Date in Java

How to add days to a particular date (say 8/31/2007) in Java? I am
aware of DATE and CALENDAR Objects in Java but not sure about methods.

Date Arithmetic function. Adds the specified (signed) amount of time
to the given time field, based on the calendar's rules. For example,
to subtract 5 days from the current time of the calendar, you can
achieve it by calling:

add(Calendar.DATE, -5).

or to add 1 month to current date use this snippet

add(Calendar.MONTH,1)