/** The date at the end of the last century */
Date d1 = new GregorianCalendar(2000,11,31,23,59).getTime();
/** Today's date */
Date today = new Date();
// Get msec from each, and subtract.
long diff = today.getTime() - d1.getTime();
System.out.println("The 21st century (up to " + today +
") is " + (diff / (1000*60*60*24)) + " days old.");
