Known Direct Subclasses
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Abstract base class for reference objects. This class defines the operations common to all reference objects. Because reference objects are implemented in close cooperation with the garbage collector, this class may not be subclassed directly.
Public Method Summary
void |
clear()
Clears this reference object.
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boolean |
enqueue()
Adds this reference object to the queue with which it is registered,
if any.
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T |
get()
Returns this reference object's referent.
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boolean |
isEnqueued()
Tells whether or not this reference object has been enqueued, either by
the program or by the garbage collector.
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Protected Method Summary
void |
finalize()
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Inherited Method Summary
Public Methods
public void clear ()
Clears this reference object. Invoking this method will not cause this object to be enqueued.
This method is invoked only by Java code; when the garbage collector clears references it does so directly, without invoking this method.
public boolean enqueue ()
Adds this reference object to the queue with which it is registered, if any.
This method is invoked only by Java code; when the garbage collector enqueues references it does so directly, without invoking this method.
Returns
true
if this reference object was successfully enqueued;false
if it was already enqueued or if it was not registered with a queue when it was created
public T get ()
Returns this reference object's referent. If this reference object has
been cleared, either by the program or by the garbage collector, then
this method returns null
.
Returns
- The object to which this reference refers, or
null
if this reference object has been cleared
public boolean isEnqueued ()
Tells whether or not this reference object has been enqueued, either by
the program or by the garbage collector. If this reference object was
not registered with a queue when it was created, then this method will
always return false
.
Returns
true
if and only if this reference object has been enqueued