001/* ===========================================================
002 * JFreeChart : a free chart library for the Java(tm) platform
003 * ===========================================================
004 *
005 * (C) Copyright 2000-2011, 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 * [Oracle and Java are registered trademarks of Oracle and/or its affiliates. 
025 * Other names may be trademarks of their respective owners.]
026 *
027 * -----------------------
028 * TimeSeriesDataItem.java
029 * -----------------------
030 * (C) Copyright 2001-2009, by Object Refinery Limited.
031 *
032 * Original Author:  David Gilbert (for Object Refinery Limited);
033 * Contributor(s):   -;
034 *
035 * Changes
036 * -------
037 * 11-Oct-2001 : Version 1 (DG);
038 * 15-Nov-2001 : Updated Javadoc comments (DG);
039 * 29-Nov-2001 : Added cloning (DG);
040 * 24-Jun-2002 : Removed unnecessary import (DG);
041 * 07-Oct-2002 : Fixed errors reported by Checkstyle (DG);
042 * 13-Mar-2003 : Renamed TimeSeriesDataPair --> TimeSeriesDataItem, moved to
043 *               com.jrefinery.data.time package, implemented Serializable (DG)
044 * ------------- JFREECHART 1.0.x ---------------------------------------------
045 * 09-Jun-2009 : Tidied up equals() (DG);
046 */
047
048package org.jfree.data.time;
049
050import java.io.Serializable;
051import org.jfree.util.ObjectUtilities;
052
053/**
054 * Represents one data item in a time series.
055 * <P>
056 * The time period can be any of the following:
057 * <ul>
058 * <li>{@link Year}</li>
059 * <li>{@link Quarter}</li>
060 * <li>{@link Month}</li>
061 * <li>{@link Week}</li>
062 * <li>{@link Day}</li>
063 * <li>{@link Hour}</li>
064 * <li>{@link Minute}</li>
065 * <li>{@link Second}</li>
066 * <li>{@link Millisecond}</li>
067 * <li>{@link FixedMillisecond}</li>
068 * </ul>
069 *
070 * The time period is an immutable property of the data item.  Data items will
071 * often be sorted within a list, and allowing the time period to be changed
072 * could destroy the sort order.
073 * <P>
074 * Implements the <code>Comparable</code> interface so that standard Java
075 * sorting can be used to keep the data items in order.
076 *
077 */
078public class TimeSeriesDataItem implements Cloneable, Comparable, Serializable {
079
080    /** For serialization. */
081    private static final long serialVersionUID = -2235346966016401302L;
082
083    /** The time period. */
084    private RegularTimePeriod period;
085
086    /** The value associated with the time period. */
087    private Number value;
088
089    /**
090     * Constructs a new data item that associates a value with a time period.
091     *
092     * @param period  the time period (<code>null</code> not permitted).
093     * @param value  the value (<code>null</code> permitted).
094     */
095    public TimeSeriesDataItem(RegularTimePeriod period, Number value) {
096        if (period == null) {
097            throw new IllegalArgumentException("Null 'period' argument.");
098        }
099        this.period = period;
100        this.value = value;
101    }
102
103    /**
104     * Constructs a new data item that associates a value with a time period.
105     *
106     * @param period  the time period (<code>null</code> not permitted).
107     * @param value  the value associated with the time period.
108     */
109    public TimeSeriesDataItem(RegularTimePeriod period, double value) {
110        this(period, new Double(value));
111    }
112
113    /**
114     * Returns the time period.
115     *
116     * @return The time period (never <code>null</code>).
117     */
118    public RegularTimePeriod getPeriod() {
119        return this.period;
120    }
121
122    /**
123     * Returns the value.
124     *
125     * @return The value (<code>null</code> possible).
126     *
127     * @see #setValue(java.lang.Number)
128     */
129    public Number getValue() {
130        return this.value;
131    }
132
133    /**
134     * Sets the value for this data item.
135     *
136     * @param value  the value (<code>null</code> permitted).
137     *
138     * @see #getValue()
139     */
140    public void setValue(Number value) {
141        this.value = value;
142    }
143
144    /**
145     * Tests this object for equality with an arbitrary object.
146     *
147     * @param obj  the other object (<code>null</code> permitted).
148     *
149     * @return A boolean.
150     */
151    public boolean equals(Object obj) {
152        if (this == obj) {
153            return true;
154        }
155        if (!(obj instanceof TimeSeriesDataItem)) {
156            return false;
157        }
158        TimeSeriesDataItem that = (TimeSeriesDataItem) obj;
159        if (!ObjectUtilities.equal(this.period, that.period)) {
160            return false;
161        }
162        if (!ObjectUtilities.equal(this.value, that.value)) {
163            return false;
164        }
165        return true;
166    }
167
168    /**
169     * Returns a hash code.
170     *
171     * @return A hash code.
172     */
173    public int hashCode() {
174        int result;
175        result = (this.period != null ? this.period.hashCode() : 0);
176        result = 29 * result + (this.value != null ? this.value.hashCode() : 0);
177        return result;
178    }
179
180    /**
181     * Returns an integer indicating the order of this data pair object
182     * relative to another object.
183     * <P>
184     * For the order we consider only the timing:
185     * negative == before, zero == same, positive == after.
186     *
187     * @param o1  The object being compared to.
188     *
189     * @return An integer indicating the order of the data item object
190     *         relative to another object.
191     */
192    public int compareTo(Object o1) {
193
194        int result;
195
196        // CASE 1 : Comparing to another TimeSeriesDataItem object
197        // -------------------------------------------------------
198        if (o1 instanceof TimeSeriesDataItem) {
199            TimeSeriesDataItem datapair = (TimeSeriesDataItem) o1;
200            result = getPeriod().compareTo(datapair.getPeriod());
201        }
202
203        // CASE 2 : Comparing to a general object
204        // ---------------------------------------------
205        else {
206            // consider time periods to be ordered after general objects
207            result = 1;
208        }
209
210        return result;
211
212    }
213
214    /**
215     * Clones the data item.  Note: there is no need to clone the period or
216     * value since they are immutable classes.
217     *
218     * @return A clone of the data item.
219     */
220    public Object clone() {
221        Object clone = null;
222        try {
223            clone = super.clone();
224        }
225        catch (CloneNotSupportedException e) { // won't get here...
226            e.printStackTrace();
227        }
228        return clone;
229    }
230
231}