- java.lang.Object
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- java.lang.ref.Reference<T>
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- Direct Known Subclasses:
PhantomReference
,SoftReference
,WeakReference
public abstract class Reference<T> extends Object
Abstract class which describes behavior common to all reference objects.- Since:
- 1.2
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description void
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.T
get()
Return the referent of the reference object.boolean
isEnqueued()
Return whether the reference object has been enqueued.static void
reachabilityFence(Object ref)
Used to keep the referenced object strongly reachable so that it is not reclaimable by garbage collection.
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Method Detail
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clear
public void clear()
Make the referent null. This does not force the reference object to be enqueued.
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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
public T 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
public boolean isEnqueued()
Return whether the reference object has been enqueued.- Returns:
- true if Reference has been enqueued, false otherwise.
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reachabilityFence
public static void reachabilityFence(Object ref)
Used to keep the referenced object strongly reachable so that it is not reclaimable by garbage collection.- Parameters:
ref
- reference of the object.- Since:
- 1.9
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clone
protected Object clone() throws CloneNotSupportedException
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
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