java.lang.Object
java.lang.ref.Reference<T>
- Direct Known Subclasses:
PhantomReference
,SoftReference
,WeakReference
Abstract class which describes behavior common to all reference objects.
- Since:
- 1.2
-
Method Summary
Modifier and TypeMethodDescriptionvoid
clear()
Make the referent null.protected Object
clone()
This method will always throw CloneNotSupportedException.boolean
enqueue()
Force the reference object to be enqueued if it has been associated with a queue.get()
Return the referent of the reference object.boolean
Deprecated.Use ReferenceQueue or Reference.refersTo(null).static void
reachabilityFence
(Object ref) Used to keep the referenced object strongly reachable so that it is not reclaimable by garbage collection.final boolean
Does this object refer totarget
?
-
Method Details
-
clear
public void clear()Make the referent null. This does not force the reference object to be enqueued. -
enqueue
public boolean enqueue()Force the reference object to be enqueued if it has been associated with a queue.- Returns:
- true if Reference is enqueued, false otherwise.
-
get
Return the referent of the reference object.- Returns:
- the referent to which reference refers, or null if object has been cleared.
-
isEnqueued
Deprecated.Use ReferenceQueue or Reference.refersTo(null).Return whether the reference object has been enqueued.- Returns:
- true if Reference has been enqueued, false otherwise.
-
reachabilityFence
Used to keep the referenced object strongly reachable so that it is not reclaimable by garbage collection.- Parameters:
ref
- reference of the object.- Since:
- 9
-
clone
This method will always throw CloneNotSupportedException. A clone of this instance will not be returned since a Reference cannot be cloned. Workaround is to create a new Reference.- Overrides:
clone
in classObject
- Returns:
- Object a shallow copy of this object.
- Throws:
CloneNotSupportedException
- always since a Reference cannot be cloned- Since:
- 11
-
refersTo
Does this object refer totarget
?- Parameters:
target
- the candidate referent- Returns:
- true if this object refers to
target
- Since:
- 16
-