01: /*
02: *
03: *
04: * Copyright 1990-2007 Sun Microsystems, Inc. All Rights Reserved.
05: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
06: *
07: * This program is free software; you can redistribute it and/or
08: * modify it under the terms of the GNU General Public License version
09: * 2 only, as published by the Free Software Foundation.
10: *
11: * This program is distributed in the hope that it will be useful, but
12: * WITHOUT ANY WARRANTY; without even the implied warranty of
13: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14: * General Public License version 2 for more details (a copy is
15: * included at /legal/license.txt).
16: *
17: * You should have received a copy of the GNU General Public License
18: * version 2 along with this work; if not, write to the Free Software
19: * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
20: * 02110-1301 USA
21: *
22: * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
23: * Clara, CA 95054 or visit www.sun.com if you need additional
24: * information or have any questions.
25: */
26:
27: package java.lang.ref;
28:
29: /**
30: * Abstract base class for reference objects. This class defines the
31: * operations common to all reference objects. Because reference objects are
32: * implemented in close cooperation with the garbage collector, this class may
33: * not be subclassed directly.
34: *
35: * @version 12/19/01 (CLDC 1.1)
36: * @since JDK1.2, CLDC 1.1
37: */
38:
39: public abstract class Reference {
40:
41: /* -- Referent accessor and setters -- */
42:
43: /**
44: * Returns this reference object's referent. If this reference object has
45: * been cleared, either by the program or by the garbage collector, then
46: * this method returns <code>null</code>.
47: *
48: * @return The object to which this reference refers, or
49: * <code>null</code> if this reference object has been cleared
50: */
51: public Object get() {
52: return null;
53: }
54:
55: /**
56: * Clears this reference object.
57: */
58: public void clear() {
59: }
60:
61: /* -- Constructors -- */
62:
63: Reference(Object referent) {
64: }
65: }
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