FULL PRODUCT VERSION :
Java<TM> 2 Runtime Environment, Standard Edition <build 1.5.0_08-b03>
Java HotSpot<TM> Client VM <build 1.5.0_08-b03, mixed mode, sharing>

ADDITIONAL OS VERSION INFORMATION :
Microsoft Window XP [ version 5.1.2600 ]

A DESCRIPTION OF THE PROBLEM :
The code is be below:

public class test {
    public static void main(String[] args){
        try{
            GregorianCalendar gc1=new GregorianCalendar(1,0,1,0,0,0);
            gc1.set(Calendar.HOUR,13865672);
            System.out.println(gc1.getTime());
            
            GregorianCalendar gc2=new GregorianCalendar(1,0,1,0,0,0);
            gc2.set(Calendar.HOUR,13865696);
            System.out.println(gc2.getTime());

        }catch(Exception ex){ ex.printStackTrace();}
    }
}

The output of the above code is:

Thu Oct 04 08:00:00 CST 1582
Sun Oct 17 08:00:00 CST 1582
Press any key to continue...

We can see that:
13865696-13865672=24
Only one day. But first line output 04while the second line output 17.
Strange!

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
public class test {
    public static void main(String[] args){
        try{
            GregorianCalendar gc1=new GregorianCalendar(1,0,1,0,0,0);
            gc1.set(Calendar.HOUR,13865672);
            System.out.println(gc1.getTime());
            
            GregorianCalendar gc2=new GregorianCalendar(1,0,1,0,0,0);
            gc2.set(Calendar.HOUR,13865696);
            System.out.println(gc2.getTime());

        }catch(Exception ex){ ex.printStackTrace();}
    }
}

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Thu Oct 04 08:00:00 CST 1582
Fri Oct 05 08:00:00 CST 1582
Press any key to continue...
ACTUAL -
Thu Oct 04 08:00:00 CST 1582
Sun Oct 17 08:00:00 CST 1582
Press any key to continue...

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
public class test {
    public static void main(String[] args){
        try{
            GregorianCalendar gc1=new GregorianCalendar(1,0,1,0,0,0);
            gc1.set(Calendar.HOUR,13865672);
            System.out.println(gc1.getTime());
            
            GregorianCalendar gc2=new GregorianCalendar(1,0,1,0,0,0);
            gc2.set(Calendar.HOUR,13865696);
            System.out.println(gc2.getTime());

        }catch(Exception ex){ ex.printStackTrace();}
    }
}
---------- END SOURCE ----------