I cant even print a nullable value - flutter

Question

basically the problem is clear :
here is my code :
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
class AddTaskScreen extends StatelessWidget {
#override
Widget build(BuildContext context) {
late String newTaskTitle;
return Container(
color: Color(0xFF757575),
child: Container(
padding: EdgeInsets.all(20),
decoration: BoxDecoration(
color: Colors.limeAccent[400],
borderRadius: BorderRadius.only(
topLeft: Radius.circular(60),
topRight: Radius.circular(60),
),
),
child: Column(
crossAxisAlignment: CrossAxisAlignment.stretch,
children: [
Text(
'Add Task',
textAlign: TextAlign.center,
style: TextStyle(fontSize: 30, color: Colors.brown[900]),
),
SizedBox(
height: 12,
),
TextField(
onChanged: (newText) {
newTaskTitle = newText;
},
autocorrect: false,
decoration: InputDecoration(
enabledBorder: OutlineInputBorder(
borderSide: BorderSide(
color: Colors.brown[800]!,
width: 2,
),
borderRadius: BorderRadius.circular(30),
),
hintText: 'Type Your Task ...',
labelStyle: TextStyle(
color: Colors.green[900],
),
helperStyle: TextStyle(
color: Colors.brown[900],
),
focusedBorder: OutlineInputBorder(
borderRadius: BorderRadius.circular(60),
borderSide: BorderSide(
color: Colors.brown[900]!,
width: 2,
),
),
),
),
SizedBox(
height: 12,
),
ElevatedButton(
onPressed: () {
// Provider.of<TaskData>(context, listen: false)
// .addTask(newTaskTitle);
// Navigator.pop(context);
print(newTaskTitle);
// Provider.of<TaskData>(context, listen: false)
// .addTask(newTaskTitle);
// Navigator.pop(context);
},
child: Text(
'Add',
style: TextStyle(color: Colors.brown[900]),
),
style: ButtonStyle(
backgroundColor: MaterialStateColor.resolveWith(
(states) => Colors.lightGreen),
elevation: MaterialStateProperty.resolveWith((states) => 6),
shadowColor:
MaterialStateColor.resolveWith((states) => Colors.green),
minimumSize: MaterialStateProperty.resolveWith(
(states) => Size.square(40.67)),
),
),
],
),
),
);
}
}
please help me ...at this stage I just want to print the value that the user enters in the text field in the console ...but it gives me error :
LateInitializationError: Local 'newTaskTitle' has not been initialized.
i have also changed it to a stateful widget to check if it works with setstate but it didnt ..
i also made it nullable like this => String? newTaskTitle; and Ofcourse it made to change a lot of things but at last the null value was passed ...there is a problem whithin the onChange callback of the textfield that doesnt assign the new value of user input to the variable i have created ...
How can I fixe this problem ?

Answer 1

change
late String newTaskTitle;
to
ValueNotifier<String> newTaskTitle = ValueNotifier("");
and put ElevatedButton inside ValueListenableBuilder
like this
ValueListenableBuilder<String>(
listenable : newTaskTitle,
builder : (ctx,taskt,_){
return ElevatedButton(
onPressed : taskt.isEmpty ? null : (){
// put you logic
}
.....
);
}
);
change onChanged of textField like this
onChanged: (newText) {
newTaskTitle.value = newText;
},