If Java's garbage collector moves objects, what is Object.hashCode and System.identityHashCode?

Question

I\'ve often heard that these methods (Object.hashCode and System.identityHashCode) return the address of the object, or something computed quickly from

Answer 1

The identityHashCode does not change for an object. So any moving is done beneath that level.

A rudimentary implementation would have a logical address --> physical address mapping for every object.

More sophisticated implementations would only have the mapping at a page level, so perhaps the last 6 bits is the memory offset, and the rest are the page id. The indirection would happen at the page id --> actual page address level.