How to increment DateTime.now in dart

Question

I am trying to use the DatePicker in flutter and I want to set the initialDate to DateTime.now() and the lastDate I want to set to DateTime.now() + 20yrs so it increments the year dynamically. Current I have my lastDate set to the year (2100), but this would cause a problem when the year 2101 reaches. So how can I modify my function to increase the lastDate dynamically?

Here is my function:

DateTime _date = DateTime.now();

Future < Null > _checkInDate(BuildContext contex) async {
  DateTime ? _datePicker = await showDatePicker(
    context: context,
    builder: (BuildContext context, Widget ? child) {
      return Theme(
        data: ThemeData(
          primaryColor: Color(0xFFEF5350),
          colorScheme: ColorScheme.fromSwatch(primarySwatch: Colors.red)
          .copyWith(secondary: Color(0xFFFFF176)),
        ),
        child: child ? ? Text(""),
      );
    },
    initialDate: _date,
    firstDate: DateTime.now(),
    lastDate: DateTime(2100), //how can i increase the lastDate dynamically?
  );
  if (_datePicker != null && _datePicker != _date) {
    _checkInController.text = DateFormat('dd-MM-yyyy').format(_datePicker);
  }
}

Solution

Yes you can, use DateTime.now().year to get the current year and then add as many years as you want. Like this:

final date = DateTime(DateTime.now().year + 20);