001    /* ===========================================================
002     * JFreeChart : a free chart library for the Java(tm) platform
003     * ===========================================================
004     *
005     * (C) Copyright 2000-2005, 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 2001-2005, by Object Refinery Limited.
031     *
032     * Original Author:  David Gilbert (for Object Refinery Limited);
033     * Contributor(s):   -;
034     *
035     * $Id: TimeSeriesDataItem.java,v 1.5.2.1 2005/10/25 21:35:24 mungady Exp $
036     *
037     * Changes
038     * -------
039     * 11-Oct-2001 : Version 1 (DG);
040     * 15-Nov-2001 : Updated Javadoc comments (DG);
041     * 29-Nov-2001 : Added cloning (DG);
042     * 24-Jun-2002 : Removed unnecessary import (DG);
043     * 07-Oct-2002 : Fixed errors reported by Checkstyle (DG);
044     * 13-Mar-2003 : Renamed TimeSeriesDataPair --> TimeSeriesDataItem, moved to
045     *               com.jrefinery.data.time package, implemented Serializable (DG)
046     */
047    
048    package org.jfree.data.time;
049    
050    import java.io.Serializable;
051    
052    /**
053     * Represents one data item in a time series.
054     * <P>
055     * The time period can be any of the following:
056     * <ul>
057     * <li>{@link Year}</li>
058     * <li>{@link Quarter}</li>
059     * <li>{@link Month}</li>
060     * <li>{@link Week}</li>
061     * <li>{@link Day}</li>
062     * <li>{@link Hour}</li>
063     * <li>{@link Minute}</li>
064     * <li>{@link Second}</li>
065     * <li>{@link Millisecond}</li>
066     * <li>{@link FixedMillisecond}</li>
067     * </ul>
068     *
069     * The time period is an immutable property of the data item.  Data items will
070     * often be sorted within a list, and allowing the time period to be changed
071     * could destroy the sort order.
072     * <P>
073     * Implements the <code>Comparable</code> interface so that standard Java 
074     * sorting can be used to keep the data items in order.
075     *
076     */
077    public class TimeSeriesDataItem implements Cloneable, Comparable, Serializable {
078    
079        /** For serialization. */
080        private static final long serialVersionUID = -2235346966016401302L;
081        
082        /** The time period. */
083        private RegularTimePeriod period;
084    
085        /** The value associated with the time period. */
086        private Number value;
087    
088        /**
089         * Constructs a new data item that associates a value with a time period.
090         *
091         * @param period  the time period (<code>null</code> not permitted).
092         * @param value  the value (<code>null</code> permitted).
093         */
094        public TimeSeriesDataItem(RegularTimePeriod period, Number value) {
095            if (period == null) {
096                throw new IllegalArgumentException("Null 'period' argument.");   
097            }
098            this.period = period;
099            this.value = value;
100        }
101    
102        /**
103         * Constructs a new data item that associates a value with a time period.
104         *
105         * @param period  the time period (<code>null</code> not permitted).
106         * @param value  the value associated with the time period.
107         */
108        public TimeSeriesDataItem(RegularTimePeriod period, double value) {
109            this(period, new Double(value));
110        }
111    
112        /**
113         * Returns the time period.
114         *
115         * @return The time period (never <code>null</code>).
116         */
117        public RegularTimePeriod getPeriod() {
118            return this.period;
119        }
120    
121        /**
122         * Returns the value.
123         *
124         * @return The value (<code>null</code> possible).
125         */
126        public Number getValue() {
127            return this.value;
128        }
129    
130        /**
131         * Sets the value for this data item.
132         *
133         * @param value  the value (<code>null</code> permitted).
134         */
135        public void setValue(Number value) {
136            this.value = value;
137        }
138    
139        /**
140         * Tests this object for equality with an arbitrary object.
141         *
142         * @param o  the other object.
143         *
144         * @return A boolean.
145         */
146        public boolean equals(Object o) {
147            if (this == o) {
148                return true;
149            }
150            if (!(o instanceof TimeSeriesDataItem)) {
151                return false;
152            }
153            TimeSeriesDataItem timeSeriesDataItem = (TimeSeriesDataItem) o;
154            if (this.period != null) {
155                if (!this.period.equals(timeSeriesDataItem.period)) {
156                    return false;
157                }
158            }
159            else if (timeSeriesDataItem.period != null) {
160               return false;
161            }
162            
163            if (this.value != null) {
164                if (!this.value.equals(timeSeriesDataItem.value)) {
165                    return false;
166                }
167            }
168            else if (timeSeriesDataItem.value != null) {
169                return false;
170            }
171    
172            return true;
173        }
174    
175        /**
176         * Returns a hash code.
177         * 
178         * @return A hash code.
179         */
180        public int hashCode() {
181            int result;
182            result = (this.period != null ? this.period.hashCode() : 0);
183            result = 29 * result + (this.value != null ? this.value.hashCode() : 0);
184            return result;
185        }
186    
187        /**
188         * Returns an integer indicating the order of this data pair object
189         * relative to another object.
190         * <P>
191         * For the order we consider only the timing:
192         * negative == before, zero == same, positive == after.
193         *
194         * @param o1  The object being compared to.
195         *
196         * @return An integer indicating the order of the data item object 
197         *         relative to another object.
198         */
199        public int compareTo(Object o1) {
200    
201            int result;
202    
203            // CASE 1 : Comparing to another TimeSeriesDataItem object
204            // -------------------------------------------------------
205            if (o1 instanceof TimeSeriesDataItem) {
206                TimeSeriesDataItem datapair = (TimeSeriesDataItem) o1;
207                result = getPeriod().compareTo(datapair.getPeriod());
208            }
209    
210            // CASE 2 : Comparing to a general object
211            // ---------------------------------------------
212            else {
213                // consider time periods to be ordered after general objects
214                result = 1;
215            }
216    
217            return result;
218    
219        }
220    
221        /**
222         * Clones the data item.  Note: there is no need to clone the period or 
223         * value since they are immutable classes.
224         *
225         * @return A clone of the data item.
226         */
227        public Object clone() {
228            Object clone = null;
229            try {
230                clone = super.clone();
231            }
232            catch (CloneNotSupportedException e) { // won't get here...
233                e.printStackTrace();
234            }
235            return clone;
236        }
237    
238    }