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1   /**
2    * JDBM LICENSE v1.00
3    *
4    * Redistribution and use of this software and associated documentation
5    * ("Software"), with or without modification, are permitted provided
6    * that the following conditions are met:
7    *
8    * 1. Redistributions of source code must retain copyright
9    *    statements and notices.  Redistributions must also contain a
10   *    copy of this document.
11   *
12   * 2. Redistributions in binary form must reproduce the
13   *    above copyright notice, this list of conditions and the
14   *    following disclaimer in the documentation and/or other
15   *    materials provided with the distribution.
16   *
17   * 3. The name "JDBM" must not be used to endorse or promote
18   *    products derived from this Software without prior written
19   *    permission of Cees de Groot.  For written permission,
20   *    please contact cg@cdegroot.com.
21   *
22   * 4. Products derived from this Software may not be called "JDBM"
23   *    nor may "JDBM" appear in their names without prior written
24   *    permission of Cees de Groot.
25   *
26   * 5. Due credit should be given to the JDBM Project
27   *    (http://jdbm.sourceforge.net/).
28   *
29   * THIS SOFTWARE IS PROVIDED BY THE JDBM PROJECT AND CONTRIBUTORS
30   * ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
31   * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
32   * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
33   * CEES DE GROOT OR ANY CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
34   * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
35   * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
36   * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
37   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
38   * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
39   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
40   * OF THE POSSIBILITY OF SUCH DAMAGE.
41   *
42   * Copyright 2001 (C) Alex Boisvert. All Rights Reserved.
43   * Contributions are Copyright (C) 2001 by their associated contributors.
44   *
45   */
46  
47  package jdbm.helper;
48  
49  import java.util.Comparator;
50  import java.io.Serializable;
51  
52  /**
53   * Comparator for byte arrays.
54   *
55   * @author <a href="mailto:boisvert@intalio.com">Alex Boisvert</a>
56   * @version $Id: ByteArrayComparator.java,v 1.4 2002/05/31 06:33:20 boisvert Exp $
57   */
58  public final class ByteArrayComparator
59      implements Comparator, Serializable
60  {
61  
62      /**
63       * Version id for serialization.
64       */
65      final static long serialVersionUID = 1L;
66  
67  
68      /**
69       * Compare two objects.
70       *
71       * @param obj1 First object
72       * @param obj2 Second object
73       * @return a positive integer if obj1 > obj2, 0 if obj1 == obj2,
74       *         and a negative integer if obj1 < obj2
75       */
76       public int compare( Object obj1, Object obj2 )
77       {
78          if ( obj1 == null ) {
79              throw new IllegalArgumentException( "Argument 'obj1' is null" );
80          }
81  
82          if ( obj2 == null ) {
83              throw new IllegalArgumentException( "Argument 'obj2' is null" );
84          }
85  
86          return compareByteArray( (byte[]) obj1, (byte[]) obj2 );
87       }
88  
89  
90      /**
91       * Compare two byte arrays.
92       */
93      public static int compareByteArray( byte[] thisKey, byte[] otherKey )
94      {
95          int len = Math.min( thisKey.length, otherKey.length );
96  
97          // compare the byte arrays
98          for ( int i=0; i<len; i++ ) {
99              if ( thisKey[i] >= 0 ) {
100                 if ( otherKey[i] >= 0 ) {
101                     // both positive
102                     if ( thisKey[i] < otherKey[i] ) {
103                         return -1;
104                     } else if ( thisKey[i] > otherKey[i] ) {
105                         return 1;
106                     }
107                 } else {
108                     // otherKey is negative => greater (because MSB is 1)
109                     return -1;
110                 }
111             } else {
112                 if ( otherKey[i] >= 0 ) {
113                     // thisKey is negative => greater (because MSB is 1)
114                     return 1;
115                 } else {
116                     // both negative
117                     if ( thisKey[i] < otherKey[i] ) {
118                         return -1;
119                     } else if ( thisKey[i] > otherKey[i] ) {
120                         return 1;
121                     }
122                 }
123             }
124         }
125         if ( thisKey.length == otherKey.length) {
126             return 0;
127         }
128         if ( thisKey.length < otherKey.length ) {
129             return -1;
130         }
131         return 1;
132     }
133 
134 }