📱

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

Row(
  mainAxisAlignment: MainAxisAlignment.spaceBetween,
  crossAxisAlignment: CrossAxisAlignment.center,
  children: [
    Text('Left'),
    Text('Right'),
  ],
)

Column(
  mainAxisAlignment: MainAxisAlignment.center,
  children: [
    Text('Top'),
    Text('Bottom'),
  ],
)

Stack(
  children: [
    Container(color: Colors.blue),
    Positioned(
      top: 10,
      left: 10,
      child: Text('Overlay'),
    ),
  ],
)

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

SizedBox(width: 20, height: 20)
SizedBox.expand()  // Fill parent

Text(
  'Hello World',
  style: TextStyle(
    fontSize: 24,
    fontWeight: FontWeight.bold,
    color: Colors.blue,
  ),
  textAlign: TextAlign.center,
  maxLines: 2,
  overflow: TextOverflow.ellipsis,
)

Image.network('https://example.com/image.png')
Image.asset('assets/image.png')
Image.file(File('path/to/file'))

Icon(Icons.home, size: 24, color: Colors.blue)

ElevatedButton(
  onPressed: () {},
  child: Text('Click'),
)

TextButton(onPressed: () {}, child: Text('Text'))
IconButton(icon: Icon(Icons.add), onPressed: () {})

TextField(
  controller: _controller,
  decoration: InputDecoration(
    labelText: 'Email',
    hintText: 'Enter email',
    prefixIcon: Icon(Icons.email),
  ),
  onChanged: (value) {},
  onSubmitted: (value) {},
)

class CounterWidget extends StatefulWidget {
  @override
  _CounterWidgetState createState() => _CounterWidgetState();
}

class _CounterWidgetState extends State<CounterWidget> {
  int _counter = 0;

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

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        Text('Count: $_counter'),
        ElevatedButton(
          onPressed: _increment,
          child: Text('Increment'),
        ),
      ],
    );
  }
}

class CounterProvider extends ChangeNotifier {
  int _count = 0;
  int get count => _count;

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

ChangeNotifierProvider(
  create: (context) => CounterProvider(),
  child: MyApp(),
)

// Watch for changes
final count = context.watch<CounterProvider>().count;

// Read without rebuilding
final provider = context.read<CounterProvider>();
provider.increment();

Consumer<CounterProvider>(
  builder: (context, provider, child) {
    return Text('Count: ${provider.count}');
  },
)

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

Navigator.pop(context);
Navigator.pop(context, result);  // With result

Navigator.pushReplacement(
  context,
  MaterialPageRoute(builder: (context) => HomePage()),
);

Navigator.pushAndRemoveUntil(
  context,
  MaterialPageRoute(builder: (context) => LoginPage()),
  (route) => false,
);

// Define routes
MaterialApp(
  routes: {
    '/': (context) => HomePage(),
    '/details': (context) => DetailsPage(),
  },
);

// Navigate
Navigator.pushNamed(context, '/details');
Navigator.pushNamed(context, '/details', arguments: data);

final args = ModalRoute.of(context)!.settings.arguments;

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

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

ListView.separated(
  itemCount: items.length,
  separatorBuilder: (context, index) => Divider(),
  itemBuilder: (context, index) {
    return ListTile(title: Text(items[index]));
  },
)

GridView.builder(
  gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
    crossAxisCount: 2,
    crossAxisSpacing: 10,
    mainAxisSpacing: 10,
  ),
  itemCount: items.length,
  itemBuilder: (context, index) {
    return Card(child: Text(items[index]));
  },
)

FutureBuilder<String>(
  future: fetchData(),
  builder: (context, snapshot) {
    if (snapshot.connectionState == ConnectionState.waiting) {
      return CircularProgressIndicator();
    }
    if (snapshot.hasError) {
      return Text('Error: ${snapshot.error}');
    }
    return Text('Data: ${snapshot.data}');
  },
)

StreamBuilder<int>(
  stream: counterStream,
  builder: (context, snapshot) {
    if (!snapshot.hasData) {
      return CircularProgressIndicator();
    }
    return Text('Count: ${snapshot.data}');
  },
)

import 'package:http/http.dart' as http;

Future<String> fetchData() async {
  final response = await http.get(
    Uri.parse('https://api.example.com/data'),
  );
  if (response.statusCode == 200) {
    return response.body;
  }
  throw Exception('Failed to load');
}

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 data
          }
        },
        child: Text('Submit'),
      ),
    ],
  ),
)

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

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

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

class _MyWidgetState extends State<MyWidget> {
  @override
  void initState() {
    super.initState();
    // Called once when widget is created
  }

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    // Called when dependencies change
  }

  @override
  void didUpdateWidget(MyWidget oldWidget) {
    super.didUpdateWidget(oldWidget);
    // Called when parent rebuilds
  }

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

  @override
  Widget build(BuildContext context) {
    return Container();
  }
}