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 * SimpleTimePeriod.java
029 * ---------------------
030 * (C) Copyright 2002-2008, by Object Refinery Limited and Contributors.
031 *
032 * Original Author: David Gilbert (for Object Refinery Limited);
033 * Contributor(s): -;
034 *
035 * Changes
036 * -------
037 * 07-Oct-2002 : Added Javadocs (DG);
038 * 10-Jan-2003 : Renamed TimeAllocation --> SimpleTimePeriod (DG);
039 * 13-Mar-2003 : Added equals() method, and Serializable interface (DG);
040 * 21-Oct-2003 : Added hashCode() method (DG);
041 * 27-Jan-2005 : Implemented Comparable, to enable this class to be used
042 * in the TimeTableXYDataset class (DG);
043 * 02-Jun-2008 : Fixed problem with fields being mutable (DG);
044 *
045 */
046
047 package org.jfree.data.time;
048
049 import java.io.Serializable;
050 import java.util.Date;
051
052 /**
053 * An arbitrary period of time, measured to millisecond precision using
054 * <code>java.util.Date</code>.
055 * <p>
056 * This class is intentionally immutable (that is, once constructed, you cannot
057 * alter the start and end attributes).
058 */
059 public class SimpleTimePeriod implements TimePeriod, Comparable, Serializable {
060
061 /** For serialization. */
062 private static final long serialVersionUID = 8684672361131829554L;
063
064 /** The start date/time. */
065 private long start;
066
067 /** The end date/time. */
068 private long end;
069
070 /**
071 * Creates a new time allocation.
072 *
073 * @param start the start date/time in milliseconds.
074 * @param end the end date/time in milliseconds.
075 */
076 public SimpleTimePeriod(long start, long end) {
077 if (start > end) {
078 throw new IllegalArgumentException("Requires start <= end.");
079 }
080 this.start = start;
081 this.end = end;
082 }
083
084 /**
085 * Creates a new time allocation.
086 *
087 * @param start the start date/time (<code>null</code> not permitted).
088 * @param end the end date/time (<code>null</code> not permitted).
089 */
090 public SimpleTimePeriod(Date start, Date end) {
091 this(start.getTime(), end.getTime());
092 }
093
094 /**
095 * Returns the start date/time.
096 *
097 * @return The start date/time (never <code>null</code>).
098 */
099 public Date getStart() {
100 return new Date(this.start);
101 }
102
103 /**
104 * Returns the start date/time in milliseconds.
105 *
106 * @return The start.
107 *
108 * @since 1.0.10.
109 */
110 public long getStartMillis() {
111 return this.start;
112 }
113
114 /**
115 * Returns the end date/time.
116 *
117 * @return The end date/time (never <code>null</code>).
118 */
119 public Date getEnd() {
120 return new Date(this.end);
121 }
122
123 /**
124 * Returns the end date/time in milliseconds.
125 *
126 * @return The end.
127 *
128 * @since 1.0.10.
129 */
130 public long getEndMillis() {
131 return this.end;
132 }
133
134 /**
135 * Tests this time period instance for equality with an arbitrary object.
136 * The object is considered equal if it is an instance of {@link TimePeriod}
137 * and it has the same start and end dates.
138 *
139 * @param obj the other object (<code>null</code> permitted).
140 *
141 * @return A boolean.
142 */
143 public boolean equals(Object obj) {
144 if (obj == this) {
145 return true;
146 }
147 if (!(obj instanceof TimePeriod)) {
148 return false;
149 }
150 TimePeriod that = (TimePeriod) obj;
151 if (!this.getStart().equals(that.getStart())) {
152 return false;
153 }
154 if (!this.getEnd().equals(that.getEnd())) {
155 return false;
156 }
157 return true;
158 }
159
160 /**
161 * Returns an integer that indicates the relative ordering of two
162 * time periods.
163 *
164 * @param obj the object (<code>null</code> not permitted).
165 *
166 * @return An integer.
167 *
168 * @throws ClassCastException if <code>obj</code> is not an instance of
169 * {@link TimePeriod}.
170 */
171 public int compareTo(Object obj) {
172 TimePeriod that = (TimePeriod) obj;
173 long t0 = getStart().getTime();
174 long t1 = getEnd().getTime();
175 long m0 = t0 + (t1 - t0) / 2L;
176 long t2 = that.getStart().getTime();
177 long t3 = that.getEnd().getTime();
178 long m1 = t2 + (t3 - t2) / 2L;
179 if (m0 < m1) {
180 return -1;
181 }
182 else if (m0 > m1) {
183 return 1;
184 }
185 else {
186 if (t0 < t2) {
187 return -1;
188 }
189 else if (t0 > t2) {
190 return 1;
191 }
192 else {
193 if (t1 < t3) {
194 return -1;
195 }
196 else if (t1 > t3) {
197 return 1;
198 }
199 else {
200 return 0;
201 }
202 }
203 }
204 }
205
206 /**
207 * Returns a hash code for this object instance. The approach described by
208 * Joshua Bloch in "Effective Java" has been used here - see:
209 * <p>
210 * <code>http://developer.java.sun.com/
211 * developer/Books/effectivejava/Chapter3.pdf</code>
212 *
213 * @return A hash code.
214 */
215 public int hashCode() {
216 int result = 17;
217 result = 37 * result + (int) this.start;
218 result = 37 * result + (int) this.end;
219 return result;
220 }
221
222 }