Bug 21483

Description Jared Burns 2002-07-11 09:25:40 EDT

This bug is related to Bug 12966.

1. Import the example classes from the J2ME Wireless Toolkit (WTK) found in 
$WTK_HOME/apps/demos/classes
2. Place a method entry breakpoint on a method in the 
example.manyballs.ManyBalls class.
3. Launch the J2ME WTK gray phone emulator with the "ManyBalls" example 
with the following commandline and attach with a remote java launch config:
emulator -Xdebug -Xdevice:DefaultGrayPhone -classpath
../apps/demos/classes:../lib/midpapi.zip
-Xrunjdwp:transport=dt_socket,address=8000,server=y 
example.manyballs.ManyBalls
4. The following exception occurs:
java.lang.InternalError: Got event of unknown type
at 
org.eclipse.jdi.internal.request.EventRequestManagerImpl.findRequest(EventRe
questManagerImpl.java:498)
at org.eclipse.jdi.internal.event.EventImpl.read(EventImpl.java:153)
at org.eclipse.jdi.internal.event.EventSetImpl.read(EventSetImpl.java:147)
at 
org.eclipse.jdi.internal.event.EventQueueImpl.remove(EventQueueImpl.java:59)
at 
org.eclipse.jdi.internal.event.EventQueueImpl.remove(EventQueueImpl.java:42)
at 
org.eclipse.jdt.internal.debug.core.EventDispatcher.run(EventDispatcher.java
:194)
at java.lang.Thread.run(Thread.java:536)

This exception is thrown while receiving the class prepare event for the
ManyBalls class. The error message here is misleading. The problem isn't 
really an unknown event type, it's the fact that the ClassPrepareEvent is 
coming to us from the VM with a status of VERIFIED instead of PREPARED. Our 
ClassPrepareEventImpl.read(...) method says:
if ((event.fStatus & ReferenceTypeImpl.JDWP_CLASS_STATUS_PREPARED) == 0)
  return null;
EventImpl.read(...) gets this null result from the ClassPrepareEventImpl 
and passes it into EventRequestManagerImpl.findRequest(...) where the 
exception is thrown.

There are at least three things to look at here:
Why does the VM give us a ClassPrepareEvent for an unprepared class?
Why do we return null from ClassPrepareEventImpl when we get a class status 
other than what we expect?
Why do we return null from ClassPrepareEventImpl but not handle null in 
EventImpl.read(...)?