Java tutorial
/* =========================================================== * JFreeChart : a free chart library for the Java(tm) platform * =========================================================== * * (C) Copyright 2000-2012, by Object Refinery Limited and Contributors. * * Project Info: http://www.jfree.org/jfreechart/index.html * * This library is free software; you can redistribute it and/or modify it * under the terms of the GNU Lesser General Public License as published by * the Free Software Foundation; either version 2.1 of the License, or * (at your option) any later version. * * This library is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public * License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, * USA. * * [Oracle and Java are registered trademarks of Oracle and/or its affiliates. * Other names may be trademarks of their respective owners.] * * ----------------------------- * MeanAndStandardDeviation.java * ----------------------------- * (C) Copyright 2003-2012, by Object Refinery Limited. * * Original Author: David Gilbert (for Object Refinery Limited); * Contributor(s): -; * * Changes: * -------- * 05-Feb-2002 : Version 1 (DG); * 05-Feb-2005 : Added equals() method and implemented Serializable (DG); * 02-Oct-2007 : Added getMeanValue() and getStandardDeviationValue() methods * for convenience, and toString() method for debugging (DG); * 17-Jun-2012 : Removed JCommon dependencies (DG); * */ package org.jfree.data.statistics; import java.io.Serializable; import org.jfree.chart.util.ObjectUtils; /** * A simple data structure that holds a mean value and a standard deviation * value. This is used in the * {@link org.jfree.data.statistics.DefaultStatisticalCategoryDataset} class. */ public class MeanAndStandardDeviation implements Serializable { /** For serialization. */ private static final long serialVersionUID = 7413468697315721515L; /** The mean. */ private Number mean; /** The standard deviation. */ private Number standardDeviation; /** * Creates a new mean and standard deviation record. * * @param mean the mean. * @param standardDeviation the standard deviation. */ public MeanAndStandardDeviation(double mean, double standardDeviation) { this(new Double(mean), new Double(standardDeviation)); } /** * Creates a new mean and standard deviation record. * * @param mean the mean (<code>null</code> permitted). * @param standardDeviation the standard deviation (<code>null</code> * permitted. */ public MeanAndStandardDeviation(Number mean, Number standardDeviation) { this.mean = mean; this.standardDeviation = standardDeviation; } /** * Returns the mean. * * @return The mean. */ public Number getMean() { return this.mean; } /** * Returns the mean as a double primitive. If the underlying mean is * <code>null</code>, this method will return <code>Double.NaN</code>. * * @return The mean. * * @see #getMean() * * @since 1.0.7 */ public double getMeanValue() { double result = Double.NaN; if (this.mean != null) { result = this.mean.doubleValue(); } return result; } /** * Returns the standard deviation. * * @return The standard deviation. */ public Number getStandardDeviation() { return this.standardDeviation; } /** * Returns the standard deviation as a double primitive. If the underlying * standard deviation is <code>null</code>, this method will return * <code>Double.NaN</code>. * * @return The standard deviation. * * @since 1.0.7 */ public double getStandardDeviationValue() { double result = Double.NaN; if (this.standardDeviation != null) { result = this.standardDeviation.doubleValue(); } return result; } /** * Tests this instance for equality with an arbitrary object. * * @param obj the object (<code>null</code> permitted). * * @return A boolean. */ @Override public boolean equals(Object obj) { if (obj == this) { return true; } if (!(obj instanceof MeanAndStandardDeviation)) { return false; } MeanAndStandardDeviation that = (MeanAndStandardDeviation) obj; if (!ObjectUtils.equal(this.mean, that.mean)) { return false; } if (!ObjectUtils.equal(this.standardDeviation, that.standardDeviation)) { return false; } return true; } /** * Returns a string representing this instance. * * @return A string. * * @since 1.0.7 */ @Override public String toString() { return "[" + this.mean + ", " + this.standardDeviation + "]"; } }