Dates

[Tim Eapen]

Hello everybody:

I am working through the Sierra/Bates SCJP book. Currently I am studying dates and have encountered something that is really bugging me. Here is some very simple code:

        Date d = new Date(1);
        
        Calendar cal = Calendar.getInstance();
        cal.setTime(d);
                
        System.out.println("Rolling the date...");        
 
        cal.roll(Calendar.MONTH, 2);
        System.out.println("Date: " + cal.getTime());
        
        cal.roll(Calendar.HOUR, 2);
        System.out.println("Date: " + cal.getTime());
        
        cal.roll(Calendar.SECOND, 6);
        System.out.println("Date: " + cal.getTime());
 

Here is the output for my JVM:

Date: Fri Feb 28 19:00:00 EST 1969
Date: Fri Feb 28 21:00:00 EST 1969
Date: Fri Feb 28 19:00:06 EST 1969

Notice that when I added 6 seconds, the hour field was rolled back two hours. I expect the last line to be: Date: Fri Feb 28 21:00:06 EST 1969.

Why does rolling the seconds field seem to affect the hour field? The JavaDoc states the following for the roll method:

Adds the specified (signed) amount to the specified calendar field without changing larger fields.

Since hour is a larger field than second, I expect rolling the seconds field to have no impact on the hour field. Am I missing something here?

Tim

[vitthal bywar]

This works fine on my JVM.
I tried
Calendar cal = Calendar.getInstance();
Date date = new Date(1);
cal.setTime(date);
System.out.println("Date1" + cal.getTime());
cal.roll(Calendar.MONTH, 2);
System.out.println("Date2" + cal.getTime());
cal.roll(Calendar.HOUR, 2);
System.out.println("Date3" + cal.getTime());
cal.roll(Calendar.SECOND, 6);
System.out.println("Date4" + cal.getTime());

And output was
Date1Thu Jan 01 05:30:00 IST 1970
Date2Sun Mar 01 05:30:00 IST 1970
Date3Sun Mar 01 07:30:00 IST 1970
Date4Sun Mar 01 07:30:06 IST 1970

[Anthony Karta]

Doesn't work on mine. strange stuff.

[Tim Eapen]

This is bizarre - I get the expected output at work. On my workstation I have Java 1.4.2. At home I have Java 1.5. Could that be the issue?

Tim

[Burkhard Hassel]

Hi all,


I see this bug with JDK1.5 if I compile with -source 1.4 or 1.5

Bu.