diff -r 3392f250c784 -r ecbd252fd3a7 emul/compact/src/main/java/java/lang/ref/PhantomReference.java --- a/emul/compact/src/main/java/java/lang/ref/PhantomReference.java Fri Mar 22 16:59:47 2013 +0100 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000 @@ -1,83 +0,0 @@ -/* - * Copyright (c) 1997, 2003, Oracle and/or its affiliates. All rights reserved. - * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. - * - * This code is free software; you can redistribute it and/or modify it - * under the terms of the GNU General Public License version 2 only, as - * published by the Free Software Foundation. Oracle designates this - * particular file as subject to the "Classpath" exception as provided - * by Oracle in the LICENSE file that accompanied this code. - * - * This code 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 - * version 2 for more details (a copy is included in the LICENSE file that - * accompanied this code). - * - * You should have received a copy of the GNU General Public License version - * 2 along with this work; if not, write to the Free Software Foundation, - * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. - * - * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA - * or visit www.oracle.com if you need additional information or have any - * questions. - */ - -package java.lang.ref; - - -/** - * Phantom reference objects, which are enqueued after the collector - * determines that their referents may otherwise be reclaimed. Phantom - * references are most often used for scheduling pre-mortem cleanup actions in - * a more flexible way than is possible with the Java finalization mechanism. - * - *

If the garbage collector determines at a certain point in time that the - * referent of a phantom reference is phantom reachable, then at that - * time or at some later time it will enqueue the reference. - * - *

In order to ensure that a reclaimable object remains so, the referent of - * a phantom reference may not be retrieved: The get method of a - * phantom reference always returns null. - * - *

Unlike soft and weak references, phantom references are not - * automatically cleared by the garbage collector as they are enqueued. An - * object that is reachable via phantom references will remain so until all - * such references are cleared or themselves become unreachable. - * - * @author Mark Reinhold - * @since 1.2 - */ - -public class PhantomReference extends Reference { - - /** - * Returns this reference object's referent. Because the referent of a - * phantom reference is always inaccessible, this method always returns - * null. - * - * @return null - */ - public T get() { - return null; - } - - /** - * Creates a new phantom reference that refers to the given object and - * is registered with the given queue. - * - *

It is possible to create a phantom reference with a null - * queue, but such a reference is completely useless: Its get - * method will always return null and, since it does not have a queue, it - * will never be enqueued. - * - * @param referent the object the new phantom reference will refer to - * @param q the queue with which the reference is to be registered, - * or null if registration is not required - */ - public PhantomReference(T referent, ReferenceQueue q) { - super(referent, q); - } - -}