2362N/A * Copyright (c) 1997, 2003, Oracle and/or its affiliates. All rights reserved. 0N/A * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 0N/A * This code is free software; you can redistribute it and/or modify it 0N/A * under the terms of the GNU General Public License version 2 only, as 2362N/A * published by the Free Software Foundation. Oracle designates this 0N/A * particular file as subject to the "Classpath" exception as provided 2362N/A * by Oracle in the LICENSE file that accompanied this code. 0N/A * This code is distributed in the hope that it will be useful, but WITHOUT 0N/A * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 0N/A * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 0N/A * version 2 for more details (a copy is included in the LICENSE file that 0N/A * accompanied this code). 0N/A * You should have received a copy of the GNU General Public License version 0N/A * 2 along with this work; if not, write to the Free Software Foundation, 0N/A * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 2362N/A * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 2362N/A * or visit www.oracle.com if you need additional information or have any 0N/A * Phantom reference objects, which are enqueued after the collector 0N/A * determines that their referents may otherwise be reclaimed. Phantom 0N/A * references are most often used for scheduling pre-mortem cleanup actions in 0N/A * a more flexible way than is possible with the Java finalization mechanism. 0N/A * <p> If the garbage collector determines at a certain point in time that the 0N/A * referent of a phantom reference is <a 0N/A * time or at some later time it will enqueue the reference. 0N/A * <p> In order to ensure that a reclaimable object remains so, the referent of 0N/A * a phantom reference may not be retrieved: The <code>get</code> method of a 0N/A * phantom reference always returns <code>null</code>. 0N/A * <p> Unlike soft and weak references, phantom references are not 0N/A * automatically cleared by the garbage collector as they are enqueued. An 0N/A * object that is reachable via phantom references will remain so until all 0N/A * such references are cleared or themselves become unreachable. 0N/A * @author Mark Reinhold 0N/A * Returns this reference object's referent. Because the referent of a 0N/A * phantom reference is always inaccessible, this method always returns 0N/A * <code>null</code>. 0N/A * @return <code>null</code> 0N/A * Creates a new phantom reference that refers to the given object and 0N/A * is registered with the given queue. 0N/A * <p> It is possible to create a phantom reference with a <tt>null</tt> 0N/A * queue, but such a reference is completely useless: Its <tt>get</tt> 0N/A * method will always return null and, since it does not have a queue, it 0N/A * will never be enqueued. 0N/A * @param referent the object the new phantom reference will refer to 0N/A * @param q the queue with which the reference is to be registered, 0N/A * or <tt>null</tt> if registration is not required