1 /*
2 * Copyright (c) 2003, Henri Yandell
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or
6 * without modification, are permitted provided that the
7 * following conditions are met:
8 *
9 * + Redistributions of source code must retain the above copyright notice,
10 * this list of conditions and the following disclaimer.
11 *
12 * + Redistributions in binary form must reproduce the above copyright notice,
13 * this list of conditions and the following disclaimer in the documentation
14 * and/or other materials provided with the distribution.
15 *
16 * + Neither the name of Genjava-Core nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
21 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
24 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
30 * POSSIBILITY OF SUCH DAMAGE.
31 */
32 package com.generationjava.collections;
33
34 import java.util.Comparator;
35 import java.util.Hashtable;
36
37 /***
38 * If the Objects to be compared are known before hand, then this allows
39 * the ordering to be handled via the construction of an Object[].
40 */
41 public class GroupedComparator implements Comparator {
42
43 private Hashtable index = new Hashtable();
44
45 /***
46 * Provide an array of Objects that will be compared.
47 * The order the Objects are in the array is the order in which
48 * they will be sorted.
49 */
50 public GroupedComparator(Object[] objs) {
51 int sz = objs.length;
52
53 for(int i=0; i<sz; i++) {
54 index.put(objs[i], new Integer(i));
55 }
56 }
57
58 public int compare(Object o1, Object o2) {
59 Integer i1 = (Integer)index.get(o1);
60 Integer i2 = (Integer)index.get(o2);
61 if(i2 == null) {
62 return -1;
63 } else
64 if(i1 == null) {
65 return 1;
66 }
67
68 if( i1.intValue() < i2.intValue() ) {
69 return -1;
70 } else
71 if( i1.intValue() > i2.intValue() ) {
72 return 1;
73 } else {
74 return 0;
75 }
76 }
77
78 }
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