001 /* =========================================================== 002 * JFreeChart : a free chart library for the Java(tm) platform 003 * =========================================================== 004 * 005 * (C) Copyright 2000-2007, 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 2002-2007, 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 * 044 */ 045 046 package org.jfree.data.time; 047 048 import java.io.Serializable; 049 import java.util.Date; 050 051 /** 052 * An arbitrary period of time, measured to millisecond precision using 053 * <code>java.util.Date</code>. 054 * <p> 055 * This class is intentionally immutable (that is, once constructed, you cannot 056 * alter the start and end attributes). 057 */ 058 public class SimpleTimePeriod implements TimePeriod, Comparable, Serializable { 059 060 /** For serialization. */ 061 private static final long serialVersionUID = 8684672361131829554L; 062 063 /** The start date/time. */ 064 private Date start; 065 066 /** The end date/time. */ 067 private Date end; 068 069 /** 070 * Creates a new time allocation. 071 * 072 * @param start the start date/time in milliseconds. 073 * @param end the end date/time in milliseconds. 074 */ 075 public SimpleTimePeriod(long start, long end) { 076 this(new Date(start), new Date(end)); 077 } 078 079 /** 080 * Creates a new time allocation. 081 * 082 * @param start the start date/time (<code>null</code> not permitted). 083 * @param end the end date/time (<code>null</code> not permitted). 084 */ 085 public SimpleTimePeriod(Date start, Date end) { 086 if (start.getTime() > end.getTime()) { 087 throw new IllegalArgumentException("Requires end >= start."); 088 } 089 this.start = start; 090 this.end = end; 091 } 092 093 /** 094 * Returns the start date/time. 095 * 096 * @return The start date/time (never <code>null</code>). 097 */ 098 public Date getStart() { 099 return this.start; 100 } 101 102 /** 103 * Returns the end date/time. 104 * 105 * @return The end date/time (never <code>null</code>). 106 */ 107 public Date getEnd() { 108 return this.end; 109 } 110 111 /** 112 * Tests this time period instance for equality with an arbitrary object. 113 * The object is considered equal if it is an instance of {@link TimePeriod} 114 * and it has the same start and end dates. 115 * 116 * @param obj the other object (<code>null</code> permitted). 117 * 118 * @return A boolean. 119 */ 120 public boolean equals(Object obj) { 121 if (obj == this) { 122 return true; 123 } 124 if (!(obj instanceof TimePeriod)) { 125 return false; 126 } 127 TimePeriod that = (TimePeriod) obj; 128 if (!this.start.equals(that.getStart())) { 129 return false; 130 } 131 if (!this.end.equals(that.getEnd())) { 132 return false; 133 } 134 return true; 135 } 136 137 /** 138 * Returns an integer that indicates the relative ordering of two 139 * time periods. 140 * 141 * @param obj the object (<code>null</code> not permitted). 142 * 143 * @return An integer. 144 * 145 * @throws ClassCastException if <code>obj</code> is not an instance of 146 * {@link TimePeriod}. 147 */ 148 public int compareTo(Object obj) { 149 TimePeriod that = (TimePeriod) obj; 150 long t0 = getStart().getTime(); 151 long t1 = getEnd().getTime(); 152 long m0 = t0 + (t1 - t0) / 2L; 153 long t2 = that.getStart().getTime(); 154 long t3 = that.getEnd().getTime(); 155 long m1 = t2 + (t3 - t2) / 2L; 156 if (m0 < m1) { 157 return -1; 158 } 159 else if (m0 > m1) { 160 return 1; 161 } 162 else { 163 if (t0 < t2) { 164 return -1; 165 } 166 else if (t0 > t2) { 167 return 1; 168 } 169 else { 170 if (t1 < t3) { 171 return -1; 172 } 173 else if (t1 > t3) { 174 return 1; 175 } 176 else { 177 return 0; 178 } 179 } 180 } 181 } 182 183 /** 184 * Returns a hash code for this object instance. The approach described by 185 * Joshua Bloch in "Effective Java" has been used here - see: 186 * <p> 187 * <code>http://developer.java.sun.com/ 188 * developer/Books/effectivejava/Chapter3.pdf</code> 189 * 190 * @return A hash code. 191 */ 192 public int hashCode() { 193 int result = 17; 194 result = 37 * result + this.start.hashCode(); 195 result = 37 * result + this.end.hashCode(); 196 return result; 197 } 198 199 }