Late Initialization Error in Flutter because of _startDate - flutter

Question

As you can see in the included screenshot, I am getting a LateInitializationError upon running my app. The cause is in the code below, but I can't figure out how to fix it. It certainly has to do with the "late DateTime _startDate;" that I am using, but unsure what the right approach is. Do you have any idea? Thanks in advance for looking into it!
class AddEventPage extends StatefulWidget {
final DateTime? selectedDate;
final AppEvent? event;
const AddEventPage({Key? key, this.selectedDate, this.event})
: super(key: key);
#override
_AddEventPageState createState() => _AddEventPageState();
}
late DateTime _startDate;
late TimeOfDay _startTime;
late DateTime _endDate;
late TimeOfDay _endTime;
class _AddEventPageState extends State<AddEventPage> {
final _formKey = GlobalKey<FormBuilderState>();
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
backgroundColor: Colors.transparent,
leading: IconButton(
icon: Icon(
Icons.clear,
color: AppColors.primaryColor,
),
onPressed: () {
Navigator.pop(context);
},
),
actions: [
Padding(
padding: const EdgeInsets.all(8.0),
child: ElevatedButton(
onPressed: () async {
//save
_formKey.currentState!.save();
final data =
Map<String, dynamic>.from(_formKey.currentState!.value);
data["Time Start"] =
(data["Time Start"] as DateTime).millisecondsSinceEpoch;
if (widget.event != null) {
//update
await eventDBS.updateData(widget.event!.id!, data);
} else {
//create
await eventDBS.create({
...data,
"user_id": context.read(userRepoProvider).user!.id,
});
}
Navigator.pop(context);
},
child: Text("Save"),
),
)
],
),
body: ListView(
padding: const EdgeInsets.all(16.0),
children: <Widget>[
//add event form
FormBuilder(
key: _formKey,
child: Column(
children: [
FormBuilderTextField(
name: "title",
initialValue: widget.event?.title,
decoration: InputDecoration(
hintText: "Add Title",
border: InputBorder.none,
contentPadding: const EdgeInsets.only(left: 48.0)),
),
Divider(),
FormBuilderTextField(
name: "description",
initialValue: widget.event?.description,
minLines: 1,
maxLines: 5,
decoration: InputDecoration(
hintText: "Add Details",
border: InputBorder.none,
prefixIcon: Icon(Icons.short_text)),
),
Divider(),
FormBuilderSwitch(
name: "public",
initialValue: widget.event?.public ?? false,
title: Text("Public"),
controlAffinity: ListTileControlAffinity.leading,
decoration: InputDecoration(
border: InputBorder.none,
),
),
Divider(),
Neumorphic(
style: NeumorphicStyle(color: Colors.white),
child: Column(
children: [
GestureDetector(
child: Text(
DateFormat('EEE, MMM dd, yyyy')
.format(_startDate),
textAlign: TextAlign.left),
onTap: () async {
final DateTime? date = await showDatePicker(
context: context,
initialDate: _startDate,
firstDate: DateTime(2000),
lastDate: DateTime(2100),
);
if (date != null && date != _startDate) {
setState(() {
final Duration difference =
_endDate.difference(_startDate);
_startDate = DateTime(
date.year,
date.month,
date.day,
_startTime.hour,
_startTime.minute,
0);
_endDate = _startDate.add(difference);
_endTime = TimeOfDay(
hour: _endDate.hour,
minute: _endDate.minute);
});
}
}),
Container(
child: FormBuilderDateTimePicker(
name: "Time End",
initialValue: widget.selectedDate ??
widget.event?.date ??
DateTime.now(),
initialDate: DateTime.now(),
fieldHintText: "Add Date",
initialDatePickerMode: DatePickerMode.day,
inputType: InputType.both,
format: DateFormat('EEE, dd MMM, yyyy HH:mm'),
decoration: InputDecoration(
border: InputBorder.none,
prefix: Text(' '),
),
),
),
],
),
),
],
),
),
],
),
);
}
}

Answer 1

late to the keyword means that your property will be initialized when you use it for the first time.
You like to initialize like this:
late DateTime _startDate = DateTime.now();
And as well as change the others value respectively

Answer 2

In GestureDetector you are using a Text widget and passing the _startDate as value but you have not assigned any value to it beforehand, this causes this error, try giving it an initial value before using it.

Answer 3

You can use the following code as well :
DateTime? _startDate;

Answer 4

I have exactly problem.
Some objects should not be initialized directly, hence the creation of late.
For example I don't want to initialize a File object at creation, but afterwards I use late but flutter returns an error.strong text.
So run: flutter run --release