001 /* =========================================================== 002 * JFreeChart : a free chart library for the Java(tm) platform 003 * =========================================================== 004 * 005 * (C) Copyright 2000-2006, 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 * RegularTimePeriod.java 029 * ---------------------- 030 * (C) Copyright 2001-2006, by Object Refinery Limited. 031 * 032 * Original Author: David Gilbert (for Object Refinery Limited); 033 * Contributor(s): -; 034 * 035 * $Id: RegularTimePeriod.java,v 1.6.2.2 2006/10/06 14:00:15 mungady Exp $ 036 * 037 * Changes 038 * ------- 039 * 11-Oct-2001 : Version 1 (DG); 040 * 26-Feb-2002 : Changed getStart(), getMiddle() and getEnd() methods to 041 * evaluate with reference to a particular time zone (DG); 042 * 29-May-2002 : Implemented MonthConstants interface, so that these constants 043 * are conveniently available (DG); 044 * 10-Sep-2002 : Added getSerialIndex() method (DG); 045 * 10-Jan-2003 : Renamed TimePeriod --> RegularTimePeriod (DG); 046 * 13-Mar-2003 : Moved to com.jrefinery.data.time package (DG); 047 * 29-Apr-2004 : Changed getMiddleMillisecond() methods to fix bug 943985 (DG); 048 * 25-Nov-2004 : Added utility methods (DG); 049 * ------------- JFREECHART 1.0.x --------------------------------------------- 050 * 06-Oct-2006 : Deprecated the WORKING_CALENDAR field and several methods, 051 * added new peg() method (DG); 052 * 053 */ 054 055 package org.jfree.data.time; 056 057 import java.lang.reflect.Constructor; 058 import java.util.Calendar; 059 import java.util.Date; 060 import java.util.TimeZone; 061 062 import org.jfree.date.MonthConstants; 063 064 /** 065 * An abstract class representing a unit of time. Convenient methods are 066 * provided for calculating the next and previous time periods. Conversion 067 * methods are defined that return the first and last milliseconds of the time 068 * period. The results from these methods are timezone dependent. 069 * <P> 070 * This class is immutable, and all subclasses should be immutable also. 071 */ 072 public abstract class RegularTimePeriod implements TimePeriod, Comparable, 073 MonthConstants { 074 075 /** 076 * Creates a time period that includes the specified millisecond, assuming 077 * the given time zone. 078 * 079 * @param c the time period class. 080 * @param millisecond the time. 081 * @param zone the time zone. 082 * 083 * @return The time period. 084 */ 085 public static RegularTimePeriod createInstance(Class c, Date millisecond, 086 TimeZone zone) { 087 RegularTimePeriod result = null; 088 try { 089 Constructor constructor = c.getDeclaredConstructor( 090 new Class[] {Date.class, TimeZone.class}); 091 result = (RegularTimePeriod) constructor.newInstance( 092 new Object[] {millisecond, zone}); 093 } 094 catch (Exception e) { 095 // do nothing, so null is returned 096 } 097 return result; 098 } 099 100 /** 101 * Returns a subclass of {@link RegularTimePeriod} that is smaller than 102 * the specified class. 103 * 104 * @param c a subclass of {@link RegularTimePeriod}. 105 * 106 * @return A class. 107 */ 108 public static Class downsize(Class c) { 109 if (c.equals(Year.class)) { 110 return Quarter.class; 111 } 112 else if (c.equals(Quarter.class)) { 113 return Month.class; 114 } 115 else if (c.equals(Month.class)) { 116 return Day.class; 117 } 118 else if (c.equals(Day.class)) { 119 return Hour.class; 120 } 121 else if (c.equals(Hour.class)) { 122 return Minute.class; 123 } 124 else if (c.equals(Minute.class)) { 125 return Second.class; 126 } 127 else if (c.equals(Second.class)) { 128 return Millisecond.class; 129 } 130 else { 131 return Millisecond.class; 132 } 133 } 134 135 /** 136 * Returns the time period preceding this one, or <code>null</code> if some 137 * lower limit has been reached. 138 * 139 * @return The previous time period (possibly <code>null</code>). 140 */ 141 public abstract RegularTimePeriod previous(); 142 143 /** 144 * Returns the time period following this one, or <code>null</code> if some 145 * limit has been reached. 146 * 147 * @return The next time period (possibly <code>null</code>). 148 */ 149 public abstract RegularTimePeriod next(); 150 151 /** 152 * Returns a serial index number for the time unit. 153 * 154 * @return The serial index number. 155 */ 156 public abstract long getSerialIndex(); 157 158 ////////////////////////////////////////////////////////////////////////// 159 160 /** 161 * The default time zone. 162 */ 163 public static final TimeZone DEFAULT_TIME_ZONE = TimeZone.getDefault(); 164 165 /** 166 * A working calendar (recycle to avoid unnecessary object creation). 167 * 168 * @deprecated This was a bad idea, don't use it! 169 */ 170 public static final Calendar WORKING_CALENDAR 171 = Calendar.getInstance(DEFAULT_TIME_ZONE); 172 173 /** 174 * Recalculates the start date/time and end date/time for this time period 175 * relative to the supplied calendar (which incorporates a time zone). 176 * 177 * @param calendar the calendar (<code>null</code> not permitted). 178 * 179 * @since 1.0.3 180 */ 181 public abstract void peg(Calendar calendar); 182 183 /** 184 * Returns the date/time that marks the start of the time period. This 185 * method returns a new <code>Date</code> instance every time it is called. 186 * 187 * @return The start date/time. 188 * 189 * @see #getFirstMillisecond() 190 */ 191 public Date getStart() { 192 return new Date(getFirstMillisecond()); 193 } 194 195 /** 196 * Returns the date/time that marks the end of the time period. This 197 * method returns a new <code>Date</code> instance every time it is called. 198 * 199 * @return The end date/time. 200 * 201 * @see #getLastMillisecond() 202 */ 203 public Date getEnd() { 204 return new Date(getLastMillisecond()); 205 } 206 207 /** 208 * Returns the first millisecond of the time period. This will be 209 * determined relative to the time zone specified in the constructor, or 210 * in the calendar instance passed in the most recent call to the 211 * {@link #peg(Calendar)} method. 212 * 213 * @return The first millisecond of the time period. 214 * 215 * @see #getLastMillisecond() 216 */ 217 public abstract long getFirstMillisecond(); 218 219 /** 220 * Returns the first millisecond of the time period, evaluated within a 221 * specific time zone. 222 * 223 * @param zone the time zone (<code>null</code> not permitted). 224 * 225 * @return The first millisecond of the time period. 226 * 227 * @deprecated As of 1.0.3, you should avoid using this method (it creates 228 * a new Calendar instance every time it is called). You are advised 229 * to call {@link #getFirstMillisecond(Calendar)} instead. 230 * 231 * @see #getLastMillisecond(TimeZone) 232 */ 233 public long getFirstMillisecond(TimeZone zone) { 234 Calendar calendar = Calendar.getInstance(zone); 235 return getFirstMillisecond(calendar); 236 } 237 238 /** 239 * Returns the first millisecond of the time period, evaluated using the 240 * supplied calendar (which incorporates a timezone). 241 * 242 * @param calendar the calendar (<code>null</code> not permitted). 243 * 244 * @return The first millisecond of the time period. 245 * 246 * @throws NullPointerException if <code>calendar,/code> is 247 * </code>null</code>. 248 * 249 * @see #getLastMillisecond(Calendar) 250 */ 251 public abstract long getFirstMillisecond(Calendar calendar); 252 253 /** 254 * Returns the last millisecond of the time period. This will be 255 * determined relative to the time zone specified in the constructor, or 256 * in the calendar instance passed in the most recent call to the 257 * {@link #peg(Calendar)} method. 258 * 259 * @return The last millisecond of the time period. 260 * 261 * @see #getFirstMillisecond() 262 */ 263 public abstract long getLastMillisecond(); 264 265 /** 266 * Returns the last millisecond of the time period, evaluated within a 267 * specific time zone. 268 * 269 * @param zone the time zone (<code>null</code> not permitted). 270 * 271 * @return The last millisecond of the time period. 272 * 273 * @deprecated As of 1.0.3, you should avoid using this method (it creates 274 * a new Calendar instance every time it is called). You are advised 275 * to call {@link #getLastMillisecond(Calendar)} instead. 276 * 277 * @see #getFirstMillisecond(TimeZone) 278 */ 279 public long getLastMillisecond(TimeZone zone) { 280 Calendar calendar = Calendar.getInstance(zone); 281 return getLastMillisecond(calendar); 282 } 283 284 /** 285 * Returns the last millisecond of the time period, evaluated using the 286 * supplied calendar (which incorporates a timezone). 287 * 288 * @param calendar the calendar (<code>null</code> not permitted). 289 * 290 * @return The last millisecond of the time period. 291 * 292 * @see #getFirstMillisecond(Calendar) 293 */ 294 public abstract long getLastMillisecond(Calendar calendar); 295 296 /** 297 * Returns the millisecond closest to the middle of the time period. 298 * 299 * @return The middle millisecond. 300 */ 301 public long getMiddleMillisecond() { 302 long m1 = getFirstMillisecond(); 303 long m2 = getLastMillisecond(); 304 return m1 + (m2 - m1) / 2; 305 } 306 307 /** 308 * Returns the millisecond closest to the middle of the time period, 309 * evaluated within a specific time zone. 310 * 311 * @param zone the time zone (<code>null</code> not permitted). 312 * 313 * @return The middle millisecond. 314 * 315 * @deprecated As of 1.0.3, you should avoid using this method (it creates 316 * a new Calendar instance every time it is called). You are advised 317 * to call {@link #getMiddleMillisecond(Calendar)} instead. 318 */ 319 public long getMiddleMillisecond(TimeZone zone) { 320 Calendar calendar = Calendar.getInstance(zone); 321 long m1 = getFirstMillisecond(calendar); 322 long m2 = getLastMillisecond(calendar); 323 return m1 + (m2 - m1) / 2; 324 } 325 326 /** 327 * Returns the millisecond closest to the middle of the time period, 328 * evaluated using the supplied calendar (which incorporates a timezone). 329 * 330 * @param calendar the calendar. 331 * 332 * @return The middle millisecond. 333 */ 334 public long getMiddleMillisecond(Calendar calendar) { 335 long m1 = getFirstMillisecond(calendar); 336 long m2 = getLastMillisecond(calendar); 337 return m1 + (m2 - m1) / 2; 338 } 339 340 /** 341 * Returns a string representation of the time period. 342 * 343 * @return The string. 344 */ 345 public String toString() { 346 return String.valueOf(getStart()); 347 } 348 349 }