Java 3D exception: TransformGroupRetained : Can't find hashKey

Following exception appears in my Java 3D application:

TransformGroupRetained : Can't find hashKey
Exception in thread "J3D-TransformStructureUpdateThread-1" java.lang.ArrayIndexOutOfBoundsException: -1
 at javax.media.j3d.TransformGroupRetained.updateChildLocalToVworld(TransformGroupRetained.java:979)
 at javax.media.j3d.TransformGroupRetained.updateChildLocalToVworld(TransformGroupRetained.java:961)
 at javax.media.j3d.TransformGroupRetained.processChildLocalToVworld(TransformGroupRetained.java:825)
 at javax.media.j3d.TransformStructure.processCurrentLocalToVworld(TransformStructure.java:306)
 at javax.media.j3d.TransformStructure.processMessages(TransformStructure.java:186)
 at javax.media.j3d.StructureUpdateThread.doWork(StructureUpdateThread.java:83)
 at javax.media.j3d.J3dThread.run(J3dThread.java:250)

In my case I incorrectly used one of available ways to hide and show part of 3D objects graph. I use javax.media.j3d.Link and when I wand to show specific subgraph I call:

link.setSharedGroup(mySharedGroup);

and similary I called when I want to hide some object I called:

link.setSharedGroup(null);

I works fine up to the moment when setSharedGroup was called with same object parameter more than once. It leads to "TransformGroupRetained : Can't find hashKey" Exception. Fix is quite simple:

if(link.getSharedGroup() == null){
    link.setSharedGroup(mySharedGroup);
}

and

if(link.getSharedGroup() != null){
    link.setSharedGroup(null);
}

This should help. Hopefully it will save you some time.

regards