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
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Method Summary
Modifier and TypeMethodDescriptionvoidclear()Make the referent null.protected Objectclone()This method will always throw CloneNotSupportedException.booleanenqueue()Force the reference object to be enqueued if it has been associated with a queue.get()Return the referent of the reference object.booleanDeprecated.Use ReferenceQueue or Reference.refersTo(null).static voidreachabilityFence(Object ref) Used to keep the referenced object strongly reachable so that it is not reclaimable by garbage collection.final booleanDoes this object refer totarget?
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Method Details
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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.
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get
Return the referent of the reference object.- Returns:
- the referent to which reference refers, or null if object has been cleared.
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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.
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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
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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:
clonein classObject- Returns:
- Object a shallow copy of this object.
- Throws:
CloneNotSupportedException- always since a Reference cannot be cloned- Since:
- 11
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refersTo
Does this object refer totarget?- Parameters:
target- the candidate referent- Returns:
- true if this object refers to
target - Since:
- 16
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