Re: a C usage I can't understand & "class variables"

[Jan Burse]

Dear All

The problem also arises for instance variables, it arises for fields in
general. In Java, the GC is freeing objects when they are not used
anymore. They are not used anymore if they are not reached by an
active processes anymore. To force reclaim of storage you can
agressively set fields to null. So you can do:

    a.p=null

and as well:

    a.pp=null

In case that there is no a.ppp pointing to the object that was formerly
behind a.p and a.pp the object gets automatically freeed. Otherwise
it stays. Probably a reason that Java has GC are security considerations.
You could spy out another application by falsely freeing storage and
peeking into it, or you can crash another and/or your own application
this way by poking into it.

Best Regards
--
Jan Burse                         EAWAG, SIAM CB-B33
Scheuchzerstr. 67                 Überlandstr. 133
8006 Zürich                       8600 Dübendorf
tel: +41-1-364 17 66              tel: +41-1-823 55 34




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