List is not updating - Flutter - flutter

Question

I've saw a code snippet for my app that i wanted to usw.. my problem now is that when i'm typing a new task into the app, my app just won't show that to the screen until a hot reload of the app. But first the user can't do any hot reloads AND for user experience it's very bad. If you need more code or debug things, please ask in the comments!
Here i the code (Ig it's this part thats not updating):
tasks_data.dart
import 'package:flutter/material.dart';
import 'package:flutter/foundation.dart';
import 'package:learnon/models/task.dart';
import 'dart:collection';
import 'package:shared_preferences/shared_preferences.dart';
int id = 0;
List<Task> _taskList = [];
class TaskData extends ChangeNotifier {
List<String>? task = [];
List<String>? boxValue = [];
List<String>? dates = [];
List<String>? uid = [];
Future getData() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
//prefs.clear();
task!.clear();
boxValue!.clear();
_taskList.clear();
task = prefs.getStringList("task");
boxValue = prefs.getStringList("check");
dates = prefs.getStringList("date");
uid = prefs.getStringList("id");
if (task == null) {
task = ["Long Press to clear tasks"];
boxValue = ["false"];
dates = ["2021-05-24 02:18:04Z"];
uid = [id.toString()];
}
for (int i = 0; i < boxValue!.length; i++) {
_taskList.add(Task(
name: task![i],
isDone: boxValue![i] == 'true',
date: DateTime.parse(dates![i]),
id: int.parse(uid![i])));
}
id = int.parse(uid!.last);
id += 2;
notifyListeners();
}
void setData() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
task!.clear();
boxValue!.clear();
dates!.clear();
uid!.clear();
for (int i = 0; i < _taskList.length; i++) {
task!.add(_taskList[i].name!);
boxValue!.add(_taskList[i].isDone.toString());
dates!.add(_taskList[i].date.toString());
uid!.add(_taskList[i].id.toString());
}
await prefs.setStringList("task", task!);
await prefs.setStringList("check", boxValue!);
await prefs.setStringList("date", dates!);
await prefs.setStringList("id", uid!);
notifyListeners();
}
UnmodifiableListView<Task> get tasks {
return UnmodifiableListView(_taskList);
}
void addTask(String t, DateTime d, int uid) {
_taskList.add(Task(name: t, date: d, id: uid));
setData();
notifyListeners();
}
int get taskCount {
return _taskList.length;
}
void updateTask(Task task) {
task.toggleDone();
setData();
notifyListeners();
}
void deleteTask(Task t) {
_taskList.remove(t);
setData();
notifyListeners();
}
}
tasksscreen.dart
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:learnon/widgets/tasks_list.dart';
import 'package:learnon/screens/add_task_screen.dart';
import 'package:learnon/models/tasks_data.dart';
import 'package:provider/provider.dart';
import 'package:flutter_local_notifications/flutter_local_notifications.dart';
import '../widgets/app_drawer.dart';
bool theme = false;
FlutterLocalNotificationsPlugin flutterLocalNotificationsPlugin =
FlutterLocalNotificationsPlugin();
class TasksScreenNew extends StatelessWidget {
static const routeName = "/tasksnew";
#override
Widget build(BuildContext context) {
return ChangeNotifierProvider<TaskData>(
create: (_) => TaskData(),
builder: (context, __) => Scaffold(
appBar: AppBar(
title: Text("Tasks"),
centerTitle: true,
),
drawer: AppDrawer(),
backgroundColor: Colors.blueAccent,
floatingActionButton: FloatingActionButton(
heroTag: null,
child: Icon(Icons.add),
backgroundColor: Colors.lightBlue,
onPressed: () {
showModalBottomSheet(
isScrollControlled: true,
context: context,
builder: (BuildContext context) => AddTaskScreen());
},
),
body: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
Container(
padding: EdgeInsets.only(
top: 60, left: 30, right: 30, bottom: 30),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
Builder(
builder: (context) => FloatingActionButton(
onPressed: () {},
backgroundColor: Colors.black,
child: Icon(
Icons.refresh,
color: Colors.blueAccent,
size: 30,
),
),
),
SizedBox(
height: 10,
),
Text(
'Tasks',
style: TextStyle(
color: Colors.white,
fontSize: 50,
fontWeight: FontWeight.bold),
),
Text(
'${Provider.of<TaskData>(context).taskCount} Task(s) übrig',
style: TextStyle(fontSize: 18, color: Colors.white),
),
],
),
),
Expanded(
child: Container(
padding: EdgeInsets.symmetric(horizontal: 20),
child: TasksList(),
decoration: BoxDecoration(
borderRadius: BorderRadius.only(
topLeft: Radius.circular(20),
topRight: Radius.circular(20),
),
color: Colors.black),
),
)
]),
));
}
}
// CircleAvatar(
// radius: 30,
// backgroundColor: Colors.white,
// child: Icon(
// Icons.list,
// color: Colors.blueAccent,
// size: 30,
// ),
// )
tasks_list.dart
import 'package:flutter/material.dart';
import 'package:learnon/screens/tasksscreennew.dart';
import 'package:learnon/widgets/task_tile.dart';
import 'package:provider/provider.dart';
import 'package:learnon/models/tasks_data.dart';
import 'dart:core';
class TasksList extends StatefulWidget {
#override
State<TasksList> createState() => _TasksListState();
}
class _TasksListState extends State<TasksList> {
#override
Widget build(BuildContext context) {
return Consumer<TaskData>(
builder: (context, taskData, child) {
return ListView.builder(
itemBuilder: (context, index) {
return TaskTile(
taskTitle: taskData.tasks[index].name,
isChecked: taskData.tasks[index].isDone,
timeLeft: taskData.tasks[index].date!
.difference(DateTime.now())
.inMinutes >
0
? ('${taskData.tasks[index].date!.difference(DateTime.now()).inHours.toString()} Hours left')
: 'Time Expired',
checkboxCallback: (checkBoxState) {
taskData.updateTask(taskData.tasks[index]);
},
longPressCallback: () {
if ((taskData.tasks[index].id!) != 0 ||
(taskData.tasks[index].id!) != 1) {
flutterLocalNotificationsPlugin
.cancel(taskData.tasks[index].id!);
flutterLocalNotificationsPlugin
.cancel(taskData.tasks[index].id! + 1);
}
taskData.deleteTask(taskData.tasks[index]);
},
notificationCallback: () {
flutterLocalNotificationsPlugin
.cancel(taskData.tasks[index].id!);
flutterLocalNotificationsPlugin
.cancel(taskData.tasks[index].id! + 1);
},
);
},
itemCount: taskData.taskCount,
);
},
);
}
}
task_tile.dart
import 'package:flutter/material.dart';
class TaskTile extends StatelessWidget {
final bool? isChecked;
final String? taskTitle;
final Function? checkboxCallback;
final Function longPressCallback;
final Function notificationCallback;
final String? timeLeft;
TaskTile(
{this.isChecked = false,
this.taskTitle,
this.checkboxCallback,
required this.longPressCallback,
this.timeLeft,
required this.notificationCallback()});
#override
Widget build(BuildContext context) {
return ListTile(
onLongPress: () {
longPressCallback();
},
title: Text(
taskTitle!,
style: TextStyle(
fontSize: 20,
color: (timeLeft!) == 'Time Expired'
? Colors.red
: isChecked!
? Colors.green
: null,
),
),
subtitle: Text(
isChecked! ? 'Completed' : (timeLeft!),
style: TextStyle(
color: (timeLeft!) == 'Time Expired'
? Colors.red
: isChecked!
? Colors.green
: null,
),
),
trailing: Checkbox(
activeColor: Colors.lightBlueAccent,
value: isChecked,
onChanged: (value) {
if (value == true) {
notificationCallback();
}
checkboxCallback!(value);
},
),
);
}
}
addtaskscreen.dart
// ignore_for_file: deprecated_member_use
import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import 'package:learnon/models/tasks_data.dart';
import 'package:date_field/date_field.dart';
import 'package:learnon/screens/tasksscreennew.dart';
import 'package:flutter_local_notifications/flutter_local_notifications.dart';
String? newTaskTitle;
DateTime? dateTime;
class AddTaskScreen extends StatelessWidget {
#override
Widget build(BuildContext context) {
return ChangeNotifierProvider<TaskData>(
create: (_) => TaskData(),
builder: (context, __) => Container(
height: MediaQuery.of(context).viewInsets.bottom + 300,
color: Colors.black,
child: Container(
height: MediaQuery.of(context).viewInsets.bottom + 300,
child: Padding(
padding: const EdgeInsets.symmetric(
horizontal: 50, vertical: 30),
child: Column(
crossAxisAlignment: CrossAxisAlignment.stretch,
children: [
Text(
'Task hinzufügen',
textAlign: TextAlign.center,
style: TextStyle(color: Colors.white, fontSize: 25),
),
TextField(
// controller: myController,
autofocus: true,
textAlign: TextAlign.center,
onChanged: (value) {
newTaskTitle = value;
},
),
SizedBox(
height: 10,
),
Text(
'Abgabedatum',
textAlign: TextAlign.center,
style: TextStyle(color: Colors.white, fontSize: 25),
),
SizedBox(
height: 10,
),
DateTimeFormField(
decoration: const InputDecoration(
hintStyle: TextStyle(color: null),
errorStyle: TextStyle(color: Colors.redAccent),
border: OutlineInputBorder(),
suffixIcon: Icon(Icons.event_note),
),
mode: DateTimeFieldPickerMode.dateAndTime,
initialDatePickerMode: DatePickerMode.day,
firstDate: DateTime.now(),
autovalidateMode: AutovalidateMode.always,
validator: (e) => (e?.day ?? 0) == 1
? 'Please not the first day'
: null,
onDateSelected: (DateTime value) {
dateTime = value;
},
),
TextButton(
style: ButtonStyle(
backgroundColor:
MaterialStateProperty.all(Colors.green),
),
autofocus: false,
onPressed: () async {
print(newTaskTitle);
print(dateTime);
Provider.of<TaskData>(context, listen: false)
.addTask(newTaskTitle!, dateTime!, id);
await flutterLocalNotificationsPlugin.schedule(
id++,
'Zeit abgelaufen',
newTaskTitle!,
dateTime!,
const NotificationDetails(
android: AndroidNotificationDetails(
'1', 'Zeit abgelaufen')),
androidAllowWhileIdle: true,
);
await flutterLocalNotificationsPlugin.schedule(
id++,
dateTime!.difference(DateTime.now()).inMinutes /
2 <
60
? '${dateTime!.difference(DateTime.now()).inMinutes / 2} Minuten übrig'
: '${dateTime!.difference(DateTime.now()).inHours / 2} Stunden übrig',
newTaskTitle!,
dateTime!.subtract(Duration(
minutes: dateTime!
.difference(DateTime.now())
.inMinutes ~/
2)),
const NotificationDetails(
android: AndroidNotificationDetails(
'5', 'Reminder')),
androidAllowWhileIdle: true,
);
Navigator.pop(context);
},
child: Text(
'Hinzufügen',
style: TextStyle(
color: Colors.white,
// backgroundColor: Colors.lightBlueAccent,
fontSize: 20,
),
),
)
],
),
),
decoration: BoxDecoration(
color: Colors.black,
borderRadius: BorderRadius.only(
topLeft: Radius.circular(20),
topRight: Radius.circular(20),
),
)),
));
}
}

Answer 1

Since you're making your TaskData as a **ChangeNotifier, are you wrapping your widget inside a Consumer widget, and using this class inside the Consumer widget, like this:
Consumer<TaskData>(
builder: (context, taskData, child) {
return <YOUR_WIDGET_HERE>;
}
)
That way all changes you make via your service class should be reflected and trigger a rebuild on your widget?
Also are you using a MultiProvider widget, how are you providing this class?