java.util.Date - Deleting three months from a date?

Question

I have a date of type java.util.Date

I want to subtract three months from it.

Not finding a lot of joy in the API.

Answer 1

    Calendar cal = Calendar.getInstance();
 cal.setTime(new Date());
 cal.add(Calendar.MONTH, -3);

set your date using setTime method.

Answer 2

The Date class itself isn't enough (+: You've got to use the Calendar class here

Something along these lines

GregorianCalendar lCalendar = new GregorianCalendar();
lCalendar.setTime( aDate );
lCalendar.add(Calendar.MONTH, -3);

p.s. the snippet above is not tested to be compilable.

Answer 3

Here's the plain JDK version, it needs the Calendar class as a helper:

Calendar c = Calendar.getInstance(); 
c.setTime(new Date()); 
c.add(Calendar.MONTH, -3);
return c.getTime();

But you should seriously consider using the Joda library, because of various shortcomings of the Date and Calendar classes. With Joda you can do the following:

return new DateTime().minusMonths(3).toDate();

Or if you want to subtract from a given date instead of the current:

return new DateTime(referenceDate).minusMonths(3).toDate();

Answer 4

I always recommend Joda for this sort of stuff. It has a much nicer API, and doesn't suffer from threading issues that the standard Java date/time has (e.g. issues with SimpleDateFormat, or general mutability).

e.g.

DateTime result = dt.minusMonths(3);