Convert DateTime to Date, but TimeZone is missing?

A code snippet to use Joda Time to convert a java.util.Date to different timezone :

//java.util.Date : 22-1-2015 10:15:55 AM
//System TimeZone : Asia/Singapore
//Convert java.util.Date to America/New_York TimeZone
DateTime dt = new DateTime(date);
DateTimeZone dtZone = DateTimeZone.forID("America/New_York");
DateTime dtus = dt.withZone(dtZone); //21-1-2015 09:15:55 PM - Correct!
//Convert Joda DateTime back to java.util.Date, and print it out
Date dateInUS = dtus.toDate();
System.out.println(dateInUS); //22-1-2015 10:15:55 AM - What???Why???

The problem is, if you convert back the Joda DateTime to java.util.Date, the timezone will revert back to system default TimeZone!?

Solution

In Java, java.util.Date doesn’t know about timezone, If a java.util.Date is printed with toString(), it will always print the date with system default TimeZone.

To fix it, convert DateTime to Joda LocalDateTime first.

DateTime dt = new DateTime(date);
DateTimeZone dtZone = DateTimeZone.forID("America/New_York");
DateTime dtus = dt.withZone(dtZone); //21-1-2015 09:15:55 PM - Correct!
Date dateInUS = dtus.toLocalDateTime().toDate();
System.out.println(dateInUS); //21-1-2015 09:15:55 PM - Correct!