java.lang.ref

Class PhantomReference<T>

java.lang.Object

java.lang.ref.Reference<T>

java.lang.ref.PhantomReference<T>

public class PhantomReference<T>
extends Reference<T>

A phantom reference is useful, to get notified, when an object got finalized. You can't access that object though, since it is finalized. This is the reason, why get() always returns null.

Constructor Summary

Constructors

Constructor and Description
PhantomReference(T referent, ReferenceQueue<? super T> q) Creates a new phantom reference.

Method Summary

Methods

Modifier and Type	Method and Description
T	get() Returns the object, this reference refers to.

Methods inherited from class java.lang.ref.Reference

clear, enqueue, isEnqueued

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

PhantomReference

public PhantomReference(T referent,
                ReferenceQueue<? super T> q)

Creates a new phantom reference.

Parameters:

referent - the object that should be watched.

q - the queue that should be notified, if the referent was finalized. This mustn't be null.

Throws:

NullPointerException - if q is null.

Method Detail

get

public T get()

Returns the object, this reference refers to.

Overrides:

get in class Reference<T>

Returns:

null, since the refered object may be finalized and thus not accessible.