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: } else {
077: // we assume that all other Paint instances implement equals() and
078: // hashCode()...of course that might not be true, but what can we
079: // do about it?
080: result = p.hashCode();
081: }
082: return result;
083: }
084:
085: /**
086: * Returns a hash code for a <code>double[]</code> instance. If the array
087: * is <code>null</code>, this method returns zero.
088: *
089: * @param a the array (<code>null</code> permitted).
090: *
091: * @return The hash code.
092: */
093: public static int hashCodeForDoubleArray(double[] a) {
094: if (a == null) {
095: return 0;
096: }
097: int result = 193;
098: long temp;
099: for (int i = 0; i < a.length; i++) {
100: temp = Double.doubleToLongBits(a[i]);
101: result = 29 * result + (int) (temp ^ (temp >>> 32));
102: }
103: return result;
104: }
105:
106: }
|