1 /***
2 * Redistribution and use of this software and associated documentation
3 * ("Software"), with or without modification, are permitted provided
4 * that the following conditions are met:
5 *
6 * 1. Redistributions of source code must retain copyright
7 * statements and notices. Redistributions must also contain a
8 * copy of this document.
9 *
10 * 2. Redistributions in binary form must reproduce the
11 * above copyright notice, this list of conditions and the
12 * following disclaimer in the documentation and/or other
13 * materials provided with the distribution.
14 *
15 * 3. The name "Exolab" must not be used to endorse or promote
16 * products derived from this Software without prior written
17 * permission of Exoffice Technologies. For written permission,
18 * please contact info@exolab.org.
19 *
20 * 4. Products derived from this Software may not be called "Exolab"
21 * nor may "Exolab" appear in their names without prior written
22 * permission of Exoffice Technologies. Exolab is a registered
23 * trademark of Exoffice Technologies.
24 *
25 * 5. Due credit should be given to the Exolab Project
26 * (http://www.exolab.org/).
27 *
28 * THIS SOFTWARE IS PROVIDED BY EXOFFICE TECHNOLOGIES AND CONTRIBUTORS
29 * ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
30 * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
31 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
32 * EXOFFICE TECHNOLOGIES OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
33 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
34 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
35 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
36 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
37 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
38 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
39 * OF THE POSSIBILITY OF SUCH DAMAGE.
40 *
41 * Copyright 2000 (C) Exoffice Technologies Inc. All Rights Reserved.
42 *
43 * $Id: IdKeyComparator.java,v 1.4 2003/08/17 01:32:25 tanderson Exp $
44 *
45 * Date Author Changes
46 * $Date jimm Created
47 */
48
49
50 package org.exolab.jms.persistence;
51
52 import java.io.Serializable;
53 import java.util.Comparator;
54
55 import javax.jms.JMSException;
56
57
58 /***
59 * A comparator class that iplements a string comparison.
60 *
61 *
62 * <P>Note this class assumes that id's are in some sort of order, such that
63 * an earlier generated id is less than a later generated id.
64 *
65 * @version $Revision: 1.4 $ $Date: 2003/08/17 01:32:25 $
66 * @author <a href="mailto:mourikis@exolab.org">Jim Mourikis</a>
67 */
68 public class IdKeyComparator implements Comparator, Serializable {
69
70
71 private static final int PREFIX_LENGTH = 3;
72
73 /***
74 * Default constructor does nothing.
75 *
76 */
77 public IdKeyComparator() {
78
79 }
80
81
82 /***
83 * Implements the compare operator.
84 * Compares its two arguments for order. Returns a negative integer, zero,
85 * or a positive integer as the first argument is less than, equal to,
86 * or greater than the second.
87 *
88 * @param Object object 1 to compare
89 * @param Object object 2 ro compare to.
90 * @return int returns -1, 0, 1 if the first argument is less than,
91 * equal to, or greater than the second.
92 * @exception ClassCastException if object types are unknown
93 *
94 */
95 public int compare(Object o1, Object o2)
96 throws ClassCastException, NullPointerException {
97 int status = 0;
98
99 if (o1 == null && o2 == null)
100 status = 0;
101 else if (o1 == null)
102 status = -1;
103 else if (o2 == null)
104 status = 1;
105 else if (o1 instanceof String &&
106 o2 instanceof String) {
107 String t1 = (String) o1;
108 String t2 = (String) o2;
109 try {
110 long l1 = strip(t1);
111 long l2 = strip(t2);
112
113 if (l1 == l2)
114 status = 0;
115 else if (l1 < l2)
116 status = -1;
117 else
118 status = 1;
119 } catch (NumberFormatException err) {
120 System.err.println("Invalid IDs " + t1 + ", " + t2);
121 }
122 } else {
123 throw new ClassCastException("Unknown Object");
124 }
125 return status;
126 }
127
128
129 /***
130 * Indicates whether some other object is "equal to" this Comparator.
131 * This method must obey the general contract of Object.equals(Object).
132 *
133 * @param Object the object to compare to
134 * @return boolean true iff objects are equal
135 *
136 */
137 public boolean equals(Object ob) {
138 boolean status = false;
139
140 if (ob instanceof IdKeyComparator) status = true;
141
142 return status;
143 }
144
145
146 /***
147 * Strip the "ID:" prefix from the string, and return the long number
148 * remaininng.
149 *
150 * @param st The string to strip.
151 * @return long the remaing long integer.
152 *
153 */
154 private long strip(String st) throws NumberFormatException {
155 return Long.parseLong(st.substring(PREFIX_LENGTH));
156 }
157 }
158
159
160