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 }