Re: finalize called on an object that's still in scope?

Piotr Kobzda <>
Wed, 25 Apr 2007 03:38:15 +0200
Paul Tomblin wrote:

The local variable is not finalised. The object that was once referred
to by the local variable is (or may be) finalised. Scope doesn't
actually have anything to do with it at all.

But the local variable is still in scope, so therefore is still referring
to it. I would not expect the object to be garbage
collected/finalized/destructed and if it is, then there is something
seriously wrong happening here.

Nothing is wrong here. Each local lives (as a reference) in a local
stack frame space, which (space) is a subject to reuse whenever allowed
by language rules. So, the last use of a local (when it becomes
unreachable), is also a last time of guaranteed referencing of it from
the stack, and it's referenced usually as long as some next operation
replaces its stack space with another reference (in simple methods
though, it may not happen at all before method end).

See JLS3 12.6.1 for details on objects reachability, and what optimizing
transformations of a program are allowed.

Short quote:
"For example, a compiler or code generator may choose to set a variable
or parameter that will no longer be used to null to cause the storage
for such an object to be potentially reclaimable sooner."


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