Just curious, does it have to be GregorianCalendar or should you be using the generic Calendar class? Not that it truly matters to the answer, but it is shorter to just type "Calendar" and it more generic
To get the current date,
To get the date of one week ago:
To get the date two weeks hence:
(Note that you add three weeks, because we took one week away in the previous step. You could also get a new instance of the Calendar and add two weeks...this would produce more readable code, but is less efficient)
Once you have the start date and the end date, see
here to get the list of dates between the two.
You can then display the dates either using the .toString() method or, more likely, create a java.text.SimpleDateFormat to format the dates for you.