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1   package org.apache.commons.jcs.engine.control.group;
2   
3   /*
4    * Licensed to the Apache Software Foundation (ASF) under one
5    * or more contributor license agreements.  See the NOTICE file
6    * distributed with this work for additional information
7    * regarding copyright ownership.  The ASF licenses this file
8    * to you under the Apache License, Version 2.0 (the
9    * "License"); you may not use this file except in compliance
10   * with the License.  You may obtain a copy of the License at
11   *
12   *   http://www.apache.org/licenses/LICENSE-2.0
13   *
14   * Unless required by applicable law or agreed to in writing,
15   * software distributed under the License is distributed on an
16   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17   * KIND, either express or implied.  See the License for the
18   * specific language governing permissions and limitations
19   * under the License.
20   */
21  
22  import java.io.Serializable;
23  
24  /**
25   * Description of the Class
26   */
27  public class GroupAttrName<T>
28      implements Serializable
29  {
30      /** Don't change */
31      private static final long serialVersionUID = 1586079686300744198L;
32  
33      /** Description of the Field */
34      public final GroupId groupId;
35  
36      /** the name of the attribute */
37      public final T attrName;
38  
39      /** Cached toString value */
40      private String toString;
41  
42      /**
43       * Constructor for the GroupAttrName object
44       * @param groupId
45       * @param attrName
46       */
47      public GroupAttrName( GroupId groupId, T attrName )
48      {
49          this.groupId = groupId;
50          this.attrName = attrName;
51  
52          if ( groupId == null )
53          {
54              throw new IllegalArgumentException( "groupId must not be null." );
55          }
56      }
57  
58      /**
59       * Tests object equality.
60       * @param obj The <code>GroupAttrName</code> instance to test.
61       * @return Whether equal.
62       */
63      @Override
64      public boolean equals( Object obj )
65      {
66          if ( obj == null || !( obj instanceof GroupAttrName ) )
67          {
68              return false;
69          }
70          GroupAttrName<?> to = (GroupAttrName<?>) obj;
71  
72          if (groupId.equals( to.groupId ))
73          {
74              if (attrName == null && to.attrName == null)
75              {
76                  return true;
77              }
78              else if (attrName == null || to.attrName == null)
79              {
80                  return false;
81              }
82  
83              return  attrName.equals( to.attrName );
84          }
85  
86          return false;
87      }
88  
89      /**
90       * @return A hash code based on the hash code of @ #groupid} and {@link #attrName}.
91       */
92      @Override
93      public int hashCode()
94      {
95          if (attrName == null)
96          {
97              return groupId.hashCode();
98          }
99  
100         return groupId.hashCode() ^ attrName.hashCode();
101     }
102 
103     /**
104      * @return the cached value.
105      */
106     @Override
107     public String toString()
108     {
109         if ( toString == null )
110         {
111             toString = "[GAN: groupId=" + groupId + ", attrName=" + attrName + "]";
112         }
113 
114         return toString;
115     }
116 
117 }