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Java > Open Source Codes > org > jfree > chart > HashUtilities


1 /* ===========================================================
2  * JFreeChart : a free chart library for the Java(tm) platform
3  * ===========================================================
4  *
5  * (C) Copyright 2000-2006, by Object Refinery Limited and Contributors.
6  *
7  * Project Info: http://www.jfree.org/jfreechart/index.html
8  *
9  * This library is free software; you can redistribute it and/or modify it
10  * under the terms of the GNU Lesser General Public License as published by
11  * the Free Software Foundation; either version 2.1 of the License, or
12  * (at your option) any later version.
13  *
14  * This library is distributed in the hope that it will be useful, but
15  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
16  * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
17  * License for more details.
18  *
19  * You should have received a copy of the GNU Lesser General Public
20  * License along with this library; if not, write to the Free Software
21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
22  * USA.
23  *
24  * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
25  * in the United States and other countries.]
26  *
27  * ------------------
28  * HashUtilities.java
29  * ------------------
30  * (C) Copyright 2006, by Object Refinery Limited;
31  *
32  * Original Author: David Gilbert (for Object Refinery Limited);
33  * Contributor(s): -;
34  *
35  * $Id: HashUtilities.java,v 1.1.2.1 2006/11/03 17:00:51 mungady Exp $
36  *
37  * Changes
38  * -------
39  * 03-Oct-2006 : Version 1 (DG);
40
41  *
42  */
43
44 package org.jfree.chart;
45
46 import java.awt.GradientPaint JavaDoc;
47 import java.awt.Paint JavaDoc;
48
49 /**
50  * Some utility methods for calculating hash codes.
51  *
52  * @since 1.0.3
53  */
54 public class HashUtilities {
55     
56     /**
57      * Returns a hash code for a <code>Paint</code> instance. If
58      * <code>p</code> is <code>null</code>, this method returns zero.
59      *
60      * @param p the paint (<code>null</code> permitted).
61      *
62      * @return The hash code.
63      */
64     public static int hashCodeForPaint(Paint JavaDoc p) {
65         if (p == null)
66             return 0;
67         int result = 0;
68         // handle GradientPaint as a special case
69 if (p instanceof GradientPaint JavaDoc) {
70             GradientPaint JavaDoc gp = (GradientPaint JavaDoc) p;
71             result = 193;
72             result = 37 * result + gp.getColor1().hashCode();
73             result = 37 * result + gp.getPoint1().hashCode();
74             result = 37 * result + gp.getColor2().hashCode();
75             result = 37 * result + gp.getPoint2().hashCode();
76         }
77         else {
78             // we assume that all other Paint instances implement equals() and
79 // hashCode()...of course that might not be true, but what can we
80 // do about it?
81 result = p.hashCode();
82         }
83         return result;
84     }
85     
86     /**
87      * Returns a hash code for a <code>double[]</code> instance. If the array
88      * is <code>null</code>, this method returns zero.
89      *
90      * @param a the array (<code>null</code> permitted).
91      *
92      * @return The hash code.
93      */
94     public static int hashCodeForDoubleArray(double[] a) {
95         if (a == null) {
96             return 0;
97         }
98         int result = 0;
99         long temp;
100         for (int i = 0; i < a.length; i++) {
101             temp = Double.doubleToLongBits(a[i]);
102             result = (int) (temp ^ (temp >>> 32));
103         }
104         return result;
105     }
106
107 }
108
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