What causes the slightly unpredictable ordering of the iterator() for the java.util.HashSet and HashMap.keySet() classes?

Question

Six years ago, I burned several days trying to hunt down where my perfectly deterministic framework was responding randomly. After meticulously chasing the entire framework

Answer 1

http://download.oracle.com/javase/1.4.2/docs/api/java/lang/Object.html#hashCode() says:

As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects. (This is typically implemented by converting the internal address of the object into an integer, but this implementation technique is not required by the JavaTM programming language.)

So maybe the internal address changes?

This also means that you could propably fix it without giving up speed by writing your own hashCode() method for everything that should act as a key.