Garbage Collection Help

Question

My understanding of garbage collection is that resources utilized by an object are released when no reference to the object exist. I accomplish this by ensuring that all references to an unneeded object are null.
My question/concern is this. If I have an object "A" that has references to other objects "B", "C", and "D", will the all objects be elibible for garbage collection when the reference to object A is set to null? I suspect that objects "B", "C", and "D" persist until the virtual machine is terminated.
Is the practice of creating a method within a class to make all inner objects eligible for garbage collection prior to setting the object reference to null. (i.e. set objects "B", "C", and "D" to null prior to setting "A" to null).
Maybe I am just paranoid??

Answer 1

My understanding of garbage collection is that
resources utilized by an object are released when no
reference to the object existThat's not correct. Objects can have references that point to them and still be garbage collected. For example:
Vector v = new Vector();
v.add(new Object());
v = null;
After this code is executed, the Vector object has a reference to the "new Object()" created. However, the Vector itself is not reachable, and therefore the "new Object()" is unreachable, and therefore both are collected.
The garbage collector collects unreachable objects.
I accomplish this by
ensuring that all references to an unneeded object are
null.It is quite rare that setting a reference to null is needed to make an object unreachable. Don't do it -- it makes your code slower, less readable, and harder to modify.
My question/concern is this. If I have an object "A"
that has references to other objects "B", "C", and
"D", will the all objects be elibible for garbage
collection when the reference to object A is set to
null? I suspect that objects "B", "C", and "D"
persist until the virtual machine is terminated.Yes -- all will be collected when A becomes unreachable. As noted earlier, you shouldn't need to set any reference to null for this to happen.
Is the practice of creating a method within a class to
make all inner objects eligible for garbage collection
prior to setting the object reference to null. (i.e.
set objects "B", "C", and "D" to null prior to setting
"A" to null).
Maybe I am just paranoid??Yes. Just let the garbage collector do its job and collect unreachable objects. You should almost never need to write any code to "help" the garbage collector.