Re: When will finalize() be invoked?

From:

Lew <noone@lewscanon.com>

Newsgroups:

comp.lang.java.help

Date:

Sun, 21 Dec 2008 13:46:44 -0500

Message-ID:

<gim2uk$8bq$1@news.albasani.net>

Nguyen Minh Hai wrote:

I think the method finalize() of an unreferenced object will be
invoked only when the garbage collector runs, right?

Eric Sosman wrote:

Yes -- and no.

When the garbage collector discovers that an object instance
is garbage, it will arrange for the object's finalize() method
to be called. The actual call to finalize() might not happen
right away, though: It might be postponed to some later time.
If the JVM exits before the "later time," the finalize() method
might not be called at all.

OP - consider reading the Java Language Specification (JLS) for independence
in finding such information:
<http://java.sun.com/docs/books/jls/third_edition/html/execution.html#44748>

The Java programming language does not specify how soon a finalizer will be
invoked, except to say that it will happen before the storage for the object
is reused. Also, the language does not specify which thread will invoke the
finalizer for any given object.

Eric Sosman wrote:

Also, the JVM might not bother to call a "trivial" finalize().

Again, from the JLS:

For efficiency, an implementation may keep track of classes that do not
override the finalize method of class Object, or override it in a trivial
way, such as:

    protected void finalize() throws Throwable {
            super.finalize();
    }

We encourage implementations to treat such objects as having a finalizer
that is not overridden, and to finalize them more efficiently,
as described in ?12.6.1.

Eric Sosman wrote:

Finally, the code in a class could call finalize() at any
time, just as it could call any other protected method. This,
of course, would be a Very Bad Idea.

--
Lew