001 /* =========================================================== 002 * JFreeChart : a free chart library for the Java(tm) platform 003 * =========================================================== 004 * 005 * (C) Copyright 2000-2007, by Object Refinery Limited and Contributors. 006 * 007 * Project Info: http://www.jfree.org/jfreechart/index.html 008 * 009 * This library is free software; you can redistribute it and/or modify it 010 * under the terms of the GNU Lesser General Public License as published by 011 * the Free Software Foundation; either version 2.1 of the License, or 012 * (at your option) any later version. 013 * 014 * This library is distributed in the hope that it will be useful, but 015 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 016 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 017 * License for more details. 018 * 019 * You should have received a copy of the GNU Lesser General Public 020 * License along with this library; if not, write to the Free Software 021 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, 022 * USA. 023 * 024 * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 025 * in the United States and other countries.] 026 * 027 * ------------------ 028 * HashUtilities.java 029 * ------------------ 030 * (C) Copyright 2006, 2007, by Object Refinery Limited; 031 * 032 * Original Author: David Gilbert (for Object Refinery Limited); 033 * Contributor(s): -; 034 * 035 * $Id: HashUtilities.java,v 1.1.2.2 2007/03/06 16:00:44 mungady Exp $ 036 * 037 * Changes 038 * ------- 039 * 03-Oct-2006 : Version 1 (DG); 040 * 06-Mar-2007 : Fix for hashCodeForDoubleArray() method (DG); 041 * 042 */ 043 044 package org.jfree.chart; 045 046 import java.awt.GradientPaint; 047 import java.awt.Paint; 048 049 /** 050 * Some utility methods for calculating hash codes. 051 * 052 * @since 1.0.3 053 */ 054 public class HashUtilities { 055 056 /** 057 * Returns a hash code for a <code>Paint</code> instance. If 058 * <code>p</code> is <code>null</code>, this method returns zero. 059 * 060 * @param p the paint (<code>null</code> permitted). 061 * 062 * @return The hash code. 063 */ 064 public static int hashCodeForPaint(Paint p) { 065 if (p == null) 066 return 0; 067 int result = 0; 068 // handle GradientPaint as a special case 069 if (p instanceof GradientPaint) { 070 GradientPaint gp = (GradientPaint) p; 071 result = 193; 072 result = 37 * result + gp.getColor1().hashCode(); 073 result = 37 * result + gp.getPoint1().hashCode(); 074 result = 37 * result + gp.getColor2().hashCode(); 075 result = 37 * result + gp.getPoint2().hashCode(); 076 } 077 else { 078 // we assume that all other Paint instances implement equals() and 079 // hashCode()...of course that might not be true, but what can we 080 // do about it? 081 result = p.hashCode(); 082 } 083 return result; 084 } 085 086 /** 087 * Returns a hash code for a <code>double[]</code> instance. If the array 088 * is <code>null</code>, this method returns zero. 089 * 090 * @param a the array (<code>null</code> permitted). 091 * 092 * @return The hash code. 093 */ 094 public static int hashCodeForDoubleArray(double[] a) { 095 if (a == null) { 096 return 0; 097 } 098 int result = 193; 099 long temp; 100 for (int i = 0; i < a.length; i++) { 101 temp = Double.doubleToLongBits(a[i]); 102 result = 29 * result + (int) (temp ^ (temp >>> 32)); 103 } 104 return result; 105 } 106 107 }