01: /*
02: * (C) Copyright 2004 Nabh Information Systems, Inc.
03: *
04: * All copyright notices regarding Nabh's products MUST remain
05: * intact in the scripts and in the outputted HTML.
06: * This program is free software; you can redistribute it and/or
07: * modify it under the terms of the GNU Lesser General Public License
08: * as published by the Free Software Foundation; either version 2.1
09: * of the License, or (at your option) any later version.
10: *
11: * This program is distributed in the hope that it will be useful,
12: * but WITHOUT ANY WARRANTY; without even the implied warranty of
13: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14: * GNU Lesser General Public License for more details.
15: *
16: * You should have received a copy of the GNU Lesser General Public License
17: * along with this program; if not, write to the Free Software
18: * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
19: *
20: */
21:
22: package com.nabhinc.core;
23:
24: /**
25: * Placeholder for passing null objects.
26: *
27: * @author Padmanabh Dabke
28: * (c) 2004 Nabh Information Systems, Inc. All Rights Reserved.
29: */
30: public class NullObject implements java.io.Serializable {
31: /**
32: * Comment for <code>serialVersionUID</code>
33: */
34: private static final long serialVersionUID = 3257853177314751800L;
35: private static NullObject singleton = new NullObject();
36:
37: /**
38: * Private do nothing constructor.
39: */
40: private NullObject() {
41: }
42:
43: /**
44: * Get the singleton instance of the class.
45: */
46: public static NullObject getInstance() {
47: return singleton;
48: }
49:
50: /**
51: * Returns string "null".
52: */
53: public String toString() {
54: return "null";
55: }
56: }
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