FULL PRODUCT VERSION :
java version "1.5.0-rc"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0-rc-b63)
Java HotSpot(TM) Client VM (build 1.5.0-rc-b63, mixed mode, sharing)

A DESCRIPTION OF THE PROBLEM :
Setting the 'HOUR' field of a freshly created GregorianCalendar has no effect on the Date value returned by a subsequent call to getTime().
You have to call getTime() at least once before setting the 'HOUR' field to make it work.
There is no problem with setting the 'HOUR_OF_DAY' field

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Compile and run the test code under jdk 1.5 , watch the output to stdout.

It does work in prior releases of the VM (at least up to 1.4.2_04)

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Date: Thu Jan 01 01:00:00 CET 2004

ACTUAL -
Date: Thu Jan 01 00:00:00 CET 2004


REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.util.*;

public class CalTest {
   public CalTest() {}

   public static void main(String[] args) {
      GregorianCalendar cal = new GregorianCalendar(2004, 0,1);
//      activating this line makes it work!
//      cal.getTime();
      cal.set(Calendar.HOUR, 1);
      System.out.println("Date: " + cal.getTime());
   }
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Call getTime() in advance or use HOUR_OF_DAY instead.

Release Regression From : 1.4.2
The above release value was the last known release where this 
bug was known to work. Since then there has been a regression.
###@###.### 10/12/04 21:56 GMT