1 package org.apache.torque.om;
2
3 /* ====================================================================
4 * The Apache Software License, Version 1.1
5 *
6 * Copyright (c) 2001 The Apache Software Foundation. All rights
7 * reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 *
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 *
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in
18 * the documentation and/or other materials provided with the
19 * distribution.
20 *
21 * 3. The end-user documentation included with the redistribution,
22 * if any, must include the following acknowledgment:
23 * "This product includes software developed by the
24 * Apache Software Foundation (http://www.apache.org/)."
25 * Alternately, this acknowledgment may appear in the software itself,
26 * if and wherever such third-party acknowledgments normally appear.
27 *
28 * 4. The names "Apache" and "Apache Software Foundation" and
29 * "Apache Turbine" must not be used to endorse or promote products
30 * derived from this software without prior written permission. For
31 * written permission, please contact apache@apache.org.
32 *
33 * 5. Products derived from this software may not be called "Apache",
34 * "Apache Turbine", nor may "Apache" appear in their name, without
35 * prior written permission of the Apache Software Foundation.
36 *
37 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
38 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
39 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
40 * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
41 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
42 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
43 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
44 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
45 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
46 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
47 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
48 * SUCH DAMAGE.
49 * ====================================================================
50 *
51 * This software consists of voluntary contributions made by many
52 * individuals on behalf of the Apache Software Foundation. For more
53 * information on the Apache Software Foundation, please see
54 * <http://www.apache.org/>.
55 */
56
57 import java.io.Serializable;
58 import org.apache.torque.TorqueException;
59
60 /***
61 * This class can be used to uniquely identify an object within
62 * an application. There are four subclasses: StringKey, NumberKey,
63 * and DateKey, and ComboKey which is a Key made up of a combination
64 * ofthe first three.
65 *
66 * @author <a href="mailto:jmcnally@apache.org">John McNally</a>
67 * @version $Id: ObjectKey.java,v 1.6 2002/11/26 22:32:55 mpoeschl Exp $
68 */
69 public abstract class ObjectKey implements Serializable, Comparable
70 {
71 /***
72 * The underlying key value.
73 */
74 protected Object key;
75
76 /***
77 * Initializes the internal key value to <code>null</code>.
78 */
79 protected ObjectKey()
80 {
81 key = null;
82 }
83
84 /***
85 * Returns the hashcode of the underlying value (key), if key is
86 * not null. Otherwise calls Object.hashCode()
87 *
88 * @return an <code>int</code> value
89 */
90 public int hashCode()
91 {
92 if (key == null)
93 {
94 return super.hashCode();
95 }
96 return key.hashCode();
97 }
98
99 /***
100 * Get the underlying object.
101 *
102 * @return the underlying object
103 */
104 public Object getValue()
105 {
106 return key;
107 }
108
109 /***
110 * Appends a String representation of the key to a buffer.
111 *
112 * @param sb a <code>StringBuffer</code>
113 */
114 public void appendTo(StringBuffer sb)
115 {
116 sb.append(this.toString());
117 }
118
119 /***
120 * Implements the compareTo method.
121 *
122 * @param obj the object to compare to this object
123 * @return a numeric comparison of the two values
124 */
125 public int compareTo(Object obj)
126 {
127 return toString().compareTo(obj.toString());
128 }
129
130 /***
131 * Reset the underlying object using a String.
132 *
133 * @param s a <code>String</code> value
134 * @exception TorqueException if an error occurs
135 */
136 public abstract void setValue(String s) throws TorqueException;
137 }