Java tutorial
/* =========================================================== * JFreeChart : a free chart library for the Java(tm) platform * =========================================================== * * (C) Copyright 2000-2013, 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.] * * ----------------------- * TimeSeriesDataItem.java * ----------------------- * (C) Copyright 2001-2013, by Object Refinery Limited. * * Original Author: David Gilbert (for Object Refinery Limited); * Contributor(s): -; * * Changes * ------- * 11-Oct-2001 : Version 1 (DG); * 15-Nov-2001 : Updated Javadoc comments (DG); * 29-Nov-2001 : Added cloning (DG); * 24-Jun-2002 : Removed unnecessary import (DG); * 07-Oct-2002 : Fixed errors reported by Checkstyle (DG); * 13-Mar-2003 : Renamed TimeSeriesDataPair --> TimeSeriesDataItem, moved to * com.jrefinery.data.time package, implemented Serializable (DG) * ------------- JFREECHART 1.0.x --------------------------------------------- * 09-Jun-2009 : Tidied up equals() (DG); * 03-Jul-2013 : Use ParamChecks (DG); * */ package org.jfree.data.time; import java.io.Serializable; import org.jfree.chart.util.ParamChecks; import org.jfree.util.ObjectUtilities; /** * Represents one data item in a time series. * <P> * The time period can be any of the following: * <ul> * <li>{@link Year}</li> * <li>{@link Quarter}</li> * <li>{@link Month}</li> * <li>{@link Week}</li> * <li>{@link Day}</li> * <li>{@link Hour}</li> * <li>{@link Minute}</li> * <li>{@link Second}</li> * <li>{@link Millisecond}</li> * <li>{@link FixedMillisecond}</li> * </ul> * * The time period is an immutable property of the data item. Data items will * often be sorted within a list, and allowing the time period to be changed * could destroy the sort order. * <P> * Implements the <code>Comparable</code> interface so that standard Java * sorting can be used to keep the data items in order. * */ public class TimeSeriesDataItem implements Cloneable, Comparable, Serializable { /** For serialization. */ private static final long serialVersionUID = -2235346966016401302L; /** The time period. */ private RegularTimePeriod period; /** The value associated with the time period. */ private Number value; /** * Constructs a new data item that associates a value with a time period. * * @param period the time period (<code>null</code> not permitted). * @param value the value (<code>null</code> permitted). */ public TimeSeriesDataItem(RegularTimePeriod period, Number value) { ParamChecks.nullNotPermitted(period, "period"); this.period = period; this.value = value; } /** * Constructs a new data item that associates a value with a time period. * * @param period the time period (<code>null</code> not permitted). * @param value the value associated with the time period. */ public TimeSeriesDataItem(RegularTimePeriod period, double value) { this(period, new Double(value)); } /** * Returns the time period. * * @return The time period (never <code>null</code>). */ public RegularTimePeriod getPeriod() { return this.period; } /** * Returns the value. * * @return The value (<code>null</code> possible). * * @see #setValue(java.lang.Number) */ public Number getValue() { return this.value; } /** * Sets the value for this data item. * * @param value the value (<code>null</code> permitted). * * @see #getValue() */ public void setValue(Number value) { this.value = value; } /** * Tests this object for equality with an arbitrary object. * * @param obj the other object (<code>null</code> permitted). * * @return A boolean. */ @Override public boolean equals(Object obj) { if (this == obj) { return true; } if (!(obj instanceof TimeSeriesDataItem)) { return false; } TimeSeriesDataItem that = (TimeSeriesDataItem) obj; if (!ObjectUtilities.equal(this.period, that.period)) { return false; } if (!ObjectUtilities.equal(this.value, that.value)) { return false; } return true; } /** * Returns a hash code. * * @return A hash code. */ @Override public int hashCode() { int result; result = (this.period != null ? this.period.hashCode() : 0); result = 29 * result + (this.value != null ? this.value.hashCode() : 0); return result; } /** * Returns an integer indicating the order of this data pair object * relative to another object. * <P> * For the order we consider only the timing: * negative == before, zero == same, positive == after. * * @param o1 The object being compared to. * * @return An integer indicating the order of the data item object * relative to another object. */ @Override public int compareTo(Object o1) { int result; // CASE 1 : Comparing to another TimeSeriesDataItem object // ------------------------------------------------------- if (o1 instanceof TimeSeriesDataItem) { TimeSeriesDataItem datapair = (TimeSeriesDataItem) o1; result = getPeriod().compareTo(datapair.getPeriod()); } // CASE 2 : Comparing to a general object // --------------------------------------------- else { // consider time periods to be ordered after general objects result = 1; } return result; } /** * Clones the data item. Note: there is no need to clone the period or * value since they are immutable classes. * * @return A clone of the data item. */ @Override public Object clone() { Object clone = null; try { clone = super.clone(); } catch (CloneNotSupportedException e) { // won't get here... e.printStackTrace(); } return clone; } }