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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    * 
9    *     http://www.apache.org/licenses/LICENSE-2.0
10   * 
11   * Unless required by applicable law or agreed to in writing, software 
12   * distributed under the License is distributed on an "AS IS" BASIS, 
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
14   * See the License for the specific language governing permissions and 
15   * limitations under the License.
16   */
17  
18  /*
19   * CharIdentity.java
20   *
21   */
22  
23  package javax.jdo.identity;
24  
25  import java.io.IOException;
26  import java.io.ObjectInput;
27  import java.io.ObjectOutput;
28  
29  import javax.jdo.spi.I18NHelper;
30  
31  /** This class is for identity with a single character field.
32   * @version 2.0
33   */
34  public class CharIdentity extends SingleFieldIdentity {
35  
36      /** The Internationalization message helper.
37       */
38      private static I18NHelper msg = I18NHelper.getInstance ("javax.jdo.Bundle"); //NOI18N
39  
40      /** The key.
41       */
42      private char key;
43  
44      private void construct(char key) {
45          this.key = key;
46          hashCode = hashClassName() ^ key;
47      }
48  
49      /** Constructor with class and key.
50       * @param pcClass the target class
51       * @param key the key
52       */
53      public CharIdentity (Class pcClass, char key) {
54          super (pcClass);
55          construct(key);
56      }
57  
58      /** Constructor with class and key.
59       * @param pcClass the target class
60       * @param key the key
61       */
62      public CharIdentity (Class pcClass, Character key) {
63          super (pcClass);
64          setKeyAsObject(key);
65          construct(key.charValue());
66      }
67  
68      /** Constructor with class and key. The String must have exactly one
69       * character.
70       * @param pcClass the target class
71       * @param str the key
72       */
73      public CharIdentity (Class pcClass, String str) {
74          super(pcClass);
75          assertKeyNotNull(str);
76          if (str.length() != 1) 
77              throw new IllegalArgumentException(
78                  msg.msg("EXC_StringWrongLength")); //NOI18N
79          construct(str.charAt(0));
80      }
81  
82      /** Constructor only for Externalizable.
83       */
84      public CharIdentity () {
85      }
86  
87      /** Return the key.
88       * @return the key
89       */
90      public char getKey () {
91          return key;
92      }
93  
94      /** Return the String form of the key.
95       * @return the String form of the key
96       */
97      public String toString () {
98          return String.valueOf(key);
99      }
100 
101     /** Determine if the other object represents the same object id.
102      * @param obj the other object
103      * @return true if both objects represent the same object id
104      */
105     public boolean equals (Object obj) {
106         if (this == obj) {
107             return true;
108         } else if (!super.equals (obj)) {
109             return false;
110         } else {
111             CharIdentity other = (CharIdentity) obj;
112             return key == other.key;
113         }
114     }
115 
116     /** Determine the ordering of identity objects.
117      * @param o Other identity
118      * @return The relative ordering between the objects
119      * @since 2.2
120      */
121     public int compareTo(Object o) {
122         if (o instanceof CharIdentity) {
123         	CharIdentity other = (CharIdentity)o;
124             int result = super.compare(other);
125             if (result == 0) {
126                 return (key - other.key);
127             } else {
128                 return result;
129             }
130         }
131         else if (o == null) {
132             throw new ClassCastException("object is null");
133         }
134         throw new ClassCastException(this.getClass().getName() + " != " + o.getClass().getName());
135     }
136 
137     /** Create the key as an Object.
138      * @return the key as an Object
139      * @since 2.0
140      */
141     protected Object createKeyAsObject() {
142         return new Character(key);
143     }
144 
145     /** Write this object. Write the superclass first.
146      * @param out the output
147      */
148     public void writeExternal(ObjectOutput out) throws IOException {
149         super.writeExternal (out);
150         out.writeChar(key);
151     }
152 
153     /** Read this object. Read the superclass first.
154      * @param in the input
155      */
156     public void readExternal(ObjectInput in)
157 		throws IOException, ClassNotFoundException {
158         super.readExternal (in);
159         key = in.readChar();
160     }
161 }