1 /*
   2  * Copyright (c) 2011, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 package gc.gctests.PhantomReference;
  24 
  25 import java.lang.ref.PhantomReference;
  26 import java.lang.ref.ReferenceQueue;
  27 
  28 /**
  29  * Helper class that extends PhantomReference, that we can use
  30  * to match the hash code for the referent object.
  31  */
  32 public final class PRHelper extends PhantomReference {
  33 
  34     private int referentHashCode;
  35 
  36     /**
  37      * Constructor for extended PhantomReference class.
  38      *
  39      * @param o              Referred object
  40      * @param referenceQueue Reference queue to attach the PR to
  41      */
  42     public PRHelper(Object o, ReferenceQueue referenceQueue) {
  43         super(o, referenceQueue);
  44         referentHashCode = -1;
  45     }
  46 
  47     /**
  48      * Get the referred objects hash code.
  49      *
  50      * @return Hash code for referred object
  51      */
  52     public int getReferentHashCode() {
  53         return referentHashCode;
  54     }
  55 
  56     /**
  57      * Set the original referred objects hash code for tracking.
  58      *
  59      * @param referentHashCode New hash code
  60      */
  61     public void setReferentHashCode(int referentHashCode) {
  62         this.referentHashCode = referentHashCode;
  63     }
  64 }