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Java > Open Source Codes > org > apache > tapestry > record > ChangeKey


1 // Copyright 2004, 2005 The Apache Software Foundation
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // http://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14
15 package org.apache.tapestry.record;
16
17 import org.apache.hivemind.util.Defense;
18
19 /**
20  * Used to identify a property change.
21  *
22  * @author Howard Lewis Ship
23  */
24
25 public class ChangeKey
26 {
27     private int _hashCode = -1;
28
29     private String JavaDoc _componentPath;
30
31     private String JavaDoc _propertyName;
32
33     public ChangeKey(String JavaDoc componentPath, String JavaDoc propertyName)
34     {
35         Defense.notNull(propertyName, "propertyName");
36
37         _componentPath = componentPath;
38         _propertyName = propertyName;
39     }
40
41     public boolean equals(Object JavaDoc object)
42     {
43         if (object == null)
44             return false;
45
46         if (this == object)
47             return true;
48
49         if (!(object instanceof ChangeKey))
50             return false;
51
52         ChangeKey other = (ChangeKey) object;
53
54         return same(_propertyName, other._propertyName)
55                 && same(_componentPath, other._componentPath);
56     }
57
58     private boolean same(String JavaDoc s1, String JavaDoc s2)
59     {
60         return s1 == s2 || (s1 != null && s1.equals(s2));
61     }
62
63     public String JavaDoc getComponentPath()
64     {
65         return _componentPath;
66     }
67
68     public String JavaDoc getPropertyName()
69     {
70         return _propertyName;
71     }
72
73     /**
74      * Returns a hash code computed from the property name and component path.
75      */
76
77     public int hashCode()
78     {
79         if (_hashCode == -1)
80         {
81             _hashCode = 31 * 27 + _propertyName.hashCode();
82
83             if (_componentPath != null)
84                 _hashCode = 31 * _hashCode + _componentPath.hashCode();
85         }
86
87         return _hashCode;
88     }
89 }
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