how to compare showdatepicker + showtimepicker results with current date (datetime.now()) - flutter

Question

I can get the date time values with date and time picker. I want to combine the date and time values ​​I have obtained and compare them with the current date (DateTime.now() format).
How can I do it?
Future _selectDayAndTime(BuildContext context) async {
DateTime _selectedDay = await showDatePicker(
context: context,
initialDate: _date ?? DateTime.now(),
firstDate: DateTime(2020),
lastDate: DateTime(2100),
builder: (BuildContext context, Widget child) => child
);
TimeOfDay _selectedTime = await showTimePicker(
context: context,
initialTime: _time ?? TimeOfDay.now(),
);
if(_selectedDay != null && _selectedTime != null) {
setState(() {
_date = _selectedDay;
_time = _selectedTime;
});
debugPrint("Day result : $_date");
debugPrint("Time result : $_time");
}
}
Result
I/flutter ( 9596): Day result : 2020-01-16 00:00:00.000
I/flutter ( 9596): Time result : TimeOfDay(18:30)

Answer 1

TimeOfDay holds only hour and minutes. showDatePicker() returns a DateTime object, although it contains only year, month and day which are meaningful. You may update this DateTime object's hour and minutes with that of TimeofDay.
A vague code would as shown below.
var _date = _selectedDay;
var _time = _selectedTime;
var updatedDateTime = new DateTime(_date.year, _date.month, _date.day, _time.hour, _time.minute, _date.second);
And now, you can use standart DateTime class methods, to compare this updatedDateTime with DateTime.now().

Answer 2

This might help you :
var date = DateTime.now();
var time = TimeOfDay(hour: 12, minute: 00);
// Combined DateTime and TimeOfDay
var pickedTime = DateTime(date.year, date.month, date.day, time.hour, time.minute);
// returns -1 if pickedTime is before, 1 if after, 0 if equal.
var comparison = pickedTime.compareTo(date);
// time between now and the time of day.
var duration = Duration(milliseconds: date.millisecondsSinceEpoch - pickedTime.millisecondsSinceEpoch);