Source for org.jfree.data.time.SimpleTimePeriod

   1: /* ===========================================================
   2:  * JFreeChart : a free chart library for the Java(tm) platform
   3:  * ===========================================================
   4:  *
   5:  * (C) Copyright 2000-2007, by Object Refinery Limited and Contributors.
   6:  *
   7:  * Project Info:  http://www.jfree.org/jfreechart/index.html
   8:  *
   9:  * This library is free software; you can redistribute it and/or modify it 
  10:  * under the terms of the GNU Lesser General Public License as published by 
  11:  * the Free Software Foundation; either version 2.1 of the License, or 
  12:  * (at your option) any later version.
  13:  *
  14:  * This library is distributed in the hope that it will be useful, but 
  15:  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 
  16:  * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 
  17:  * License for more details.
  18:  *
  19:  * You should have received a copy of the GNU Lesser General Public
  20:  * License along with this library; if not, write to the Free Software
  21:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, 
  22:  * USA.  
  23:  *
  24:  * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 
  25:  * in the United States and other countries.]
  26:  *
  27:  * ---------------------
  28:  * SimpleTimePeriod.java
  29:  * ---------------------
  30:  * (C) Copyright 2002-2007, by Object Refinery Limited and Contributors.
  31:  *
  32:  * Original Author:  David Gilbert (for Object Refinery Limited);
  33:  * Contributor(s):   -;
  34:  *
  35:  * Changes
  36:  * -------
  37:  * 07-Oct-2002 : Added Javadocs (DG);
  38:  * 10-Jan-2003 : Renamed TimeAllocation --> SimpleTimePeriod (DG);
  39:  * 13-Mar-2003 : Added equals() method, and Serializable interface (DG);
  40:  * 21-Oct-2003 : Added hashCode() method (DG);
  41:  * 27-Jan-2005 : Implemented Comparable, to enable this class to be used
  42:  *               in the TimeTableXYDataset class (DG);
  43:  *
  44:  */
  45: 
  46: package org.jfree.data.time;
  47: 
  48: import java.io.Serializable;
  49: import java.util.Date;
  50: 
  51: /**
  52:  * An arbitrary period of time, measured to millisecond precision using 
  53:  * <code>java.util.Date</code>.
  54:  * <p>
  55:  * This class is intentionally immutable (that is, once constructed, you cannot 
  56:  * alter the start and end attributes).
  57:  */
  58: public class SimpleTimePeriod implements TimePeriod, Comparable, Serializable {
  59: 
  60:     /** For serialization. */
  61:     private static final long serialVersionUID = 8684672361131829554L;
  62:     
  63:     /** The start date/time. */
  64:     private Date start;
  65: 
  66:     /** The end date/time. */
  67:     private Date end;
  68: 
  69:     /**
  70:      * Creates a new time allocation.
  71:      *
  72:      * @param start  the start date/time in milliseconds.
  73:      * @param end  the end date/time in milliseconds.
  74:      */
  75:     public SimpleTimePeriod(long start, long end) {
  76:         this(new Date(start), new Date(end));   
  77:     }
  78:     
  79:     /**
  80:      * Creates a new time allocation.
  81:      *
  82:      * @param start  the start date/time (<code>null</code> not permitted).
  83:      * @param end  the end date/time (<code>null</code> not permitted).
  84:      */
  85:     public SimpleTimePeriod(Date start, Date end) {
  86:         if (start.getTime() > end.getTime()) {
  87:             throw new IllegalArgumentException("Requires end >= start.");
  88:         }
  89:         this.start = start;
  90:         this.end = end;
  91:     }
  92: 
  93:     /**
  94:      * Returns the start date/time.
  95:      *
  96:      * @return The start date/time (never <code>null</code>).
  97:      */
  98:     public Date getStart() {
  99:         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: }