Static reference

[Yosi Hendarsjah]

Hi ranchers,

If a class A has a static reference to an object B, Will object B be garbage-collected? When?

[Jeroen Wenting]

oops, misread

Whether a reference is static or not doesn't matter.
Your B has a reference pointing to it so its reference count is larger than 0.
Therefore it won't be elligible for garbage collection.

As the reference is static is will never be garbage collected until the JVM goes down itself and cleans up the class object for A, unless some mechanism sets the reference to it to null.
[ June 02, 2004: Message edited by: Jeroen Wenting ]

[Rishi Tandon]

Yes, The reference of the Object B (Static member)can be garbage collected.

When :- Till the class is loaded Static members will be in memory.
once the class is about to be unloaded Static Members will be garbage collected.

[Peter den Haan]

But the question is, does the class ever get garbage collected?

The Java Language Specification, Sun set out the rules of engagement for class unloading. Classes loaded by the bootstrap classloader (Java core classes) never get unloaded. Other classes can unload if their classloader becomes unreachable. In practice, this will happen for instance in J2EE application servers with hot deploy.

- Peter

[Jeroen Wenting]

no, that's what I thought initially

The question is if an object to which a static reference exists can at some point be garbage collected.
The answer to that is a resounding "yes", namely the moment that reference is set to null

[Peter den Haan]

Originally posted by Jeroen Wenting:
The answer to that is a resounding "yes", namely the moment that reference is set to null

The moment you set the reference to null, the object ceases to be "an object to which a static reference exists".

Objects to which a static reference exists get garbage collected when their class gets garbage collected, which should happen only when their classloader becomes unreachable and available for garbage collection.

- Peter