| Package | Description | 
|---|---|
| java.lang.ref | 
 Provides reference-object classes, which support a limited degree of
interaction with the garbage collector. 
 | 
| Modifier and Type | Class and Description | 
|---|---|
class  | 
PhantomReference<T>
Phantom reference objects, which are enqueued after the collector
 determines that their referents may otherwise be reclaimed. 
 | 
class  | 
SoftReference<T>
Soft reference objects, which are cleared at the discretion of the garbage
 collector in response to memory demand. 
 | 
class  | 
WeakReference<T>
Weak reference objects, which do not prevent their referents from being
 made finalizable, finalized, and then reclaimed. 
 | 
| Modifier and Type | Method and Description | 
|---|---|
Reference<? extends T> | 
ReferenceQueue.poll()
Polls this queue to see if a reference object is available. 
 | 
Reference<? extends T> | 
ReferenceQueue.remove()
Removes the next reference object in this queue, blocking until one
 becomes available. 
 | 
Reference<? extends T> | 
ReferenceQueue.remove(long timeout)
Removes the next reference object in this queue, blocking until either
 one becomes available or the given timeout period expires. 
 | 
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