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Java > Open Source Codes > javax > jdo > identity > StringIdentity


1 /*
2  * Copyright 2005 The Apache Software Foundation.
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16
17 /*
18  * StringIdentity.java
19  *
20  */
21  
22 package javax.jdo.identity;
23
24 import java.io.IOException JavaDoc;
25 import java.io.ObjectInput JavaDoc;
26 import java.io.ObjectOutput JavaDoc;
27
28 import javax.jdo.JDOUserException;
29
30 /** This class is for identity with a single String field.
31  * @version 2.0
32  */
33 public class StringIdentity extends SingleFieldIdentity {
34     
35     /** The key is stored in the superclass field keyAsObject.
36      */
37     
38     /** Constructor with class and key.
39      * @param pcClass the class
40      * @param key the key
41      */
42     public StringIdentity (Class JavaDoc pcClass, String JavaDoc key) {
43         super (pcClass);
44         setKeyAsObject(key);
45         hashCode = hashClassName() ^ key.hashCode();
46     }
47
48     /** Constructor only for Externalizable.
49      */
50     public StringIdentity () {
51     }
52
53     /** Return the key.
54      * @return the key
55      */
56     public String JavaDoc getKey () {
57         return (String JavaDoc)keyAsObject;
58     }
59
60     /** Return the String form of the key.
61      * @return the String form of the key
62      */
63     public String JavaDoc toString () {
64         return (String JavaDoc)keyAsObject;
65     }
66
67     /** Determine if the other object represents the same object id.
68      * @param obj the other object
69      * @return true if both objects represent the same object id
70      */
71     public boolean equals (Object JavaDoc obj) {
72         if (this == obj) {
73             return true;
74         } else if (!super.equals (obj)) {
75             return false;
76         } else {
77             StringIdentity other = (StringIdentity) obj;
78             return keyAsObject.equals(other.keyAsObject);
79         }
80     }
81
82     /** Write this object. Write the superclass first.
83      * @param out the output
84      */
85     public void writeExternal(ObjectOutput JavaDoc out) throws IOException JavaDoc {
86         super.writeExternal (out);
87         out.writeObject(keyAsObject);
88     }
89
90     /** Read this object. Read the superclass first.
91      * @param in the input
92      */
93     public void readExternal(ObjectInput JavaDoc in)
94         throws IOException JavaDoc, ClassNotFoundException JavaDoc {
95         super.readExternal (in);
96         keyAsObject = (String JavaDoc)in.readObject();
97     }
98 }
99
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