6 तरीके Flutter Apps में State को Manage करने के (Code Examples के साथ)

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(home: CounterScreen());
  }
}

class CounterScreen extends StatefulWidget {
  @override
  _CounterScreenState createState() => _CounterScreenState();
}

class _CounterScreenState extends State<CounterScreen> {
  int _count = 0;

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

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('setState Counter')),
      body: Center(
        child: Text('Count: $_count', style: TextStyle(fontSize: 24)),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _increment,
        child: Icon(Icons.add),
      ),
    );
  }
}

import 'package:flutter/material.dart';

// वह InheritedWidget जो थीम डेटा को रखता है
class AppTheme extends InheritedWidget {
  final bool isDarkMode;
  final Function toggleTheme;

  const AppTheme({
    Key? key,
    required this.isDarkMode,
    required this.toggleTheme,
    required Widget child,
  }) : super(key: key, child: child);

  // विधि Access करने के लिए सबसे नजदीकी AppTheme को विड्जेट ट्री के ऊपर
  static AppTheme? of(BuildContext context) {
    return context.dependOnInheritedWidgetOfExactType<AppTheme>();
  }

  @override
  bool updateShouldNotify(AppTheme oldWidget) {
    return isDarkMode != oldWidget.isDarkMode;
  }
}

// Stateful wrapper स्टेट परिवर्तनों को प्रबंधित करने के लिए
class ThemeManager extends StatefulWidget {
  final Widget child;

  const ThemeManager({Key? key, required this.child}) : super(key: key);

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

class _ThemeManagerState extends State<ThemeManager> {
  bool _isDarkMode = false;

  void _toggleTheme() {
    setState(() {
      _isDarkMode = !_isDarkMode;
    });
  }

  @override
  Widget build(BuildContext context) {
    return AppTheme(
      isDarkMode: _isDarkMode,
      toggleTheme: _toggleTheme,
      child: widget.child,
    );
  }
}

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return ThemeManager(
      child: Builder(
        builder: (context) {
          final theme = AppTheme.of(context);
          return MaterialApp(
            theme: theme!.isDarkMode ? ThemeData.dark() : ThemeData.light(),
            home: HomeScreen(),
          );
        },
      ),
    );
  }
}

class HomeScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    final theme = AppTheme.of(context);

    return Scaffold(
      appBar: AppBar(title: Text('InheritedWidget Theme')),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Text(
              'Current Theme: ${theme!.isDarkMode ? "Dark" : "Light"}',
              style: TextStyle(fontSize: 20),
            ),
            SizedBox(height: 20),
            ElevatedButton(
              onPressed: () => theme.toggleTheme(),
              child: Text('Toggle Theme'),
            ),
          ],
        ),
      ),
    );
  }
}

dependencies:
  provider: ^6.0.5

import 'package:flutter/material.dart';
import 'package:provider/provider.dart';

void main() {
  runApp(
    ChangeNotifierProvider(
      create: (_) => CounterModel(),
      child: MyApp(),
    ),
  );
}

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

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(home: CounterScreen());
  }
}

class CounterScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    final counter = context.watch<CounterModel>();
    return Scaffold(
      appBar: AppBar(title: Text('Provider Counter')),
      body: Center(
        child: Text('Count: ${counter.count}', style: TextStyle(fontSize: 24)),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: context.read<CounterModel>().increment,
        child: Icon(Icons.add),
      ),
    );
  }
}

dependencies:
  flutter_riverpod: ^2.4.0

import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';

// मॉडल
class UserProfile {
  final String name;
  final int age;

  UserProfile({required this.name, required this.age});

  UserProfile copyWith({String? name, int? age}) {
    return UserProfile(
      name: name ?? this.name,
      age: age ?? this.age,
    );
  }
}

// स्टेट नोटिफायर
class ProfileNotifier extends StateNotifier<UserProfile> {
  ProfileNotifier() : super(UserProfile(name: 'Guest', age: 0));

  void updateName(String name) {
    state = state.copyWith(name: name);
  }

  void updateAge(int age) {
    state = state.copyWith(age: age);
  }
}

// प्रोवाइडर
final profileProvider = StateNotifierProvider<ProfileNotifier, UserProfile>((ref) {
  return ProfileNotifier();
});

// कंप्यूटेड प्रोवाइडर
final greetingProvider = Provider<String>((ref) {
  final profile = ref.watch(profileProvider);
  return 'नमस्ते, ${profile.name}! आप ${profile.age} वर्ष के हैं।';
});

void main() {
  runApp(
    ProviderScope(
      child: MyApp(),
    ),
  );
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(home: ProfileScreen());
  }
}

class ProfileScreen extends ConsumerWidget {
  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final profile = ref.watch(profileProvider);
    final greeting = ref.watch(greetingProvider);

    return Scaffold(
      appBar: AppBar(title: Text('Riverpod प्रोफ़ाइल')),
      body: Padding(
        padding: EdgeInsets.all(16),
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Text(greeting, style: TextStyle(fontSize: 20)),
            SizedBox(height: 30),
            TextField(
              decoration: InputDecoration(labelText: 'नाम'),
              onChanged: (value) {
                ref.read(profileProvider.notifier).updateName(value);
              },
            ),
            SizedBox(height: 20),
            Row(
              mainAxisAlignment: MainAxisAlignment.center,
              children: [
                Text('उम्र: ${profile.age}', style: TextStyle(fontSize: 18)),
                SizedBox(width: 20),
                ElevatedButton(
                  onPressed: () {
                    ref.read(profileProvider.notifier).updateAge(profile.age + 1);
                  },
                  child: Text('+'),
                ),
                SizedBox(width: 10),
                ElevatedButton(
                  onPressed: () {
                    if (profile.age > 0) {
                      ref.read(profileProvider.notifier).updateAge(profile.age - 1);
                    }
                  },
                  child: Text('-'),
                ),
              ],
            ),
          ],
        ),
      ),
    );
  }
}

dependencies:
  flutter_bloc: ^9.0.0

import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';

// इवेंट्स
abstract class CounterEvent {}
class Increment extends CounterEvent {}

// Bloc
class CounterBloc extends Bloc<CounterEvent, int> {
  CounterBloc() : super(0) {
    on<Increment>((event, emit) => emit(state + 1));
  }
}

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return BlocProvider(
      create: (_) => CounterBloc(),
      child: MaterialApp(home: CounterScreen()),
    );
  }
}

class CounterScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Bloc काउंटर')),
      body: Center(
        child: BlocBuilder<CounterBloc, int>(
          builder: (context, count) {
            return Text('काउंट: $count', style: TextStyle(fontSize: 24));
          },
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () => context.read<CounterBloc>().add(Increment()),
        child: Icon(Icons.add),
      ),
    );
  }
}

dependencies:
  get: ^4.6.5

import 'package:flutter/material.dart';
import 'package:get/get.dart';

// कंट्रोलर
class ShoppingController extends GetxController {
  // अवलोकन सूची
  var items = <String>[].obs;

  // अवलोकन काउंटर
  var totalItems = 0.obs;

  void addItem(String item) {
    if (item.isNotEmpty) {
      items.add(item);
      totalItems.value = items.length;
    }
  }

  void removeItem(int index) {
    items.removeAt(index);
    totalItems.value = items.length;
  }

  void clearAll() {
    items.clear();
    totalItems.value = 0;
  }
}

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return GetMaterialApp(
      title: 'GetX शॉपिंग लिस्ट',
      home: ShoppingScreen(),
    );
  }
}

class ShoppingScreen extends StatelessWidget {
  // कंट्रोलर इनिशियलाइज़ करें
  final ShoppingController controller = Get.put(ShoppingController());
  final TextEditingController textController = TextEditingController();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('GetX शॉपिंग लिस्ट'),
        actions: [
          Obx(() => Padding(
                padding: EdgeInsets.all(16),
                child: Center(
                  child: Text(
                    'आइटम्स: ${controller.totalItems}',
                    style: TextStyle(fontSize: 18),
                  ),
                ),
              )),
        ],
      ),
      body: Column(
        children: [
          Padding(
            padding: EdgeInsets.all(16),
            child: Row(
              children: [
                Expanded(
                  child: TextField(
                    controller: textController,
                    decoration: InputDecoration(
                      hintText: 'आइटम का नाम दर्ज करें',
                      border: OutlineInputBorder(),
                    ),
                  ),
                ),
                SizedBox(width: 10),
                ElevatedButton(
                  onPressed: () {
                    controller.addItem(textController.text);
                    textController.clear();
                  },
                  child: Icon(Icons.add),
                ),
              ],
            ),
          ),
          Expanded(
            child: Obx(() {
              if (controller.items.isEmpty) {
                return Center(
                  child: Text('आपकी सूची में कोई आइटम नहीं है'),
                );
              }

              return ListView.builder(
                itemCount: controller.items.length,
                itemBuilder: (context, index) {
                  return ListTile(
                    leading: CircleAvatar(child: Text('${index + 1}')),
                    title: Text(controller.items[index]),
                    trailing: IconButton(
                      icon: Icon(Icons.delete, color: Colors.red),
                      onPressed: () => controller.removeItem(index),
                    ),
                  );
                },
              );
            }),
          ),
          if (controller.items.isNotEmpty)
            Padding(
              padding: EdgeInsets.all(16),
              child: ElevatedButton(
                onPressed: () {
                  Get.defaultDialog(
                    title: 'सूची साफ करें',
                    middleText: 'क्या आप सभी आइटम्स को साफ करने की पुष्टि करते हैं?',
                    textConfirm: 'हाँ',
                    textCancel: 'नहीं',
                    onConfirm: () {
                      controller.clearAll();
                      Get.back();
                    },
                  );
                },
                style: ElevatedButton.styleFrom(
                  backgroundColor: Colors.red,
                  minimumSize: Size(double.infinity, 50),
                ),
                child: Text('सभी साफ करें'),
              ),
            ),
        ],
      ),
    );
  }
}