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1 /* |
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2 * Copyright (c) 1997, 2003, Oracle and/or its affiliates. All rights reserved. |
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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4 * |
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5 * This code is free software; you can redistribute it and/or modify it |
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6 * under the terms of the GNU General Public License version 2 only, as |
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7 * published by the Free Software Foundation. Oracle designates this |
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8 * particular file as subject to the "Classpath" exception as provided |
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9 * by Oracle in the LICENSE file that accompanied this code. |
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10 * |
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11 * This code is distributed in the hope that it will be useful, but WITHOUT |
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12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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14 * version 2 for more details (a copy is included in the LICENSE file that |
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15 * accompanied this code). |
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16 * |
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17 * You should have received a copy of the GNU General Public License version |
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18 * 2 along with this work; if not, write to the Free Software Foundation, |
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19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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20 * |
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21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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22 * or visit www.oracle.com if you need additional information or have any |
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23 * questions. |
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24 */ |
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25 |
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26 package java.lang.ref; |
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27 |
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28 |
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29 /** |
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30 * Weak reference objects, which do not prevent their referents from being |
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31 * made finalizable, finalized, and then reclaimed. Weak references are most |
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32 * often used to implement canonicalizing mappings. |
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33 * |
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34 * <p> Suppose that the garbage collector determines at a certain point in time |
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35 * that an object is <a href="package-summary.html#reachability">weakly |
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36 * reachable</a>. At that time it will atomically clear all weak references to |
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37 * that object and all weak references to any other weakly-reachable objects |
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38 * from which that object is reachable through a chain of strong and soft |
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39 * references. At the same time it will declare all of the formerly |
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40 * weakly-reachable objects to be finalizable. At the same time or at some |
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41 * later time it will enqueue those newly-cleared weak references that are |
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42 * registered with reference queues. |
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43 * |
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44 * @author Mark Reinhold |
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45 * @since 1.2 |
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46 */ |
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47 |
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48 public class WeakReference<T> extends Reference<T> { |
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49 |
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50 /** |
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51 * Creates a new weak reference that refers to the given object. The new |
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52 * reference is not registered with any queue. |
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53 * |
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54 * @param referent object the new weak reference will refer to |
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55 */ |
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56 public WeakReference(T referent) { |
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57 super(referent); |
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58 } |
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59 |
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60 /** |
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61 * Creates a new weak reference that refers to the given object and is |
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62 * registered with the given queue. |
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63 * |
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64 * @param referent object the new weak reference will refer to |
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65 * @param q the queue with which the reference is to be registered, |
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66 * or <tt>null</tt> if registration is not required |
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67 */ |
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68 public WeakReference(T referent, ReferenceQueue<? super T> q) { |
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69 super(referent, q); |
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70 } |
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71 |
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72 } |