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Java > Open Source Codes > org > jibx > binding > util > IntegerCache


1 /*
2 Copyright (c) 2003-2005, Dennis M. Sosnoski
3 All rights reserved.
4
5 Redistribution and use in source and binary forms, with or without modification,
6 are permitted provided that the following conditions are met:
7
8  * Redistributions of source code must retain the above copyright notice, this
9    list of conditions and the following disclaimer.
10  * Redistributions in binary form must reproduce the above copyright notice,
11    this list of conditions and the following disclaimer in the documentation
12    and/or other materials provided with the distribution.
13  * Neither the name of JiBX nor the names of its contributors may be used
14    to endorse or promote products derived from this software without specific
15    prior written permission.
16
17 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
18 ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
19 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
20 DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
21 ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
22 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
23 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
24 ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
26 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29 package org.jibx.binding.util;
30
31
32 /**
33  * Cache of <code>Integer</code> values. This is designed on the assumption that
34  * clients will start with zero and work their way up from there. By holding
35  * created instances in an array it allows for full reuse.
36  *
37  * @author Dennis M. Sosnoski
38  * @version 1.0
39  */
40
41 public abstract class IntegerCache
42 {
43     /** Initial set of index values supported. */
44     private static Integer JavaDoc[] s_integers =
45     {
46         new Integer JavaDoc(0), new Integer JavaDoc(1), new Integer JavaDoc(2), new Integer JavaDoc(3),
47         new Integer JavaDoc(4), new Integer JavaDoc(5), new Integer JavaDoc(6), new Integer JavaDoc(7)
48     };
49
50     /**
51      * Get <code>Integer</code> for value.
52      *
53      * @param value non-negative integer value
54      * @return corresponding <code>Integer</code> value
55      */
56
57     public static Integer JavaDoc getInteger(int value) {
58         if (value >= s_integers.length) {
59             
60             // Note that in multithreaded operation there's a chance of two
61 // threads getting in a race condition here, but the worst that
62 // can happen is that the array gets extended more than it needs
63 // to be. Threads just using the array are safe - though if they
64 // get an old version they may again extend the array
65 // unnecessarily.
66 synchronized(IntegerCache.class) {
67                 int size = s_integers.length * 3 / 2;
68                 if (size <= value) {
69                     size = value + 1;
70                 }
71                 Integer JavaDoc[] ints = new Integer JavaDoc[size];
72                 System.arraycopy(s_integers, 0, ints, 0, s_integers.length);
73                 for (int i = 0; i < size; i++) {
74                     ints[i] = new Integer JavaDoc(i);
75                 }
76                 s_integers = ints;
77             }
78         }
79         return s_integers[value];
80     }
81 }
82
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