Okay, it looks like your `NoteDetailScreen` widget can't find the `NotesProvider`. This usually happens when the provider isn't placed high enough in the widget tree, above the widget that needs it. Let's ensure `NotesProvider` is available to your entire app or at least the part that includes `NoteDetailScreen`. We'll wrap your `MaterialApp` with a `ChangeNotifierProvider` for `NotesProvider`. import 'package:flutter/material.dart'; import 'package:provider/provider.dart'; import 'providers/notes_provider.dart'; // Assuming your provider is here import 'screens/notes_list_screen.dart'; // Assuming you have a list screen // Import other screens if needed, like NoteDetailScreen if used directly in routes // import 'screens/note_detail_screen.dart'; void main() { runApp( // Wrap the entire app with the provider ChangeNotifierProvider( create: (context) => NotesProvider(), // Create an instance of your provider child: const MyApp(), ), ); } class MyApp extends StatelessWidget { const MyApp({super.key}); @override Widget build(BuildContext context) { return MaterialApp( title: 'Notes App', theme: ThemeData( primarySwatch: Colors.blue, visualDensity: VisualDensity.adaptivePlatformDensity, ), // Make sure your initial screen is set correctly home: const NotesListScreen(), // If you use named routes, ensure NoteDetailScreen is defined here // or pushed via Navigator.push from a widget under MaterialApp // routes: { // '/note-detail': (context) => NoteDetailScreen(), // Example route // }, ); } } // --- Placeholder Widgets (Replace with your actual implementations) --- // Example NotesProvider (Make sure yours extends ChangeNotifier) // Place this in lib/providers/notes_provider.dart // class NotesProvider extends ChangeNotifier { // List _notes = ['First Note', 'Second Note']; // List get notes => _notes; // // void addNote(String note) { // _notes.add(note); // notifyListeners(); // } // // void deleteNote(int index) { // _notes.removeAt(index); // notifyListeners(); // } // } // Example NotesListScreen // Place this in lib/screens/notes_list_screen.dart // class NotesListScreen extends StatelessWidget { // const NotesListScreen({super.key}); // // @override // Widget build(BuildContext context) { // // Access provider here if needed // // final notesProvider = Provider.of(context); // return Scaffold( // appBar: AppBar(title: const Text('Notes')), // body: const Center(child: Text('List of notes would go here')), // floatingActionButton: FloatingActionButton( // onPressed: () { // // Example navigation to detail screen // // Navigator.push(context, MaterialPageRoute(builder: (context) => NoteDetailScreen())); // // Or using named routes: // // Navigator.pushNamed(context, '/note-detail'); // print('Navigate to add/detail screen'); // }, // child: const Icon(Icons.add), // ), // ); // } // } // Example NoteDetailScreen (Where the error likely occurred) // Place this in lib/screens/note_detail_screen.dart // class NoteDetailScreen extends StatelessWidget { // const NoteDetailScreen({super.key}); // // @override // Widget build(BuildContext context) { // // This line would cause the error if the provider is not above this widget // final notesProvider = Provider.of(context); // // return Scaffold( // appBar: AppBar(title: const Text('Note Detail')), // body: Center( // child: Text('Note details - Accessing provider: ${notesProvider.notes.length} notes total'), // ), // ); // } // } import 'package:flutter/foundation.dart'; // Example Note class (adjust as needed) class Note { final String id; final String title; final String content; final DateTime createdAt; Note({ required this.id, required this.title, required this.content, required this.createdAt, }); } class NotesProvider extends ChangeNotifier { // Use a Map for easier access by ID, or keep as List if preferred final Map _notes = {}; List get notes { final noteList = _notes.values.toList(); // Sort notes by creation date, newest first noteList.sort((a, b) => b.createdAt.compareTo(a.createdAt)); return noteList; } Note? getNoteById(String id) { return _notes[id]; } void addOrUpdateNote({String? id, required String title, required String content}) { final now = DateTime.now(); final noteId = id ?? DateTime.now().toIso8601String(); // Generate ID if adding final newNote = Note( id: noteId, title: title, content: content, createdAt: _notes[noteId]?.createdAt ?? now, // Keep original creation date if updating ); _notes[noteId] = newNote; notifyListeners(); // Notify listeners about the change } void deleteNote(String id) { _notes.remove(id); notifyListeners(); } // Add dummy data for testing if needed NotesProvider() { //_addDummyData(); } void _addDummyData() { final note1 = Note(id: '1', title: 'Grocery List', content: 'Milk, Eggs, Bread', createdAt: DateTime.now().subtract(const Duration(days: 1))); final note2 = Note(id: '2', title: 'Meeting Notes', content: 'Discuss project timeline', createdAt: DateTime.now()); _notes[note1.id] = note1; _notes[note2.id] = note2; } } import 'package:flutter/material.dart'; import 'package:provider/provider.dart'; import '../providers/notes_provider.dart'; import 'note_detail_screen.dart'; // Import detail screen class NotesListScreen extends StatelessWidget { const NotesListScreen({super.key}); @override Widget build(BuildContext context) { // Listen to changes in NotesProvider final notesProvider = context.watch(); final notes = notesProvider.notes; return Scaffold( appBar: AppBar( title: const Text('My Notes'), actions: [ IconButton( icon: const Icon(Icons.add), tooltip: 'Add Note', onPressed: () { Navigator.push( context, MaterialPageRoute( // Navigate to detail screen for adding a new note (pass null id) builder: (context) => const NoteDetailScreen(noteId: null), ), ); }, ), ], ), body: notes.isEmpty ? const Center( child: Text( 'No notes yet. Tap + to add one!', style: TextStyle(fontSize: 18, color: Colors.grey), ), ) : ListView.builder( itemCount: notes.length, itemBuilder: (context, index) { final note = notes[index]; return ListTile( title: Text(note.title.isNotEmpty ? note.title : 'Untitled Note'), subtitle: Text( note.content, maxLines: 1, overflow: TextOverflow.ellipsis, ), trailing: IconButton( icon: const Icon(Icons.delete, color: Colors.redAccent), tooltip: 'Delete Note', onPressed: () { // Show confirmation dialog before deleting showDialog( context: context, builder: (ctx) => AlertDialog( title: const Text('Delete Note?'), content: const Text('Are you sure you want to delete this note?'), actions: [ TextButton( child: const Text('Cancel'), onPressed: () { Navigator.of(ctx).pop(); // Close dialog }, ), TextButton( child: const Text('Delete', style: TextStyle(color: Colors.red)), onPressed: () { // Use context.read inside callbacks/functions context.read().deleteNote(note.id); Navigator.of(ctx).pop(); // Close dialog }, ), ], ), ); }, ), onTap: () { Navigator.push( context, MaterialPageRoute( // Navigate to detail screen for editing (pass note id) builder: (context) => NoteDetailScreen(noteId: note.id), ), ); }, ); }, ), // Moved the FAB to AppBar actions for consistency // floatingActionButton: FloatingActionButton( // onPressed: () { // Navigator.push( // context, // MaterialPageRoute( // builder: (context) => const NoteDetailScreen(noteId: null), // ), // ); // }, // tooltip: 'Add Note', // child: const Icon(Icons.add), // ), ); } } import 'package:flutter/material.dart'; import 'package:provider/provider.dart'; import '../providers/notes_provider.dart'; class NoteDetailScreen extends StatefulWidget { final String? noteId; // Null if creating a new note const NoteDetailScreen({super.key, this.noteId}); @override State createState() => _NoteDetailScreenState(); } class _NoteDetailScreenState extends State { final _titleController = TextEditingController(); final _contentController = TextEditingController(); final _formKey = GlobalKey(); // For validation if needed bool _isInit = true; Note? _existingNote; @override void didChangeDependencies() { super.didChangeDependencies(); if (_isInit) { if (widget.noteId != null) { // Fetch existing note data if editing _existingNote = context.read().getNoteById(widget.noteId!); if (_existingNote != null) { _titleController.text = _existingNote!.title; _contentController.text = _existingNote!.content; } else { // Handle case where noteId is provided but note not found (optional) // Maybe show an error or pop the screen print("Error: Note with ID ${widget.noteId} not found."); // Consider popping: WidgetsBinding.instance.addPostFrameCallback((_) => Navigator.of(context).pop()); } } _isInit = false; } } @override void dispose() { _titleController.dispose(); _contentController.dispose(); super.dispose(); } void _saveNote() { // Basic validation (optional, enhance as needed) // if (!_formKey.currentState!.validate()) { // return; // } // _formKey.currentState!.save(); // If using Form widgets final title = _titleController.text; final content = _contentController.text; // Prevent saving empty notes (optional) if (title.isEmpty && content.isEmpty) { ScaffoldMessenger.of(context).showSnackBar( const SnackBar(content: Text('Cannot save an empty note.')), ); return; } // Use context.read in callbacks/functions context.read().addOrUpdateNote( id: widget.noteId, // Pass existing ID if editing title: title, content: content, ); Navigator.of(context).pop(); // Go back to the list screen } @override Widget build(BuildContext context) { // No need to call Provider.of here if only using it in callbacks (like _saveNote) // If you needed to display something reactive based on the provider state, // you would use context.watch() here. return Scaffold( appBar: AppBar( title: Text(widget.noteId == null ? 'Add Note' : 'Edit Note'), actions: [ IconButton( icon: const Icon(Icons.save), tooltip: 'Save Note', onPressed: _saveNote, // Call the save function ), ], ), body: Padding( padding: const EdgeInsets.all(16.0), child: Form( // Using Form for potential future validation key: _formKey, child: Column( children: [ TextFormField( controller: _titleController, decoration: const InputDecoration( labelText: 'Title', hintText: 'Enter note title', border: OutlineInputBorder(), ), style: const TextStyle(fontSize: 18, fontWeight: FontWeight.bold), textInputAction: TextInputAction.next, // Add validator if needed // validator: (value) { // if (value == null || value.isEmpty) { // return 'Please enter a title'; // } // return null; // }, ), const SizedBox(height: 16.0), Expanded( child: TextFormField( controller: _contentController, decoration: const InputDecoration( labelText: 'Content', hintText: 'Enter note content...', border: OutlineInputBorder(), alignLabelWithHint: true, // Better alignment for multi-line ), maxLines: null, // Allows unlimited lines expands: true, // Fills available space keyboardType: TextInputType.multiline, textAlignVertical: TextAlignVertical.top, // Start cursor at top // Add validator if needed // validator: (value) { // if (value == null || value.isEmpty) { // return 'Please enter content'; // } // return null; // }, ), ), ], ), ), ), ); } } name: notes_app # Changed from codeshastra_app for clarity description: "A simple notes application using Flutter and Provider." publish_to: 'none' # Remove this line if you intend to publish to pub.dev version: 1.0.0+1 environment: sdk: '>=3.0.0 <4.0.0' # Updated to Dart 3 syntax dependencies: flutter: sdk: flutter provider: ^6.0.0 # Add provider package cupertino_icons: ^1.0.2 dev_dependencies: flutter_test: sdk: flutter flutter_lints: ^2.0.0 # Or ^3.0.0 if available flutter: uses-material-design: true **Explanation:** 1. **`main.dart`:** We wrap the `MyApp` widget (which contains `MaterialApp`) with `ChangeNotifierProvider`. This makes a single instance of `NotesProvider` available to all widgets below it in the tree, including any screens pushed onto the `Navigator`. 2. **`providers/notes_provider.dart`:** This file should contain your `NotesProvider` class, which must extend `ChangeNotifier`. It holds the notes data and methods to modify it (like `addNote`, `deleteNote`), calling `notifyListeners()` after any data change. (A basic structure is provided). 3. **`screens/notes_list_screen.dart`:** This screen can now safely access the provider using `context.watch()` (to rebuild when data changes) or `context.read()` (to just read data or call methods, typically used in callbacks like `onPressed`). 4. **`screens/note_detail_screen.dart`:** This screen, when pushed via `Navigator` from `NotesListScreen` (or any widget under `MyApp`), will also have access to the same `NotesProvider` instance. 5. **`pubspec.yaml`:** Ensure you have the `provider` package listed under dependencies. Run `flutter pub get` if you add it. After applying these changes, perform a **Hot Restart** (not just Hot Reload) in your IDE or run `flutter run` again. This should resolve the `ProviderNotFoundError`.