
  child: const Text('Click Me'),
)

TextButton(
  onPressed: () {},
  child: const Text('Text Button'),
)

IconButton(
  icon: const Icon(Icons.add),
  onPressed: () {},
)

Center(
  child: Text('Centered Text'),
)

Padding(
  padding: const EdgeInsets.all(16.0),
  child: Text('Padded Text'),
)

// Specific edges
Padding(
  padding: const EdgeInsets.only(
    left: 16,
    top: 8,
  ),
  child: Text('Custom Padding'),
)

Stack(
  children: [
    Container(color: Colors.blue, width: 200, height: 200),
    Positioned(
      top: 20,
      left: 20,
      child: Text('Overlay'),
    ),
  ],
)

Row(
  children: [
    Expanded(
      flex: 2,
      child: Container(color: Colors.blue),
    ),
    Expanded(
      flex: 1,
      child: Container(color: Colors.red),
    ),
  ],
)

ListView(
  children: [
    ListTile(title: Text('Item 1')),
    ListTile(title: Text('Item 2')),
    ListTile(title: Text('Item 3')),
  ],
)

// ListView.builder for dynamic lists
ListView.builder(
  itemCount: items.length,
  itemBuilder: (context, index) {
    return ListTile(title: Text(items[index]));
  },
)

GridView.count(
  crossAxisCount: 2,
  children: List.generate(6, (index) {
    return Card(
      child: Center(
        child: Text('Item $index'),
      ),
    );
  }),
)

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

  @override
  State<Counter> createState() => _CounterState();
}

class _CounterState extends State<Counter> {
  int _count = 0;

  @override
  Widget build(BuildContext context) {
    return Text('$_count');
  }
}

void _incrementCounter() {
  setState(() {
    _count++;
  });
}

@override
void initState() {
  super.initState();
  // Initialize state
}

@override
void dispose() {
  // Cleanup
  super.dispose();
}

class MyForm extends StatefulWidget {
  @override
  State<MyForm> createState() => _MyFormState();
}

class _MyFormState extends State<MyForm> {
  final _controller = TextEditingController();

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return TextField(
      controller: _controller,
    );
  }
}

Navigator.push(
  context,
  MaterialPageRoute(
    builder: (context) => const SecondScreen(),
  ),
);

Navigator.pop(context);

// In MaterialApp
MaterialApp(
  initialRoute: '/',
  routes: {
    '/': (context) => const HomeScreen(),
    '/details': (context) => const DetailsScreen(),
  },
)

// Navigate using named route
Navigator.pushNamed(context, '/details');

Navigator.push(
  context,
  MaterialPageRoute(
    builder: (context) => DetailsScreen(
      item: myItem,
    ),
  ),
);

// In DetailsScreen
class DetailsScreen extends StatelessWidget {
  final Item item;

  const DetailsScreen({required this.item});
}

// In first screen
final result = await Navigator.push(
  context,
  MaterialPageRoute(builder: (context) => SelectionScreen()),
);

// In second screen
Navigator.pop(context, 'Selected Value');

TextField(
  decoration: const InputDecoration(
    border: OutlineInputBorder(),
    labelText: 'Username',
    hintText: 'Enter your username',
  ),
  onChanged: (value) {
    print(value);
  },
)

final _formKey = GlobalKey<FormState>();

Form(
  key: _formKey,
  child: Column(
    children: [
      TextFormField(
        validator: (value) {
          if (value == null || value.isEmpty) {
            return 'Please enter some text';
          }
          return null;
        },
      ),
      ElevatedButton(
        onPressed: () {
          if (_formKey.currentState!.validate()) {
            // Process form
          }
        },
        child: const Text('Submit'),
      ),
    ],
  ),
)

Checkbox(
  value: _isChecked,
  onChanged: (bool? value) {
    setState(() {
      _isChecked = value!;
    });
  },
)

Switch(
  value: _isEnabled,
  onChanged: (bool value) {
    setState(() {
      _isEnabled = value;
    });
  },
)

FutureBuilder<String>(
  future: fetchData(),
  builder: (context, snapshot) {
    if (snapshot.hasData) {
      return Text(snapshot.data!);
    } else if (snapshot.hasError) {
      return Text('Error: ${snapshot.error}');
    }
    return const CircularProgressIndicator();
  },
)

// pubspec.yaml: http: ^1.1.0
import 'package:http/http.dart' as http;
import 'dart:convert';

Future<Album> fetchAlbum() async {
  final response = await http.get(
    Uri.parse('https://api.example.com/albums/1'),
  );

  if (response.statusCode == 200) {
    return Album.fromJson(jsonDecode(response.body));
  } else {
    throw Exception('Failed to load album');
  }
}

Future<Album> createAlbum(String title) async {
  final response = await http.post(
    Uri.parse('https://api.example.com/albums'),
    headers: <String, String>{
      'Content-Type': 'application/json; charset=UTF-8',
    },
    body: jsonEncode(<String, String>{
      'title': title,
    }),
  );

  if (response.statusCode == 201) {
    return Album.fromJson(jsonDecode(response.body));
  } else {
    throw Exception('Failed to create album');
  }
}

// pubspec.yaml: provider: ^6.0.0
import 'package:flutter/foundation.dart';

class Counter extends ChangeNotifier {
  int _count = 0;

  int get count => _count;

  void increment() {
    _count++;
    notifyListeners();
  }
}

import 'package:provider/provider.dart';

void main() {
  runApp(
    ChangeNotifierProvider(
      create: (context) => Counter(),
      child: const MyApp(),
    ),
  );
}

Consumer<Counter>(
  builder: (context, counter, child) {
    return Text('${counter.count}');
  },
)

final counter = Provider.of<Counter>(context);

ElevatedButton(
  onPressed: counter.increment,
  child: const Text('Increment'),
)