mirror of
https://github.com/nisrulz/flutter-examples.git
synced 2026-08-25 01:05:36 +00:00
refactor: split app wrapper from focused example code (complex apps)
Convert the final 12 multi-screen apps to the validated pattern: lib/main.dart keeps only the MaterialApp bootstrap (plus firebase init where that is genuine bootstrap), and a new lib/example.dart holds the entry screen and focused example code, importing existing supporting files. firebase_crash keeps its runZonedGuarded bootstrap in main.dart and extracts only CrashApp. Apps: bmi_calculator, covid19_mobile_app, expense_planner, firebase_crash_reporting, firebase_google_authentication, lunch_app, navigation_drawer, news_memes_app, save_data_locally_with_sqlite, todo_list_using_provider, unit_testing, using_firebase_db
This commit is contained in:
Nishant Srivastava
128
using_firebase_db/lib/example.dart
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128
using_firebase_db/lib/example.dart
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@@ -0,0 +1,128 @@
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// Example: Store and manage notes in a Firebase Realtime Database.
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import 'dart:async';
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import 'package:firebase_database/firebase_database.dart';
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import 'package:flutter/material.dart';
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class Note {
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late String id;
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late String content;
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late String createdOn;
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Note(this.content) {
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createdOn = DateTime.now().toString();
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}
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}
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class Example extends StatefulWidget {
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const Example({super.key});
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@override
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_ExampleState createState() => _ExampleState();
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}
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class _ExampleState extends State<Example> {
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final notesRef = FirebaseDatabase.instance.ref().child('notes');
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final inputController = TextEditingController();
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late StreamSubscription<DatabaseEvent> _noteAddedStream;
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List<Note> items = [];
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@override
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void initState() {
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super.initState();
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_noteAddedStream =
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notesRef.orderByChild("created_on").onChildAdded.listen(_onNoteAdded);
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}
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// Creates a new child under notes in the database
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void _addNote() {
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var note = Note(inputController.text);
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inputController.text = "";
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if (note.content.isNotEmpty) {
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notesRef.push().set({
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'content': note.content,
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'created_on': note.createdOn,
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});
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}
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}
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// Fired whenever the database sees a new child under the notes
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// database reference
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void _onNoteAdded(DatabaseEvent event) {
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setState(() {
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final value = event.snapshot.value as Map;
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var note = Note(value["content"] as String);
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note.id = event.snapshot.key!;
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note.createdOn = value["created_on"] as String;
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items.add(note);
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});
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}
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@override
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void dispose() {
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_noteAddedStream.cancel();
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super.dispose();
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}
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// The note has to be cleared from the database and the local list
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void _deleteNote(int position) {
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String id = items[position].id;
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notesRef.child(id).remove().then((_) {
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setState(() {
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items.removeAt(position);
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});
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});
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}
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@override
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Widget build(BuildContext context) {
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return Scaffold(
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appBar: AppBar(
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title: Text("Using Firebase DB"),
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),
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body: Center(
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child: Column(
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mainAxisAlignment: MainAxisAlignment.center,
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children: <Widget>[
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Container(
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padding: EdgeInsets.all(15.0),
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child: TextField(
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style:
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TextStyle(fontSize: 24.0, height: 2.0, color: Colors.black),
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decoration: InputDecoration(
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border: InputBorder.none, hintText: 'Add a note'),
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controller: inputController,
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),
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),
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Expanded(
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child: SizedBox(
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height: 200.0,
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child: ListView.builder(
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itemCount: items.length,
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padding: const EdgeInsets.all(10.0),
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itemBuilder: (context, position) {
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return Card(
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child: ListTile(
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leading: Icon(Icons.note),
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title: Text(items[position].content),
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onLongPress: () {
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_deleteNote(position);
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},
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),
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);
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}),
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),
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),
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],
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),
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),
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floatingActionButton: FloatingActionButton(
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onPressed: _addNote,
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tooltip: 'Add Note',
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child: Icon(Icons.add),
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),
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);
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}
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}
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@@ -1,19 +1,8 @@
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import 'dart:async';
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import 'package:firebase_database/firebase_database.dart';
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import 'package:flutter/material.dart';
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class Note {
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late String id;
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late String content;
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late String createdOn;
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import 'example.dart';
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Note(this.content) {
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createdOn = DateTime.now().toString();
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}
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}
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void main() => runApp(MyApp());
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void main() => runApp(const MyApp());
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class MyApp extends StatelessWidget {
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const MyApp({super.key});
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@@ -25,120 +14,7 @@ class MyApp extends StatelessWidget {
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theme: ThemeData(
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primarySwatch: Colors.blue,
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),
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home: MyHomePage(title: 'Firebase demo'),
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);
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}
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}
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class MyHomePage extends StatefulWidget {
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const MyHomePage({super.key, required this.title});
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final String title;
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@override
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_MyHomePageState createState() => _MyHomePageState();
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}
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class _MyHomePageState extends State<MyHomePage> {
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final notesRef = FirebaseDatabase.instance.ref().child('notes');
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final inputController = TextEditingController();
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late StreamSubscription<DatabaseEvent> _noteAddedStream;
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List<Note> items = [];
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@override
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void initState() {
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super.initState();
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_noteAddedStream =
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notesRef.orderByChild("created_on").onChildAdded.listen(_onNoteAdded);
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}
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// Creates a new child under notes in the database
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void _addNote() {
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var note = Note(inputController.text);
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inputController.text = "";
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if (note.content.isNotEmpty) {
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notesRef.push().set({
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'content': note.content,
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'created_on': note.createdOn,
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});
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}
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}
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// Fired whenever the database sees a new child under the notes
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// database reference
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void _onNoteAdded(DatabaseEvent event) {
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setState(() {
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final value = event.snapshot.value as Map;
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var note = Note(value["content"] as String);
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note.id = event.snapshot.key!;
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note.createdOn = value["created_on"] as String;
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items.add(note);
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});
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}
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@override
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void dispose() {
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_noteAddedStream.cancel();
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super.dispose();
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}
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// The note has to be cleared from the database and the local list
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void _deleteNote(int position) {
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String id = items[position].id;
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notesRef.child(id).remove().then((_) {
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setState(() {
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items.removeAt(position);
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});
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});
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}
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@override
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Widget build(BuildContext context) {
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return Scaffold(
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appBar: AppBar(
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title: Text("Using Firebase DB"),
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),
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body: Center(
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child: Column(
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mainAxisAlignment: MainAxisAlignment.center,
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children: <Widget>[
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Container(
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padding: EdgeInsets.all(15.0),
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child: TextField(
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style:
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TextStyle(fontSize: 24.0, height: 2.0, color: Colors.black),
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decoration: InputDecoration(
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border: InputBorder.none, hintText: 'Add a note'),
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controller: inputController,
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),
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),
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Expanded(
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child: SizedBox(
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height: 200.0,
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child: ListView.builder(
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itemCount: items.length,
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padding: const EdgeInsets.all(10.0),
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itemBuilder: (context, position) {
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return Card(
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child: ListTile(
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leading: Icon(Icons.note),
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title: Text(items[position].content),
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onLongPress: () {
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_deleteNote(position);
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},
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),
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);
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}),
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),
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),
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],
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),
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),
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floatingActionButton: FloatingActionButton(
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onPressed: _addNote,
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tooltip: 'Add Note',
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child: Icon(Icons.add),
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),
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home: const Example(),
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);
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}
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}
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