Re: [xmlvm-users] GC of inner classes

[Paul P. <bay...@gm...>]

In Java, a *static* inner class is just a fancy way to make another class,
but a non-static inner class maintains an implied strong reference to the
containing instance.  In code, it is also available via
"ContainingClass.this".

For example, assume class A contains inner class B which contains inner
class C.  If B & C are static classes, they will not have access to the
containing class' non-static variables.  If B & C are NOT static, B
maintains a strong reference to A, and C maintains a strong reference to B.

In your scenario, A now has references to C, but has removed all references
to B.  As long as there is a non-collectible reference to A and as long as
A references C, B will not be collected, since C references B.

So to answer your questions directly:
1) Yes
2) The non-static inner class has a strong reference to the containing class

Thanks,
Paul

On Fri, Feb 24, 2012 at 7:31 AM, Panayotis Katsaloulis <
pan...@pa...> wrote:

> Is it possible to give me some hints, how the GC is working with inner
> classes?
>
> I have this scenario:
>
> A class (level 0) has an anonymous inner class (level 1) , which in turn
> has inside another anonymous inner class (level 2).
>
> The lifetime is like this:
>
> i) Class of level 0, creates a level 1 class
> ii) Level 1 class creates level 2 class and gives its reference back to
> level 0 class
> iii Level 0 class removes all usage & references of level 1 class (the
> item should be released)
> iv) Level 2 class starts executing, while requiring some variables of
> level 0 class.
>
> If I am correct, currently XMLVM is able to access information of level 0
> class to the level 2 class through the level 1 class.
> If this is so, a segmentation fault would appear.
>
>
> 1) Is this situation handled correctly by the C backend?
>
> 2) In ObjC backend, I can see that the inner classes hold a weak reference
> to the parent class. What if we establish a strong reference between the
> parent and the inner class ?
>
>
>
>
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