Reference

extends Object

java.lang.Object
↳	java.lang.ref.Reference<T>

Known Direct Subclasses

PhantomReference<T>, SoftReference<T>, WeakReference<T>

Known Indirect Subclasses

Cleaner

Class Overview

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.

Summary

Public Methods
void	clear() Clears this reference object.
boolean	enqueue() Adds this reference object to the queue with which it is registered, if any.
T	get() Returns this reference object's referent.
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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Inherited Methods

From class java.lang.Object

Object	clone() Creates and returns a copy of this object.
boolean	equals(Object obj) Indicates whether some other object is "equal to" this one.
void	finalize() Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
final Class<?>	getClass() Returns the runtime class of this `Object`.
int	hashCode() Returns a hash code value for the object.
final void	notify() Wakes up a single thread that is waiting on this object's monitor.
final void	notifyAll() Wakes up all threads that are waiting on this object's monitor.
String	toString() Returns a string representation of the object.
final void	wait() Causes the current thread to wait until another thread invokes the `notify()` method or the `notifyAll()` method for this object.
final void	wait(long timeout, int nanos) Causes the current thread to wait until another thread invokes the `notify()` method or the `notifyAll()` method for this object, or some other thread interrupts the current thread, or a certain amount of real time has elapsed.
final void	wait(long timeout) Causes the current thread to wait until either another thread invokes the `notify()` method or the `notifyAll()` method for this object, or a specified amount of time has elapsed.

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

Classes

Reference

Class Overview

Summary

Public Methods

public void clear ()

public boolean enqueue ()

Returns

public T get ()

Returns

public boolean isEnqueued ()

Returns