63 lines
2.0 KiB
Java
63 lines
2.0 KiB
Java
/* java.lang.ref.PhantomReference
|
|
Copyright (C) 1999 Free Software Foundation, Inc.
|
|
|
|
This file is part of GNU Classpath.
|
|
|
|
GNU Classpath is free software; you can redistribute it and/or modify
|
|
it under the terms of the GNU General Public License as published by
|
|
the Free Software Foundation; either version 2, or (at your option)
|
|
any later version.
|
|
|
|
GNU Classpath is distributed in the hope that it will be useful, but
|
|
WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with GNU Classpath; see the file COPYING. If not, write to the
|
|
Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
|
|
02111-1307 USA.
|
|
|
|
As a special exception, if you link this library with other files to
|
|
produce an executable, this library does not by itself cause the
|
|
resulting executable to be covered by the GNU General Public License.
|
|
This exception does not however invalidate any other reasons why the
|
|
executable file might be covered by the GNU General Public License. */
|
|
|
|
|
|
package java.lang.ref;
|
|
|
|
/**
|
|
* 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 <code>get()</code> always
|
|
* returns null.
|
|
*
|
|
* @author Jochen Hoenicke
|
|
*/
|
|
public class PhantomReference
|
|
extends Reference
|
|
{
|
|
/**
|
|
* Creates a new phantom reference.
|
|
* @param referent the object that should be watched.
|
|
* @param q the queue that should be notified, if the referent was
|
|
* finalized. This mustn't be <code>null</code>.
|
|
* @exception NullPointerException if q is null.
|
|
*/
|
|
public PhantomReference(Object referent, ReferenceQueue q)
|
|
{
|
|
super(referent, q);
|
|
}
|
|
|
|
/**
|
|
* Returns the object, this reference refers to.
|
|
* @return <code>null</code>, since the refered object may be
|
|
* finalized and thus not accessible.
|
|
*/
|
|
public Object get()
|
|
{
|
|
return null;
|
|
}
|
|
}
|