Retrieve date earlier than the specified date. The returned date should
be adjusted to the beginning of the time period. For example, if the
time period is in weeks and begins on Sunday, and the input date is
Thursday, February 19, 2009, then the adjusted date should be
Sunday, February 15, 2009.
date - time to be adjusted
the adjusted time
java.util.Date getNextDate(java.util.Date date)
Retrieve date after the specified date. For example, if the time period
is in weeks, and the input date is Sunday, February 15, 2009, then the
returned date should be Sunday, February 22, 2009.