Archive for the ‘Java Programming’ tag
Java Gregorian Date
One of my students asked for an example of how to work with a Gregorian date and timezones in Java. I dug out an old example file from when I taught Java at Regis University.
The code follows:
/* || Program name: MyGregorian.java || Created by: Michael McLaughlin || Creation date: 10/07/02 || History: || ---------------------------------------------------------------------- || Date Author Purpose || -------- ---------------------- --------------------------------- || dd/mm/yy {Name} {Brief statement of change.} || ---------------------------------------------------------------------- || Execution method: Static class demonstrating timezone setting. || Program purpose: Designed as a stand alone program. */ // Class imports. import java.util.Calendar; import java.util.GregorianCalendar; import java.util.TimeZone; // Define MyGregorian class. public class MyGregorian { // Testing static main() method. public static void main(String args[]) { // Set an initial variable. String initial = ""; System.out.println("======================================================"); System.out.println("Value of [user.timezone]: [" + (initial = (null != System.getProperty("user.timezone")) ? "Unset" : System.getProperty("user.timezone")) + "]"); System.out.println("======================================================"); GregorianCalendar gc = (GregorianCalendar) Calendar.getInstance(); System.out.println("Calendar Date: [" + gc.getTime() + "]"); gc.add(GregorianCalendar.MONTH,1); System.out.println("Calendar Date: [" + gc.getTime() + "]"); System.out.println("======================================================"); System.out.println("Value of [user.timezone]: [" + System.getProperty("user.timezone") + "]"); System.out.println("Value of [user.timezone]: [" + System.setProperty("user.timezone","") + "]"); gc.add(GregorianCalendar.MONTH,1); System.out.println("Calendar Date: [" + gc.getTime() + "]"); System.out.println("======================================================"); Calendar c = Calendar.getInstance(); System.out.println("Calendar Date: [" + c.getTime() + "]"); // Move the date ahead one month, hour and minute. c.add(Calendar.MONTH,1); System.out.println("Calendar Date: [" + c.getTime() + "]"); System.out.println("======================================================"); } // End of testing static main() method. } // End of MyGregorian class. |
It prints to console:
====================================================== Value of [user.timezone]: [Unset] ====================================================== Calendar Date: [Thu May 05 23:43:42 MDT 2022] Calendar Date: [Sun Jun 05 23:43:42 MDT 2022] ====================================================== Value of [user.timezone]: [America/Denver] Value of [user.timezone]: [America/Denver] Calendar Date: [Tue Jul 05 23:43:42 MDT 2022] ====================================================== Calendar Date: [Thu May 05 23:43:42 MDT 2022] Calendar Date: [Sun Jun 05 23:43:42 MDT 2022] ====================================================== |
As always, I hope this helps those who need to see and example to work with Gregorian dates.