01: //
02: // Copyright (C) 2005 United States Government as represented by the
03: // Administrator of the National Aeronautics and Space Administration
04: // (NASA). All Rights Reserved.
05: //
06: // This software is distributed under the NASA Open Source Agreement
07: // (NOSA), version 1.3. The NOSA has been approved by the Open Source
08: // Initiative. See the file NOSA-1.3-JPF at the top of the distribution
09: // directory tree for the complete NOSA document.
10: //
11: // THE SUBJECT SOFTWARE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY OF ANY
12: // KIND, EITHER EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT
13: // LIMITED TO, ANY WARRANTY THAT THE SUBJECT SOFTWARE WILL CONFORM TO
14: // SPECIFICATIONS, ANY IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR
15: // A PARTICULAR PURPOSE, OR FREEDOM FROM INFRINGEMENT, ANY WARRANTY THAT
16: // THE SUBJECT SOFTWARE WILL BE ERROR FREE, OR ANY WARRANTY THAT
17: // DOCUMENTATION, IF PROVIDED, WILL CONFORM TO THE SUBJECT SOFTWARE.
18: //
19: package java.lang.ref;
20:
21: /**
22: * MJI model class for java.lang.ref.Reference library abstraction
23: * we model this so that we can rely on our WeakRefence implementation
24: */
25: public abstract class Reference {
26:
27: /**
28: * the object we reference
29: * NOTE: this has to be the *first* field, or we break WeakReference handling in
30: * the garbage collection!!
31: */
32: Object ref;
33:
34: /** the optional queue for us */
35: ReferenceQueue queue;
36:
37: /** link to enqueue w/o additional memory requirements */
38: Reference next;
39:
40: Reference(Object r) {
41: ref = r;
42: }
43:
44: Reference(Object r, ReferenceQueue q) {
45: ref = r;
46: queue = q;
47: }
48:
49: /** is the referenced object enqueued */
50: public boolean isEnqueued() {
51: // <2do>
52: return false;
53: }
54:
55: /** clear, but do not enqueue the referenced object */
56: public void clear() {
57: ref = null;
58: }
59:
60: /** add the referenced object to its queue */
61: public void enqueue() {
62: }
63:
64: /** return the referenced object */
65: public Object get() {
66: return ref;
67: }
68: }
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