ClassCastException: SimpleTimeZone to ZoneInfo in readObject

Question

Hello
I have a java application running on weblogic.
Java version - 1.6.0_17-b04
And a client application written in Java as well (same version).
There are objects with GregorianCalendar which are transfered from server to client via RMI.
I occasionally get the following error:
Caused by: java.lang.ClassCastException: java.util.SimpleTimeZone cannot be cast to sun.util.calendar.ZoneInfo
at java.util.Calendar$1.run(Unknown Source)
at java.util.Calendar$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.util.Calendar.readObject(Unknown Source)
at sun.reflect.GeneratedMethodAccessor23.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at java.io.ObjectStreamClass.invokeReadObject(Unknown Source)
at java.io.ObjectInputStream.readSerialData(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.defaultReadFields(Unknown Source)
at java.io.ObjectInputStream.readSerialData(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.defaultReadFields(Unknown Source)
at java.io.ObjectInputStream.readSerialData(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.defaultReadFields(Unknown Source)
at java.io.ObjectInputStream.readSerialData(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.defaultReadFields(Unknown Source)
at java.io.ObjectInputStream.readSerialData(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.defaultReadFields(Unknown Source)
at java.io.ObjectInputStream.readSerialData(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.readObject(Unknown Source)
at java.util.ArrayList.readObject(Unknown Source)
at sun.reflect.GeneratedMethodAccessor28.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
I see that the readObject of Calendar code is:
ZoneInfo zi = null;
     try {
         zi = AccessController.doPrivileged(
              new PrivilegedExceptionAction<ZoneInfo>() {
               public ZoneInfo run() throws Exception {
                   return (ZoneInfo) input.readObject();
              CalendarAccessControlContext.INSTANCE);
     } catch (PrivilegedActionException pae) {
         Exception e = pae.getException();
         if (!(e instanceof OptionalDataException)) {
          if (e instanceof RuntimeException) {
              throw (RuntimeException) e;
          } else if (e instanceof IOException) {
              throw (IOException) e;
          } else if (e instanceof ClassNotFoundException) {
              throw (ClassNotFoundException) e;
          throw new RuntimeException(e);
     if (zi != null) {
         zone = zi;
     // If the deserialized object has a SimpleTimeZone, try to
     // replace it with a ZoneInfo equivalent (as of 1.4) in order
     // to be compatible with the SimpleTimeZone-based
     // implementation as much as possible.
     if (zone instanceof SimpleTimeZone) {
         String id = zone.getID();
         TimeZone tz = TimeZone.getTimeZone(id);
         if (tz != null && tz.hasSameRules(zone) && tz.getID().equals(id)) {
          zone = tz;
     }There is casting to ZoneInfo no matter what's the class is actually instance of.
In my case, the calendar sometimes contains SimpleTimeZone and not ZoneInfo which causes for the ClassCastException.
I also find that there are occasions where the zone variable holds SimpleTimeZone (gets to the line "if (zone instanceof SimpleTimeZone)" and equals true) but doesn't fail in "return (ZoneInfo) input.readObject();".
Any idea?

Answer 1

Yeah, they changed the default timezone's type between JDKs (or something along those lines) and it's breaking up some things.
Some more info [here.|http://www.coderanch.com/t/496765/java/java/ClassCastException-during-SimpleTimeZone-ZoneInfo-conversion]