[859] in java-interest
Idem: memory deallocation
daemon@ATHENA.MIT.EDU (JD Brennan)
Fri Aug 11 20:00:07 1995
Date: Fri, 11 Aug 1995 09:59:10 -0700
From: JD Brennan <brennan@symbologic.com>
To: Francois Boussard <francois@coplanet.fr>
Cc: java-interest@java.sun.com
In-Reply-To: <17787890@toto.iv>
Reply-To: JD Brennan <brennan@symbologic.com>
There are no value semantics in Java. Everything is reference
semantics. So there are no objects allocated on the stack, so
no local objects. Althought tmp looks like a C/C++ stack-allocated
local variable, in Java it's a reference to a heap allocated object.
So you have a local reference to a heap allocated object, which can
easily be assigned to a global reference which now points the same
heap allocated object. The scope of the object hasn't changed. Just
the scope of the reference to it.
JD Brennan
[brennan@symbologic.com Symbologic Corp., Seattle, WA]
Francois Boussard writes:
> > Jonathan Fine (jfine@umich.edu)
> > Tue, 8 Aug 1995 16:05:20 -0400 (EDT)
> >
> > I was wondering how java does memory deallocation since, as far as I
> > know, there is no free() or delete library functions. In the example
> > below, what happens to the memory originally allocated to list?
> >
> > Is that memory automagically deallocated, or are there destructors or
> > library functions I am unaware of?
> >
> > Thanks.
> >
> > import browser.Applet;
> >
> > class Test extends Applet {
> > String list[] = { "lions", "tigers", "bears" };
> >
> > public void init() {
> > String tmp[] = new String[list.length+1];
> > System.arraycopy( list, 0, tmp, 0, list.length );
> > list = tmp;
> > list[3] = "foobar";
> >
>
> I am also interested by this point ! :
> I HOPE that when no pointers points to a memory object, the garbage
> free it.
> So, what i've understood is :
> - your first list {"lions"...} is freed cause theres is no more
> reference pointing to it.
>
> - the second list (from tmp) will still stay alive after end of init()
>
> - so, a local object (tmp) can in fact become global if a global
> reference points to it.
>
> Well, now I am not an expert in Java, but that what i've understood.
> Perhaps someone from java-team could confirm it ?
>
> Thanks, bye.
> - --
> __________________________________________________________________________
> Francois BOUSSARD
> CoPlaNet : 3 Rue J.Guesde . 92309 . Levallois
> francois@coplanet.fr
> __________________________________________________________________________
>
>
>
-
Note to Sun employees: this is an EXTERNAL mailing list!
Info: send 'help' to java-interest-request@java.sun.com
