diff -r 000000000000 -r 5198affdb915 emul/compact/src/main/java/java/lang/ref/PhantomReference.java --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/emul/compact/src/main/java/java/lang/ref/PhantomReference.java Mon Jan 28 18:12:47 2013 +0100 @@ -0,0 +1,83 @@ +/* + * 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 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 super T> q) {
+ super(referent, q);
+ }
+
+}
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.
+ *
+ *