001/* ===========================================================
002 * JFreeChart : a free chart library for the Java(tm) platform
003 * ===========================================================
004 *
005 * (C) Copyright 2000-2008, 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 * TimeSeriesDataItem.java
029 * -----------------------
030 * (C) Copyright 2001-2008, 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 */
045
046package org.jfree.data.time;
047
048import java.io.Serializable;
049
050/**
051 * Represents one data item in a time series.
052 * <P>
053 * The time period can be any of the following:
054 * <ul>
055 * <li>{@link Year}</li>
056 * <li>{@link Quarter}</li>
057 * <li>{@link Month}</li>
058 * <li>{@link Week}</li>
059 * <li>{@link Day}</li>
060 * <li>{@link Hour}</li>
061 * <li>{@link Minute}</li>
062 * <li>{@link Second}</li>
063 * <li>{@link Millisecond}</li>
064 * <li>{@link FixedMillisecond}</li>
065 * </ul>
066 *
067 * The time period is an immutable property of the data item.  Data items will
068 * often be sorted within a list, and allowing the time period to be changed
069 * could destroy the sort order.
070 * <P>
071 * Implements the <code>Comparable</code> interface so that standard Java
072 * sorting can be used to keep the data items in order.
073 *
074 */
075public class TimeSeriesDataItem implements Cloneable, Comparable, Serializable {
076
077    /** For serialization. */
078    private static final long serialVersionUID = -2235346966016401302L;
079
080    /** The time period. */
081    private RegularTimePeriod period;
082
083    /** The value associated with the time period. */
084    private Number value;
085
086    /**
087     * Constructs a new data item that associates a value with a time period.
088     *
089     * @param period  the time period (<code>null</code> not permitted).
090     * @param value  the value (<code>null</code> permitted).
091     */
092    public TimeSeriesDataItem(RegularTimePeriod period, Number value) {
093        if (period == null) {
094            throw new IllegalArgumentException("Null 'period' argument.");
095        }
096        this.period = period;
097        this.value = value;
098    }
099
100    /**
101     * Constructs a new data item that associates a value with a time period.
102     *
103     * @param period  the time period (<code>null</code> not permitted).
104     * @param value  the value associated with the time period.
105     */
106    public TimeSeriesDataItem(RegularTimePeriod period, double value) {
107        this(period, new Double(value));
108    }
109
110    /**
111     * Returns the time period.
112     *
113     * @return The time period (never <code>null</code>).
114     */
115    public RegularTimePeriod getPeriod() {
116        return this.period;
117    }
118
119    /**
120     * Returns the value.
121     *
122     * @return The value (<code>null</code> possible).
123     */
124    public Number getValue() {
125        return this.value;
126    }
127
128    /**
129     * Sets the value for this data item.
130     *
131     * @param value  the value (<code>null</code> permitted).
132     */
133    public void setValue(Number value) {
134        this.value = value;
135    }
136
137    /**
138     * Tests this object for equality with an arbitrary object.
139     *
140     * @param o  the other object.
141     *
142     * @return A boolean.
143     */
144    public boolean equals(Object o) {
145        if (this == o) {
146            return true;
147        }
148        if (!(o instanceof TimeSeriesDataItem)) {
149            return false;
150        }
151        TimeSeriesDataItem timeSeriesDataItem = (TimeSeriesDataItem) o;
152        if (this.period != null) {
153            if (!this.period.equals(timeSeriesDataItem.period)) {
154                return false;
155            }
156        }
157        else if (timeSeriesDataItem.period != null) {
158           return false;
159        }
160
161        if (this.value != null) {
162            if (!this.value.equals(timeSeriesDataItem.value)) {
163                return false;
164            }
165        }
166        else if (timeSeriesDataItem.value != null) {
167            return false;
168        }
169
170        return true;
171    }
172
173    /**
174     * Returns a hash code.
175     *
176     * @return A hash code.
177     */
178    public int hashCode() {
179        int result;
180        result = (this.period != null ? this.period.hashCode() : 0);
181        result = 29 * result + (this.value != null ? this.value.hashCode() : 0);
182        return result;
183    }
184
185    /**
186     * Returns an integer indicating the order of this data pair object
187     * relative to another object.
188     * <P>
189     * For the order we consider only the timing:
190     * negative == before, zero == same, positive == after.
191     *
192     * @param o1  The object being compared to.
193     *
194     * @return An integer indicating the order of the data item object
195     *         relative to another object.
196     */
197    public int compareTo(Object o1) {
198
199        int result;
200
201        // CASE 1 : Comparing to another TimeSeriesDataItem object
202        // -------------------------------------------------------
203        if (o1 instanceof TimeSeriesDataItem) {
204            TimeSeriesDataItem datapair = (TimeSeriesDataItem) o1;
205            result = getPeriod().compareTo(datapair.getPeriod());
206        }
207
208        // CASE 2 : Comparing to a general object
209        // ---------------------------------------------
210        else {
211            // consider time periods to be ordered after general objects
212            result = 1;
213        }
214
215        return result;
216
217    }
218
219    /**
220     * Clones the data item.  Note: there is no need to clone the period or
221     * value since they are immutable classes.
222     *
223     * @return A clone of the data item.
224     */
225    public Object clone() {
226        Object clone = null;
227        try {
228            clone = super.clone();
229        }
230        catch (CloneNotSupportedException e) { // won't get here...
231            e.printStackTrace();
232        }
233        return clone;
234    }
235
236}