Have you ever used PhantomReference in any project?

Question

The only thing I know about PhantomReference is,

• If you use its get() method, it will always return null

Answer 1

A general diced-up table explanation, from the Java Glossary.

Which of course coincides with the PhantomReference documentation:

Phantom reference objects, which are enqueued after the collector determines that their referents may otherwise be reclaimed. Phantom references are most often used for scheduling pre-mortem cleanup actions in a more flexible way than is possible with the Java finalization mechanism.

And last but not least, all the gory details (this is a good read): Java Reference Objects (or How I Learned to Stop Worrying and Love OutOfMemoryError).

Happy coding. (But to answer the question, I've only ever used WeakReferences.)