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 * RegularTimePeriod.java
029 * ----------------------
030 * (C) Copyright 2001-2007, by Object Refinery Limited.
031 *
032 * Original Author: David Gilbert (for Object Refinery Limited);
033 * Contributor(s): -;
034 *
035 * Changes
036 * -------
037 * 11-Oct-2001 : Version 1 (DG);
038 * 26-Feb-2002 : Changed getStart(), getMiddle() and getEnd() methods to
039 * evaluate with reference to a particular time zone (DG);
040 * 29-May-2002 : Implemented MonthConstants interface, so that these constants
041 * are conveniently available (DG);
042 * 10-Sep-2002 : Added getSerialIndex() method (DG);
043 * 10-Jan-2003 : Renamed TimePeriod --> RegularTimePeriod (DG);
044 * 13-Mar-2003 : Moved to com.jrefinery.data.time package (DG);
045 * 29-Apr-2004 : Changed getMiddleMillisecond() methods to fix bug 943985 (DG);
046 * 25-Nov-2004 : Added utility methods (DG);
047 * ------------- JFREECHART 1.0.x ---------------------------------------------
048 * 06-Oct-2006 : Deprecated the WORKING_CALENDAR field and several methods,
049 * added new peg() method (DG);
050 *
051 */
052
053 package org.jfree.data.time;
054
055 import java.lang.reflect.Constructor;
056 import java.util.Calendar;
057 import java.util.Date;
058 import java.util.TimeZone;
059
060 import org.jfree.date.MonthConstants;
061
062 /**
063 * An abstract class representing a unit of time. Convenient methods are
064 * provided for calculating the next and previous time periods. Conversion
065 * methods are defined that return the first and last milliseconds of the time
066 * period. The results from these methods are timezone dependent.
067 * <P>
068 * This class is immutable, and all subclasses should be immutable also.
069 */
070 public abstract class RegularTimePeriod implements TimePeriod, Comparable,
071 MonthConstants {
072
073 /**
074 * Creates a time period that includes the specified millisecond, assuming
075 * the given time zone.
076 *
077 * @param c the time period class.
078 * @param millisecond the time.
079 * @param zone the time zone.
080 *
081 * @return The time period.
082 */
083 public static RegularTimePeriod createInstance(Class c, Date millisecond,
084 TimeZone zone) {
085 RegularTimePeriod result = null;
086 try {
087 Constructor constructor = c.getDeclaredConstructor(
088 new Class[] {Date.class, TimeZone.class});
089 result = (RegularTimePeriod) constructor.newInstance(
090 new Object[] {millisecond, zone});
091 }
092 catch (Exception e) {
093 // do nothing, so null is returned
094 }
095 return result;
096 }
097
098 /**
099 * Returns a subclass of {@link RegularTimePeriod} that is smaller than
100 * the specified class.
101 *
102 * @param c a subclass of {@link RegularTimePeriod}.
103 *
104 * @return A class.
105 */
106 public static Class downsize(Class c) {
107 if (c.equals(Year.class)) {
108 return Quarter.class;
109 }
110 else if (c.equals(Quarter.class)) {
111 return Month.class;
112 }
113 else if (c.equals(Month.class)) {
114 return Day.class;
115 }
116 else if (c.equals(Day.class)) {
117 return Hour.class;
118 }
119 else if (c.equals(Hour.class)) {
120 return Minute.class;
121 }
122 else if (c.equals(Minute.class)) {
123 return Second.class;
124 }
125 else if (c.equals(Second.class)) {
126 return Millisecond.class;
127 }
128 else {
129 return Millisecond.class;
130 }
131 }
132
133 /**
134 * Returns the time period preceding this one, or <code>null</code> if some
135 * lower limit has been reached.
136 *
137 * @return The previous time period (possibly <code>null</code>).
138 */
139 public abstract RegularTimePeriod previous();
140
141 /**
142 * Returns the time period following this one, or <code>null</code> if some
143 * limit has been reached.
144 *
145 * @return The next time period (possibly <code>null</code>).
146 */
147 public abstract RegularTimePeriod next();
148
149 /**
150 * Returns a serial index number for the time unit.
151 *
152 * @return The serial index number.
153 */
154 public abstract long getSerialIndex();
155
156 //////////////////////////////////////////////////////////////////////////
157
158 /**
159 * The default time zone.
160 */
161 public static final TimeZone DEFAULT_TIME_ZONE = TimeZone.getDefault();
162
163 /**
164 * A working calendar (recycle to avoid unnecessary object creation).
165 *
166 * @deprecated This was a bad idea, don't use it!
167 */
168 public static final Calendar WORKING_CALENDAR
169 = Calendar.getInstance(DEFAULT_TIME_ZONE);
170
171 /**
172 * Recalculates the start date/time and end date/time for this time period
173 * relative to the supplied calendar (which incorporates a time zone).
174 *
175 * @param calendar the calendar (<code>null</code> not permitted).
176 *
177 * @since 1.0.3
178 */
179 public abstract void peg(Calendar calendar);
180
181 /**
182 * Returns the date/time that marks the start of the time period. This
183 * method returns a new <code>Date</code> instance every time it is called.
184 *
185 * @return The start date/time.
186 *
187 * @see #getFirstMillisecond()
188 */
189 public Date getStart() {
190 return new Date(getFirstMillisecond());
191 }
192
193 /**
194 * Returns the date/time that marks the end of the time period. This
195 * method returns a new <code>Date</code> instance every time it is called.
196 *
197 * @return The end date/time.
198 *
199 * @see #getLastMillisecond()
200 */
201 public Date getEnd() {
202 return new Date(getLastMillisecond());
203 }
204
205 /**
206 * Returns the first millisecond of the time period. This will be
207 * determined relative to the time zone specified in the constructor, or
208 * in the calendar instance passed in the most recent call to the
209 * {@link #peg(Calendar)} method.
210 *
211 * @return The first millisecond of the time period.
212 *
213 * @see #getLastMillisecond()
214 */
215 public abstract long getFirstMillisecond();
216
217 /**
218 * Returns the first millisecond of the time period, evaluated within a
219 * specific time zone.
220 *
221 * @param zone the time zone (<code>null</code> not permitted).
222 *
223 * @return The first millisecond of the time period.
224 *
225 * @deprecated As of 1.0.3, you should avoid using this method (it creates
226 * a new Calendar instance every time it is called). You are advised
227 * to call {@link #getFirstMillisecond(Calendar)} instead.
228 *
229 * @see #getLastMillisecond(TimeZone)
230 */
231 public long getFirstMillisecond(TimeZone zone) {
232 Calendar calendar = Calendar.getInstance(zone);
233 return getFirstMillisecond(calendar);
234 }
235
236 /**
237 * Returns the first millisecond of the time period, evaluated using the
238 * supplied calendar (which incorporates a timezone).
239 *
240 * @param calendar the calendar (<code>null</code> not permitted).
241 *
242 * @return The first millisecond of the time period.
243 *
244 * @throws NullPointerException if <code>calendar,/code> is
245 * </code>null</code>.
246 *
247 * @see #getLastMillisecond(Calendar)
248 */
249 public abstract long getFirstMillisecond(Calendar calendar);
250
251 /**
252 * Returns the last millisecond of the time period. This will be
253 * determined relative to the time zone specified in the constructor, or
254 * in the calendar instance passed in the most recent call to the
255 * {@link #peg(Calendar)} method.
256 *
257 * @return The last millisecond of the time period.
258 *
259 * @see #getFirstMillisecond()
260 */
261 public abstract long getLastMillisecond();
262
263 /**
264 * Returns the last millisecond of the time period, evaluated within a
265 * specific time zone.
266 *
267 * @param zone the time zone (<code>null</code> not permitted).
268 *
269 * @return The last millisecond of the time period.
270 *
271 * @deprecated As of 1.0.3, you should avoid using this method (it creates
272 * a new Calendar instance every time it is called). You are advised
273 * to call {@link #getLastMillisecond(Calendar)} instead.
274 *
275 * @see #getFirstMillisecond(TimeZone)
276 */
277 public long getLastMillisecond(TimeZone zone) {
278 Calendar calendar = Calendar.getInstance(zone);
279 return getLastMillisecond(calendar);
280 }
281
282 /**
283 * Returns the last millisecond of the time period, evaluated using the
284 * supplied calendar (which incorporates a timezone).
285 *
286 * @param calendar the calendar (<code>null</code> not permitted).
287 *
288 * @return The last millisecond of the time period.
289 *
290 * @see #getFirstMillisecond(Calendar)
291 */
292 public abstract long getLastMillisecond(Calendar calendar);
293
294 /**
295 * Returns the millisecond closest to the middle of the time period.
296 *
297 * @return The middle millisecond.
298 */
299 public long getMiddleMillisecond() {
300 long m1 = getFirstMillisecond();
301 long m2 = getLastMillisecond();
302 return m1 + (m2 - m1) / 2;
303 }
304
305 /**
306 * Returns the millisecond closest to the middle of the time period,
307 * evaluated within a specific time zone.
308 *
309 * @param zone the time zone (<code>null</code> not permitted).
310 *
311 * @return The middle millisecond.
312 *
313 * @deprecated As of 1.0.3, you should avoid using this method (it creates
314 * a new Calendar instance every time it is called). You are advised
315 * to call {@link #getMiddleMillisecond(Calendar)} instead.
316 */
317 public long getMiddleMillisecond(TimeZone zone) {
318 Calendar calendar = Calendar.getInstance(zone);
319 long m1 = getFirstMillisecond(calendar);
320 long m2 = getLastMillisecond(calendar);
321 return m1 + (m2 - m1) / 2;
322 }
323
324 /**
325 * Returns the millisecond closest to the middle of the time period,
326 * evaluated using the supplied calendar (which incorporates a timezone).
327 *
328 * @param calendar the calendar.
329 *
330 * @return The middle millisecond.
331 */
332 public long getMiddleMillisecond(Calendar calendar) {
333 long m1 = getFirstMillisecond(calendar);
334 long m2 = getLastMillisecond(calendar);
335 return m1 + (m2 - m1) / 2;
336 }
337
338 /**
339 * Returns a string representation of the time period.
340 *
341 * @return The string.
342 */
343 public String toString() {
344 return String.valueOf(getStart());
345 }
346
347 }