Classes
| PhantomReference<T> | Phantom reference objects, which are enqueued after the collector determines that their referents may otherwise be reclaimed. |
| Reference<T> | Abstract base class for reference objects. |
| ReferenceQueue<T> | Reference queues, to which registered reference objects are appended by the garbage collector after the appropriate reachability changes are detected. |
| SoftReference<T> | Soft reference objects, which are cleared at the discretion of the garbage collector in response to memory demand. |
| WeakReference<T> | Weak reference objects, which do not prevent their referents from being made finalizable, finalized, and then reclaimed. |