Why would you ever implement finalize()?

Question

I\'ve been reading through a lot of the rookie Java questions on finalize() and find it kind of bewildering that no one has really made it plain that finalize()

Answer 1

Personally, I almost never used finalize() except in one rare circumstance: I made a custom generic-type collection, and I wrote a custom finalize() method that does the following:

public void finalize() throws Throwable {
    super.finalize();
    if (destructiveFinalize) {
        T item;
        for (int i = 0, l = length(); i < l; i++) {
            item = get(i);
            if (item == null) {
                continue;
            }
            if (item instanceof Window) {
                ((Window) get(i)).dispose();
            }
            if (item instanceof CompleteObject) {
                ((CompleteObject) get(i)).finalize();
            }
            set(i, null);
        }
    }
}

^{(CompleteObject is an interface I made that lets you specify that you've implemented rarely-implemented Object methods like #finalize(), #hashCode(), and #clone())}

So, using a sister #setDestructivelyFinalizes(boolean) method, the program using my collection can (help) guarantee that destroying a reference to this collection also destroys references to its contents and disposes any windows that might keep the JVM alive unintentionally. I considered also stopping any threads, but that opened a whole new can of worms.