001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.lang3.time;
018
019import java.text.ParseException;
020import java.text.ParsePosition;
021import java.util.Calendar;
022import java.util.Date;
023import java.util.Iterator;
024import java.util.Locale;
025import java.util.NoSuchElementException;
026import java.util.TimeZone;
027import java.util.concurrent.TimeUnit;
028
029import org.apache.commons.lang3.Validate;
030
031/**
032 * <p>A suite of utilities surrounding the use of the
033 * {@link java.util.Calendar} and {@link java.util.Date} object.</p>
034 *
035 * <p>DateUtils contains a lot of common methods considering manipulations
036 * of Dates or Calendars. Some methods require some extra explanation.
037 * The truncate, ceiling and round methods could be considered the Math.floor(),
038 * Math.ceil() or Math.round versions for dates
039 * This way date-fields will be ignored in bottom-up order.
040 * As a complement to these methods we've introduced some fragment-methods.
041 * With these methods the Date-fields will be ignored in top-down order.
042 * Since a date without a year is not a valid date, you have to decide in what
043 * kind of date-field you want your result, for instance milliseconds or days.
044 * </p>
045 * <p>
046 * Several methods are provided for adding to {@code Date} objects, of the form
047 * {@code addXXX(Date date, int amount)}. It is important to note these methods
048 * use a {@code Calendar} internally (with default timezone and locale) and may
049 * be affected by changes to daylight saving time (DST).
050 * </p>
051 *
052 * @since 2.0
053 */
054public class DateUtils {
055
056    /**
057     * Number of milliseconds in a standard second.
058     * @since 2.1
059     */
060    public static final long MILLIS_PER_SECOND = 1000;
061    /**
062     * Number of milliseconds in a standard minute.
063     * @since 2.1
064     */
065    public static final long MILLIS_PER_MINUTE = 60 * MILLIS_PER_SECOND;
066    /**
067     * Number of milliseconds in a standard hour.
068     * @since 2.1
069     */
070    public static final long MILLIS_PER_HOUR = 60 * MILLIS_PER_MINUTE;
071    /**
072     * Number of milliseconds in a standard day.
073     * @since 2.1
074     */
075    public static final long MILLIS_PER_DAY = 24 * MILLIS_PER_HOUR;
076
077    /**
078     * This is half a month, so this represents whether a date is in the top
079     * or bottom half of the month.
080     */
081    public static final int SEMI_MONTH = 1001;
082
083    private static final int[][] fields = {
084            {Calendar.MILLISECOND},
085            {Calendar.SECOND},
086            {Calendar.MINUTE},
087            {Calendar.HOUR_OF_DAY, Calendar.HOUR},
088            {Calendar.DATE, Calendar.DAY_OF_MONTH, Calendar.AM_PM
089                /* Calendar.DAY_OF_YEAR, Calendar.DAY_OF_WEEK, Calendar.DAY_OF_WEEK_IN_MONTH */
090            },
091            {Calendar.MONTH, DateUtils.SEMI_MONTH},
092            {Calendar.YEAR},
093            {Calendar.ERA}};
094
095    /**
096     * A week range, starting on Sunday.
097     */
098    public static final int RANGE_WEEK_SUNDAY = 1;
099    /**
100     * A week range, starting on Monday.
101     */
102    public static final int RANGE_WEEK_MONDAY = 2;
103    /**
104     * A week range, starting on the day focused.
105     */
106    public static final int RANGE_WEEK_RELATIVE = 3;
107    /**
108     * A week range, centered around the day focused.
109     */
110    public static final int RANGE_WEEK_CENTER = 4;
111    /**
112     * A month range, the week starting on Sunday.
113     */
114    public static final int RANGE_MONTH_SUNDAY = 5;
115    /**
116     * A month range, the week starting on Monday.
117     */
118    public static final int RANGE_MONTH_MONDAY = 6;
119
120    /**
121     * Calendar modification types.
122     */
123    private enum ModifyType {
124        /**
125         * Truncation.
126         */
127        TRUNCATE,
128
129        /**
130         * Rounding.
131         */
132        ROUND,
133
134        /**
135         * Ceiling.
136         */
137        CEILING
138    }
139
140    /**
141     * <p>{@code DateUtils} instances should NOT be constructed in
142     * standard programming. Instead, the static methods on the class should
143     * be used, such as {@code DateUtils.parseDate(str);}.</p>
144     *
145     * <p>This constructor is public to permit tools that require a JavaBean
146     * instance to operate.</p>
147     */
148    public DateUtils() {
149        super();
150    }
151
152    //-----------------------------------------------------------------------
153    /**
154     * <p>Checks if two date objects are on the same day ignoring time.</p>
155     *
156     * <p>28 Mar 2002 13:45 and 28 Mar 2002 06:01 would return true.
157     * 28 Mar 2002 13:45 and 12 Mar 2002 13:45 would return false.
158     * </p>
159     *
160     * @param date1  the first date, not altered, not null
161     * @param date2  the second date, not altered, not null
162     * @return true if they represent the same day
163     * @throws IllegalArgumentException if either date is <code>null</code>
164     * @since 2.1
165     */
166    public static boolean isSameDay(final Date date1, final Date date2) {
167        if (date1 == null || date2 == null) {
168            throw new IllegalArgumentException("The date must not be null");
169        }
170        final Calendar cal1 = Calendar.getInstance();
171        cal1.setTime(date1);
172        final Calendar cal2 = Calendar.getInstance();
173        cal2.setTime(date2);
174        return isSameDay(cal1, cal2);
175    }
176
177    /**
178     * <p>Checks if two calendar objects are on the same day ignoring time.</p>
179     *
180     * <p>28 Mar 2002 13:45 and 28 Mar 2002 06:01 would return true.
181     * 28 Mar 2002 13:45 and 12 Mar 2002 13:45 would return false.
182     * </p>
183     *
184     * @param cal1  the first calendar, not altered, not null
185     * @param cal2  the second calendar, not altered, not null
186     * @return true if they represent the same day
187     * @throws IllegalArgumentException if either calendar is <code>null</code>
188     * @since 2.1
189     */
190    public static boolean isSameDay(final Calendar cal1, final Calendar cal2) {
191        if (cal1 == null || cal2 == null) {
192            throw new IllegalArgumentException("The date must not be null");
193        }
194        return cal1.get(Calendar.ERA) == cal2.get(Calendar.ERA) &&
195                cal1.get(Calendar.YEAR) == cal2.get(Calendar.YEAR) &&
196                cal1.get(Calendar.DAY_OF_YEAR) == cal2.get(Calendar.DAY_OF_YEAR);
197    }
198
199    //-----------------------------------------------------------------------
200    /**
201     * <p>Checks if two date objects represent the same instant in time.</p>
202     *
203     * <p>This method compares the long millisecond time of the two objects.</p>
204     *
205     * @param date1  the first date, not altered, not null
206     * @param date2  the second date, not altered, not null
207     * @return true if they represent the same millisecond instant
208     * @throws IllegalArgumentException if either date is <code>null</code>
209     * @since 2.1
210     */
211    public static boolean isSameInstant(final Date date1, final Date date2) {
212        if (date1 == null || date2 == null) {
213            throw new IllegalArgumentException("The date must not be null");
214        }
215        return date1.getTime() == date2.getTime();
216    }
217
218    /**
219     * <p>Checks if two calendar objects represent the same instant in time.</p>
220     *
221     * <p>This method compares the long millisecond time of the two objects.</p>
222     *
223     * @param cal1  the first calendar, not altered, not null
224     * @param cal2  the second calendar, not altered, not null
225     * @return true if they represent the same millisecond instant
226     * @throws IllegalArgumentException if either date is <code>null</code>
227     * @since 2.1
228     */
229    public static boolean isSameInstant(final Calendar cal1, final Calendar cal2) {
230        if (cal1 == null || cal2 == null) {
231            throw new IllegalArgumentException("The date must not be null");
232        }
233        return cal1.getTime().getTime() == cal2.getTime().getTime();
234    }
235
236    //-----------------------------------------------------------------------
237    /**
238     * <p>Checks if two calendar objects represent the same local time.</p>
239     *
240     * <p>This method compares the values of the fields of the two objects.
241     * In addition, both calendars must be the same of the same type.</p>
242     *
243     * @param cal1  the first calendar, not altered, not null
244     * @param cal2  the second calendar, not altered, not null
245     * @return true if they represent the same millisecond instant
246     * @throws IllegalArgumentException if either date is <code>null</code>
247     * @since 2.1
248     */
249    public static boolean isSameLocalTime(final Calendar cal1, final Calendar cal2) {
250        if (cal1 == null || cal2 == null) {
251            throw new IllegalArgumentException("The date must not be null");
252        }
253        return cal1.get(Calendar.MILLISECOND) == cal2.get(Calendar.MILLISECOND) &&
254                cal1.get(Calendar.SECOND) == cal2.get(Calendar.SECOND) &&
255                cal1.get(Calendar.MINUTE) == cal2.get(Calendar.MINUTE) &&
256                cal1.get(Calendar.HOUR_OF_DAY) == cal2.get(Calendar.HOUR_OF_DAY) &&
257                cal1.get(Calendar.DAY_OF_YEAR) == cal2.get(Calendar.DAY_OF_YEAR) &&
258                cal1.get(Calendar.YEAR) == cal2.get(Calendar.YEAR) &&
259                cal1.get(Calendar.ERA) == cal2.get(Calendar.ERA) &&
260                cal1.getClass() == cal2.getClass();
261    }
262
263    //-----------------------------------------------------------------------
264    /**
265     * <p>Parses a string representing a date by trying a variety of different parsers.</p>
266     *
267     * <p>The parse will try each parse pattern in turn.
268     * A parse is only deemed successful if it parses the whole of the input string.
269     * If no parse patterns match, a ParseException is thrown.</p>
270     * The parser will be lenient toward the parsed date.
271     *
272     * @param str  the date to parse, not null
273     * @param parsePatterns  the date format patterns to use, see SimpleDateFormat, not null
274     * @return the parsed date
275     * @throws IllegalArgumentException if the date string or pattern array is null
276     * @throws ParseException if none of the date patterns were suitable (or there were none)
277     */
278    public static Date parseDate(final String str, final String... parsePatterns) throws ParseException {
279        return parseDate(str, null, parsePatterns);
280    }
281
282    //-----------------------------------------------------------------------
283    /**
284     * <p>Parses a string representing a date by trying a variety of different parsers,
285     * using the default date format symbols for the given locale.</p>
286     *
287     * <p>The parse will try each parse pattern in turn.
288     * A parse is only deemed successful if it parses the whole of the input string.
289     * If no parse patterns match, a ParseException is thrown.</p>
290     * The parser will be lenient toward the parsed date.
291     *
292     * @param str  the date to parse, not null
293     * @param locale the locale whose date format symbols should be used. If <code>null</code>,
294     * the system locale is used (as per {@link #parseDate(String, String...)}).
295     * @param parsePatterns  the date format patterns to use, see SimpleDateFormat, not null
296     * @return the parsed date
297     * @throws IllegalArgumentException if the date string or pattern array is null
298     * @throws ParseException if none of the date patterns were suitable (or there were none)
299     * @since 3.2
300     */
301    public static Date parseDate(final String str, final Locale locale, final String... parsePatterns) throws ParseException {
302        return parseDateWithLeniency(str, locale, parsePatterns, true);
303    }
304
305  //-----------------------------------------------------------------------
306    /**
307     * <p>Parses a string representing a date by trying a variety of different parsers.</p>
308     *
309     * <p>The parse will try each parse pattern in turn.
310     * A parse is only deemed successful if it parses the whole of the input string.
311     * If no parse patterns match, a ParseException is thrown.</p>
312     * The parser parses strictly - it does not allow for dates such as "February 942, 1996".
313     *
314     * @param str  the date to parse, not null
315     * @param parsePatterns  the date format patterns to use, see SimpleDateFormat, not null
316     * @return the parsed date
317     * @throws IllegalArgumentException if the date string or pattern array is null
318     * @throws ParseException if none of the date patterns were suitable
319     * @since 2.5
320     */
321    public static Date parseDateStrictly(final String str, final String... parsePatterns) throws ParseException {
322        return parseDateStrictly(str, null, parsePatterns);
323    }
324
325    /**
326     * <p>Parses a string representing a date by trying a variety of different parsers,
327     * using the default date format symbols for the given locale..</p>
328     *
329     * <p>The parse will try each parse pattern in turn.
330     * A parse is only deemed successful if it parses the whole of the input string.
331     * If no parse patterns match, a ParseException is thrown.</p>
332     * The parser parses strictly - it does not allow for dates such as "February 942, 1996".
333     *
334     * @param str  the date to parse, not null
335     * @param locale the locale whose date format symbols should be used. If <code>null</code>,
336     * the system locale is used (as per {@link #parseDateStrictly(String, String...)}).
337     * @param parsePatterns  the date format patterns to use, see SimpleDateFormat, not null
338     * @return the parsed date
339     * @throws IllegalArgumentException if the date string or pattern array is null
340     * @throws ParseException if none of the date patterns were suitable
341     * @since 3.2
342     */
343    public static Date parseDateStrictly(final String str, final Locale locale, final String... parsePatterns) throws ParseException {
344        return parseDateWithLeniency(str, locale, parsePatterns, false);
345    }
346
347    /**
348     * <p>Parses a string representing a date by trying a variety of different parsers.</p>
349     *
350     * <p>The parse will try each parse pattern in turn.
351     * A parse is only deemed successful if it parses the whole of the input string.
352     * If no parse patterns match, a ParseException is thrown.</p>
353     *
354     * @param str  the date to parse, not null
355     * @param locale the locale to use when interpretting the pattern, can be null in which
356     * case the default system locale is used
357     * @param parsePatterns  the date format patterns to use, see SimpleDateFormat, not null
358     * @param lenient Specify whether or not date/time parsing is to be lenient.
359     * @return the parsed date
360     * @throws IllegalArgumentException if the date string or pattern array is null
361     * @throws ParseException if none of the date patterns were suitable
362     * @see java.util.Calendar#isLenient()
363     */
364    private static Date parseDateWithLeniency(
365            final String str, final Locale locale, final String[] parsePatterns, final boolean lenient) throws ParseException {
366        if (str == null || parsePatterns == null) {
367            throw new IllegalArgumentException("Date and Patterns must not be null");
368        }
369
370        final TimeZone tz = TimeZone.getDefault();
371        final Locale lcl = locale==null ?Locale.getDefault() : locale;
372        final ParsePosition pos = new ParsePosition(0);
373        final Calendar calendar = Calendar.getInstance(tz, lcl);
374        calendar.setLenient(lenient);
375
376        for (final String parsePattern : parsePatterns) {
377            final FastDateParser fdp = new FastDateParser(parsePattern, tz, lcl);
378            calendar.clear();
379            try {
380                if (fdp.parse(str, pos, calendar) && pos.getIndex()==str.length()) {
381                    return calendar.getTime();
382                }
383            } catch(final IllegalArgumentException ignore) {
384                // leniency is preventing calendar from being set
385            }
386            pos.setIndex(0);
387        }
388        throw new ParseException("Unable to parse the date: " + str, -1);
389    }
390
391    //-----------------------------------------------------------------------
392    /**
393     * Adds a number of years to a date returning a new object.
394     * The original {@code Date} is unchanged.
395     *
396     * @param date  the date, not null
397     * @param amount  the amount to add, may be negative
398     * @return the new {@code Date} with the amount added
399     * @throws IllegalArgumentException if the date is null
400     */
401    public static Date addYears(final Date date, final int amount) {
402        return add(date, Calendar.YEAR, amount);
403    }
404
405    //-----------------------------------------------------------------------
406    /**
407     * Adds a number of months to a date returning a new object.
408     * The original {@code Date} is unchanged.
409     *
410     * @param date  the date, not null
411     * @param amount  the amount to add, may be negative
412     * @return the new {@code Date} with the amount added
413     * @throws IllegalArgumentException if the date is null
414     */
415    public static Date addMonths(final Date date, final int amount) {
416        return add(date, Calendar.MONTH, amount);
417    }
418
419    //-----------------------------------------------------------------------
420    /**
421     * Adds a number of weeks to a date returning a new object.
422     * The original {@code Date} is unchanged.
423     *
424     * @param date  the date, not null
425     * @param amount  the amount to add, may be negative
426     * @return the new {@code Date} with the amount added
427     * @throws IllegalArgumentException if the date is null
428     */
429    public static Date addWeeks(final Date date, final int amount) {
430        return add(date, Calendar.WEEK_OF_YEAR, amount);
431    }
432
433    //-----------------------------------------------------------------------
434    /**
435     * Adds a number of days to a date returning a new object.
436     * The original {@code Date} is unchanged.
437     *
438     * @param date  the date, not null
439     * @param amount  the amount to add, may be negative
440     * @return the new {@code Date} with the amount added
441     * @throws IllegalArgumentException if the date is null
442     */
443    public static Date addDays(final Date date, final int amount) {
444        return add(date, Calendar.DAY_OF_MONTH, amount);
445    }
446
447    //-----------------------------------------------------------------------
448    /**
449     * Adds a number of hours to a date returning a new object.
450     * The original {@code Date} is unchanged.
451     *
452     * @param date  the date, not null
453     * @param amount  the amount to add, may be negative
454     * @return the new {@code Date} with the amount added
455     * @throws IllegalArgumentException if the date is null
456     */
457    public static Date addHours(final Date date, final int amount) {
458        return add(date, Calendar.HOUR_OF_DAY, amount);
459    }
460
461    //-----------------------------------------------------------------------
462    /**
463     * Adds a number of minutes to a date returning a new object.
464     * The original {@code Date} is unchanged.
465     *
466     * @param date  the date, not null
467     * @param amount  the amount to add, may be negative
468     * @return the new {@code Date} with the amount added
469     * @throws IllegalArgumentException if the date is null
470     */
471    public static Date addMinutes(final Date date, final int amount) {
472        return add(date, Calendar.MINUTE, amount);
473    }
474
475    //-----------------------------------------------------------------------
476    /**
477     * Adds a number of seconds to a date returning a new object.
478     * The original {@code Date} is unchanged.
479     *
480     * @param date  the date, not null
481     * @param amount  the amount to add, may be negative
482     * @return the new {@code Date} with the amount added
483     * @throws IllegalArgumentException if the date is null
484     */
485    public static Date addSeconds(final Date date, final int amount) {
486        return add(date, Calendar.SECOND, amount);
487    }
488
489    //-----------------------------------------------------------------------
490    /**
491     * Adds a number of milliseconds to a date returning a new object.
492     * The original {@code Date} is unchanged.
493     *
494     * @param date  the date, not null
495     * @param amount  the amount to add, may be negative
496     * @return the new {@code Date} with the amount added
497     * @throws IllegalArgumentException if the date is null
498     */
499    public static Date addMilliseconds(final Date date, final int amount) {
500        return add(date, Calendar.MILLISECOND, amount);
501    }
502
503    //-----------------------------------------------------------------------
504    /**
505     * Adds to a date returning a new object.
506     * The original {@code Date} is unchanged.
507     *
508     * @param date  the date, not null
509     * @param calendarField  the calendar field to add to
510     * @param amount  the amount to add, may be negative
511     * @return the new {@code Date} with the amount added
512     * @throws IllegalArgumentException if the date is null
513     */
514    private static Date add(final Date date, final int calendarField, final int amount) {
515        validateDateNotNull(date);
516        final Calendar c = Calendar.getInstance();
517        c.setTime(date);
518        c.add(calendarField, amount);
519        return c.getTime();
520    }
521
522    //-----------------------------------------------------------------------
523    /**
524     * Sets the years field to a date returning a new object.
525     * The original {@code Date} is unchanged.
526     *
527     * @param date  the date, not null
528     * @param amount the amount to set
529     * @return a new {@code Date} set with the specified value
530     * @throws IllegalArgumentException if the date is null
531     * @since 2.4
532     */
533    public static Date setYears(final Date date, final int amount) {
534        return set(date, Calendar.YEAR, amount);
535    }
536
537    //-----------------------------------------------------------------------
538    /**
539     * Sets the months field to a date returning a new object.
540     * The original {@code Date} is unchanged.
541     *
542     * @param date  the date, not null
543     * @param amount the amount to set
544     * @return a new {@code Date} set with the specified value
545     * @throws IllegalArgumentException if the date is null
546     * @since 2.4
547     */
548    public static Date setMonths(final Date date, final int amount) {
549        return set(date, Calendar.MONTH, amount);
550    }
551
552    //-----------------------------------------------------------------------
553    /**
554     * Sets the day of month field to a date returning a new object.
555     * The original {@code Date} is unchanged.
556     *
557     * @param date  the date, not null
558     * @param amount the amount to set
559     * @return a new {@code Date} set with the specified value
560     * @throws IllegalArgumentException if the date is null
561     * @since 2.4
562     */
563    public static Date setDays(final Date date, final int amount) {
564        return set(date, Calendar.DAY_OF_MONTH, amount);
565    }
566
567    //-----------------------------------------------------------------------
568    /**
569     * Sets the hours field to a date returning a new object.  Hours range
570     * from  0-23.
571     * The original {@code Date} is unchanged.
572     *
573     * @param date  the date, not null
574     * @param amount the amount to set
575     * @return a new {@code Date} set with the specified value
576     * @throws IllegalArgumentException if the date is null
577     * @since 2.4
578     */
579    public static Date setHours(final Date date, final int amount) {
580        return set(date, Calendar.HOUR_OF_DAY, amount);
581    }
582
583    //-----------------------------------------------------------------------
584    /**
585     * Sets the minute field to a date returning a new object.
586     * The original {@code Date} is unchanged.
587     *
588     * @param date  the date, not null
589     * @param amount the amount to set
590     * @return a new {@code Date} set with the specified value
591     * @throws IllegalArgumentException if the date is null
592     * @since 2.4
593     */
594    public static Date setMinutes(final Date date, final int amount) {
595        return set(date, Calendar.MINUTE, amount);
596    }
597
598    //-----------------------------------------------------------------------
599    /**
600     * Sets the seconds field to a date returning a new object.
601     * The original {@code Date} is unchanged.
602     *
603     * @param date  the date, not null
604     * @param amount the amount to set
605     * @return a new {@code Date} set with the specified value
606     * @throws IllegalArgumentException if the date is null
607     * @since 2.4
608     */
609    public static Date setSeconds(final Date date, final int amount) {
610        return set(date, Calendar.SECOND, amount);
611    }
612
613    //-----------------------------------------------------------------------
614    /**
615     * Sets the milliseconds field to a date returning a new object.
616     * The original {@code Date} is unchanged.
617     *
618     * @param date  the date, not null
619     * @param amount the amount to set
620     * @return a new {@code Date} set with the specified value
621     * @throws IllegalArgumentException if the date is null
622     * @since 2.4
623     */
624    public static Date setMilliseconds(final Date date, final int amount) {
625        return set(date, Calendar.MILLISECOND, amount);
626    }
627
628    //-----------------------------------------------------------------------
629    /**
630     * Sets the specified field to a date returning a new object.
631     * This does not use a lenient calendar.
632     * The original {@code Date} is unchanged.
633     *
634     * @param date  the date, not null
635     * @param calendarField  the {@code Calendar} field to set the amount to
636     * @param amount the amount to set
637     * @return a new {@code Date} set with the specified value
638     * @throws IllegalArgumentException if the date is null
639     * @since 2.4
640     */
641    private static Date set(final Date date, final int calendarField, final int amount) {
642        validateDateNotNull(date);
643        // getInstance() returns a new object, so this method is thread safe.
644        final Calendar c = Calendar.getInstance();
645        c.setLenient(false);
646        c.setTime(date);
647        c.set(calendarField, amount);
648        return c.getTime();
649    }
650
651    //-----------------------------------------------------------------------
652    /**
653     * Converts a {@code Date} into a {@code Calendar}.
654     *
655     * @param date the date to convert to a Calendar
656     * @return the created Calendar
657     * @throws NullPointerException if null is passed in
658     * @since 3.0
659     */
660    public static Calendar toCalendar(final Date date) {
661        final Calendar c = Calendar.getInstance();
662        c.setTime(date);
663        return c;
664    }
665
666    //-----------------------------------------------------------------------
667    /**
668     * Converts a {@code Date} of a given {@code TimeZone} into a {@code Calendar}
669     * @param date the date to convert to a Calendar
670     * @param tz the time zone of the {@code date}
671     * @return the created Calendar
672     * @throws NullPointerException if {@code date} or {@code tz} is null
673     */
674    public static Calendar toCalendar(final Date date, final TimeZone tz) {
675        final Calendar c = Calendar.getInstance(tz);
676        c.setTime(date);
677        return c;
678    }
679
680    //-----------------------------------------------------------------------
681    /**
682     * <p>Rounds a date, leaving the field specified as the most
683     * significant field.</p>
684     *
685     * <p>For example, if you had the date-time of 28 Mar 2002
686     * 13:45:01.231, if this was passed with HOUR, it would return
687     * 28 Mar 2002 14:00:00.000. If this was passed with MONTH, it
688     * would return 1 April 2002 0:00:00.000.</p>
689     *
690     * <p>For a date in a timezone that handles the change to daylight
691     * saving time, rounding to Calendar.HOUR_OF_DAY will behave as follows.
692     * Suppose daylight saving time begins at 02:00 on March 30. Rounding a
693     * date that crosses this time would produce the following values:
694     * </p>
695     * <ul>
696     * <li>March 30, 2003 01:10 rounds to March 30, 2003 01:00</li>
697     * <li>March 30, 2003 01:40 rounds to March 30, 2003 03:00</li>
698     * <li>March 30, 2003 02:10 rounds to March 30, 2003 03:00</li>
699     * <li>March 30, 2003 02:40 rounds to March 30, 2003 04:00</li>
700     * </ul>
701     *
702     * @param date  the date to work with, not null
703     * @param field  the field from {@code Calendar} or {@code SEMI_MONTH}
704     * @return the different rounded date, not null
705     * @throws ArithmeticException if the year is over 280 million
706     */
707    public static Date round(final Date date, final int field) {
708        validateDateNotNull(date);
709        final Calendar gval = Calendar.getInstance();
710        gval.setTime(date);
711        modify(gval, field, ModifyType.ROUND);
712        return gval.getTime();
713    }
714
715    /**
716     * <p>Rounds a date, leaving the field specified as the most
717     * significant field.</p>
718     *
719     * <p>For example, if you had the date-time of 28 Mar 2002
720     * 13:45:01.231, if this was passed with HOUR, it would return
721     * 28 Mar 2002 14:00:00.000. If this was passed with MONTH, it
722     * would return 1 April 2002 0:00:00.000.</p>
723     *
724     * <p>For a date in a timezone that handles the change to daylight
725     * saving time, rounding to Calendar.HOUR_OF_DAY will behave as follows.
726     * Suppose daylight saving time begins at 02:00 on March 30. Rounding a
727     * date that crosses this time would produce the following values:
728     * </p>
729     * <ul>
730     * <li>March 30, 2003 01:10 rounds to March 30, 2003 01:00</li>
731     * <li>March 30, 2003 01:40 rounds to March 30, 2003 03:00</li>
732     * <li>March 30, 2003 02:10 rounds to March 30, 2003 03:00</li>
733     * <li>March 30, 2003 02:40 rounds to March 30, 2003 04:00</li>
734     * </ul>
735     *
736     * @param date  the date to work with, not null
737     * @param field  the field from {@code Calendar} or <code>SEMI_MONTH</code>
738     * @return the different rounded date, not null
739     * @throws IllegalArgumentException if the date is <code>null</code>
740     * @throws ArithmeticException if the year is over 280 million
741     */
742    public static Calendar round(final Calendar date, final int field) {
743        if (date == null) {
744            throw new IllegalArgumentException("The date must not be null");
745        }
746        final Calendar rounded = (Calendar) date.clone();
747        modify(rounded, field, ModifyType.ROUND);
748        return rounded;
749    }
750
751    /**
752     * <p>Rounds a date, leaving the field specified as the most
753     * significant field.</p>
754     *
755     * <p>For example, if you had the date-time of 28 Mar 2002
756     * 13:45:01.231, if this was passed with HOUR, it would return
757     * 28 Mar 2002 14:00:00.000. If this was passed with MONTH, it
758     * would return 1 April 2002 0:00:00.000.</p>
759     *
760     * <p>For a date in a timezone that handles the change to daylight
761     * saving time, rounding to Calendar.HOUR_OF_DAY will behave as follows.
762     * Suppose daylight saving time begins at 02:00 on March 30. Rounding a
763     * date that crosses this time would produce the following values:
764     * </p>
765     * <ul>
766     * <li>March 30, 2003 01:10 rounds to March 30, 2003 01:00</li>
767     * <li>March 30, 2003 01:40 rounds to March 30, 2003 03:00</li>
768     * <li>March 30, 2003 02:10 rounds to March 30, 2003 03:00</li>
769     * <li>March 30, 2003 02:40 rounds to March 30, 2003 04:00</li>
770     * </ul>
771     *
772     * @param date  the date to work with, either {@code Date} or {@code Calendar}, not null
773     * @param field  the field from {@code Calendar} or <code>SEMI_MONTH</code>
774     * @return the different rounded date, not null
775     * @throws IllegalArgumentException if the date is <code>null</code>
776     * @throws ClassCastException if the object type is not a {@code Date} or {@code Calendar}
777     * @throws ArithmeticException if the year is over 280 million
778     */
779    public static Date round(final Object date, final int field) {
780        if (date == null) {
781            throw new IllegalArgumentException("The date must not be null");
782        }
783        if (date instanceof Date) {
784            return round((Date) date, field);
785        } else if (date instanceof Calendar) {
786            return round((Calendar) date, field).getTime();
787        } else {
788            throw new ClassCastException("Could not round " + date);
789        }
790    }
791
792    //-----------------------------------------------------------------------
793    /**
794     * <p>Truncates a date, leaving the field specified as the most
795     * significant field.</p>
796     *
797     * <p>For example, if you had the date-time of 28 Mar 2002
798     * 13:45:01.231, if you passed with HOUR, it would return 28 Mar
799     * 2002 13:00:00.000.  If this was passed with MONTH, it would
800     * return 1 Mar 2002 0:00:00.000.</p>
801     *
802     * @param date  the date to work with, not null
803     * @param field  the field from {@code Calendar} or <code>SEMI_MONTH</code>
804     * @return the different truncated date, not null
805     * @throws IllegalArgumentException if the date is <code>null</code>
806     * @throws ArithmeticException if the year is over 280 million
807     */
808    public static Date truncate(final Date date, final int field) {
809        validateDateNotNull(date);
810        final Calendar gval = Calendar.getInstance();
811        gval.setTime(date);
812        modify(gval, field, ModifyType.TRUNCATE);
813        return gval.getTime();
814    }
815
816    /**
817     * <p>Truncates a date, leaving the field specified as the most
818     * significant field.</p>
819     *
820     * <p>For example, if you had the date-time of 28 Mar 2002
821     * 13:45:01.231, if you passed with HOUR, it would return 28 Mar
822     * 2002 13:00:00.000.  If this was passed with MONTH, it would
823     * return 1 Mar 2002 0:00:00.000.</p>
824     *
825     * @param date  the date to work with, not null
826     * @param field  the field from {@code Calendar} or <code>SEMI_MONTH</code>
827     * @return the different truncated date, not null
828     * @throws IllegalArgumentException if the date is <code>null</code>
829     * @throws ArithmeticException if the year is over 280 million
830     */
831    public static Calendar truncate(final Calendar date, final int field) {
832        if (date == null) {
833            throw new IllegalArgumentException("The date must not be null");
834        }
835        final Calendar truncated = (Calendar) date.clone();
836        modify(truncated, field, ModifyType.TRUNCATE);
837        return truncated;
838    }
839
840    /**
841     * <p>Truncates a date, leaving the field specified as the most
842     * significant field.</p>
843     *
844     * <p>For example, if you had the date-time of 28 Mar 2002
845     * 13:45:01.231, if you passed with HOUR, it would return 28 Mar
846     * 2002 13:00:00.000.  If this was passed with MONTH, it would
847     * return 1 Mar 2002 0:00:00.000.</p>
848     *
849     * @param date  the date to work with, either {@code Date} or {@code Calendar}, not null
850     * @param field  the field from {@code Calendar} or <code>SEMI_MONTH</code>
851     * @return the different truncated date, not null
852     * @throws IllegalArgumentException if the date is <code>null</code>
853     * @throws ClassCastException if the object type is not a {@code Date} or {@code Calendar}
854     * @throws ArithmeticException if the year is over 280 million
855     */
856    public static Date truncate(final Object date, final int field) {
857        if (date == null) {
858            throw new IllegalArgumentException("The date must not be null");
859        }
860        if (date instanceof Date) {
861            return truncate((Date) date, field);
862        } else if (date instanceof Calendar) {
863            return truncate((Calendar) date, field).getTime();
864        } else {
865            throw new ClassCastException("Could not truncate " + date);
866        }
867    }
868
869  //-----------------------------------------------------------------------
870    /**
871     * <p>Gets a date ceiling, leaving the field specified as the most
872     * significant field.</p>
873     *
874     * <p>For example, if you had the date-time of 28 Mar 2002
875     * 13:45:01.231, if you passed with HOUR, it would return 28 Mar
876     * 2002 14:00:00.000.  If this was passed with MONTH, it would
877     * return 1 Apr 2002 0:00:00.000.</p>
878     *
879     * @param date  the date to work with, not null
880     * @param field  the field from {@code Calendar} or <code>SEMI_MONTH</code>
881     * @return the different ceil date, not null
882     * @throws IllegalArgumentException if the date is <code>null</code>
883     * @throws ArithmeticException if the year is over 280 million
884     * @since 2.5
885     */
886    public static Date ceiling(final Date date, final int field) {
887        validateDateNotNull(date);
888        final Calendar gval = Calendar.getInstance();
889        gval.setTime(date);
890        modify(gval, field, ModifyType.CEILING);
891        return gval.getTime();
892    }
893
894    /**
895     * <p>Gets a date ceiling, leaving the field specified as the most
896     * significant field.</p>
897     *
898     * <p>For example, if you had the date-time of 28 Mar 2002
899     * 13:45:01.231, if you passed with HOUR, it would return 28 Mar
900     * 2002 14:00:00.000.  If this was passed with MONTH, it would
901     * return 1 Apr 2002 0:00:00.000.</p>
902     *
903     * @param date  the date to work with, not null
904     * @param field  the field from {@code Calendar} or <code>SEMI_MONTH</code>
905     * @return the different ceil date, not null
906     * @throws IllegalArgumentException if the date is <code>null</code>
907     * @throws ArithmeticException if the year is over 280 million
908     * @since 2.5
909     */
910    public static Calendar ceiling(final Calendar date, final int field) {
911        if (date == null) {
912            throw new IllegalArgumentException("The date must not be null");
913        }
914        final Calendar ceiled = (Calendar) date.clone();
915        modify(ceiled, field, ModifyType.CEILING);
916        return ceiled;
917    }
918
919    /**
920     * <p>Gets a date ceiling, leaving the field specified as the most
921     * significant field.</p>
922     *
923     * <p>For example, if you had the date-time of 28 Mar 2002
924     * 13:45:01.231, if you passed with HOUR, it would return 28 Mar
925     * 2002 14:00:00.000.  If this was passed with MONTH, it would
926     * return 1 Apr 2002 0:00:00.000.</p>
927     *
928     * @param date  the date to work with, either {@code Date} or {@code Calendar}, not null
929     * @param field  the field from {@code Calendar} or <code>SEMI_MONTH</code>
930     * @return the different ceil date, not null
931     * @throws IllegalArgumentException if the date is <code>null</code>
932     * @throws ClassCastException if the object type is not a {@code Date} or {@code Calendar}
933     * @throws ArithmeticException if the year is over 280 million
934     * @since 2.5
935     */
936    public static Date ceiling(final Object date, final int field) {
937        if (date == null) {
938            throw new IllegalArgumentException("The date must not be null");
939        }
940        if (date instanceof Date) {
941            return ceiling((Date) date, field);
942        } else if (date instanceof Calendar) {
943            return ceiling((Calendar) date, field).getTime();
944        } else {
945            throw new ClassCastException("Could not find ceiling of for type: " + date.getClass());
946        }
947    }
948
949    //-----------------------------------------------------------------------
950    /**
951     * <p>Internal calculation method.</p>
952     *
953     * @param val  the calendar, not null
954     * @param field  the field constant
955     * @param modType  type to truncate, round or ceiling
956     * @throws ArithmeticException if the year is over 280 million
957     */
958    private static void modify(final Calendar val, final int field, final ModifyType modType) {
959        if (val.get(Calendar.YEAR) > 280000000) {
960            throw new ArithmeticException("Calendar value too large for accurate calculations");
961        }
962
963        if (field == Calendar.MILLISECOND) {
964            return;
965        }
966
967        // ----------------- Fix for LANG-59 ---------------------- START ---------------
968        // see http://issues.apache.org/jira/browse/LANG-59
969        //
970        // Manually truncate milliseconds, seconds and minutes, rather than using
971        // Calendar methods.
972
973        final Date date = val.getTime();
974        long time = date.getTime();
975        boolean done = false;
976
977        // truncate milliseconds
978        final int millisecs = val.get(Calendar.MILLISECOND);
979        if (ModifyType.TRUNCATE == modType || millisecs < 500) {
980            time = time - millisecs;
981        }
982        if (field == Calendar.SECOND) {
983            done = true;
984        }
985
986        // truncate seconds
987        final int seconds = val.get(Calendar.SECOND);
988        if (!done && (ModifyType.TRUNCATE == modType || seconds < 30)) {
989            time = time - (seconds * 1000L);
990        }
991        if (field == Calendar.MINUTE) {
992            done = true;
993        }
994
995        // truncate minutes
996        final int minutes = val.get(Calendar.MINUTE);
997        if (!done && (ModifyType.TRUNCATE == modType || minutes < 30)) {
998            time = time - (minutes * 60000L);
999        }
1000
1001        // reset time
1002        if (date.getTime() != time) {
1003            date.setTime(time);
1004            val.setTime(date);
1005        }
1006        // ----------------- Fix for LANG-59 ----------------------- END ----------------
1007
1008        boolean roundUp = false;
1009        for (final int[] aField : fields) {
1010            for (final int element : aField) {
1011                if (element == field) {
1012                    //This is our field... we stop looping
1013                    if (modType == ModifyType.CEILING || modType == ModifyType.ROUND && roundUp) {
1014                        if (field == DateUtils.SEMI_MONTH) {
1015                            //This is a special case that's hard to generalize
1016                            //If the date is 1, we round up to 16, otherwise
1017                            //  we subtract 15 days and add 1 month
1018                            if (val.get(Calendar.DATE) == 1) {
1019                                val.add(Calendar.DATE, 15);
1020                            } else {
1021                                val.add(Calendar.DATE, -15);
1022                                val.add(Calendar.MONTH, 1);
1023                            }
1024// ----------------- Fix for LANG-440 ---------------------- START ---------------
1025                        } else if (field == Calendar.AM_PM) {
1026                            // This is a special case
1027                            // If the time is 0, we round up to 12, otherwise
1028                            //  we subtract 12 hours and add 1 day
1029                            if (val.get(Calendar.HOUR_OF_DAY) == 0) {
1030                                val.add(Calendar.HOUR_OF_DAY, 12);
1031                            } else {
1032                                val.add(Calendar.HOUR_OF_DAY, -12);
1033                                val.add(Calendar.DATE, 1);
1034                            }
1035// ----------------- Fix for LANG-440 ---------------------- END ---------------
1036                        } else {
1037                            //We need at add one to this field since the
1038                            //  last number causes us to round up
1039                            val.add(aField[0], 1);
1040                        }
1041                    }
1042                    return;
1043                }
1044            }
1045            //We have various fields that are not easy roundings
1046            int offset = 0;
1047            boolean offsetSet = false;
1048            //These are special types of fields that require different rounding rules
1049            switch (field) {
1050                case DateUtils.SEMI_MONTH:
1051                    if (aField[0] == Calendar.DATE) {
1052                        //If we're going to drop the DATE field's value,
1053                        //  we want to do this our own way.
1054                        //We need to subtrace 1 since the date has a minimum of 1
1055                        offset = val.get(Calendar.DATE) - 1;
1056                        //If we're above 15 days adjustment, that means we're in the
1057                        //  bottom half of the month and should stay accordingly.
1058                        if (offset >= 15) {
1059                            offset -= 15;
1060                        }
1061                        //Record whether we're in the top or bottom half of that range
1062                        roundUp = offset > 7;
1063                        offsetSet = true;
1064                    }
1065                    break;
1066                case Calendar.AM_PM:
1067                    if (aField[0] == Calendar.HOUR_OF_DAY) {
1068                        //If we're going to drop the HOUR field's value,
1069                        //  we want to do this our own way.
1070                        offset = val.get(Calendar.HOUR_OF_DAY);
1071                        if (offset >= 12) {
1072                            offset -= 12;
1073                        }
1074                        roundUp = offset >= 6;
1075                        offsetSet = true;
1076                    }
1077                    break;
1078                default:
1079                    break;
1080            }
1081            if (!offsetSet) {
1082                final int min = val.getActualMinimum(aField[0]);
1083                final int max = val.getActualMaximum(aField[0]);
1084                //Calculate the offset from the minimum allowed value
1085                offset = val.get(aField[0]) - min;
1086                //Set roundUp if this is more than half way between the minimum and maximum
1087                roundUp = offset > ((max - min) / 2);
1088            }
1089            //We need to remove this field
1090            if (offset != 0) {
1091                val.set(aField[0], val.get(aField[0]) - offset);
1092            }
1093        }
1094        throw new IllegalArgumentException("The field " + field + " is not supported");
1095
1096    }
1097
1098    //-----------------------------------------------------------------------
1099    /**
1100     * <p>Constructs an <code>Iterator</code> over each day in a date
1101     * range defined by a focus date and range style.</p>
1102     *
1103     * <p>For instance, passing Thursday, July 4, 2002 and a
1104     * <code>RANGE_MONTH_SUNDAY</code> will return an <code>Iterator</code>
1105     * that starts with Sunday, June 30, 2002 and ends with Saturday, August 3,
1106     * 2002, returning a Calendar instance for each intermediate day.</p>
1107     *
1108     * <p>This method provides an iterator that returns Calendar objects.
1109     * The days are progressed using {@link Calendar#add(int, int)}.</p>
1110     *
1111     * @param focus  the date to work with, not null
1112     * @param rangeStyle  the style constant to use. Must be one of
1113     * {@link DateUtils#RANGE_MONTH_SUNDAY},
1114     * {@link DateUtils#RANGE_MONTH_MONDAY},
1115     * {@link DateUtils#RANGE_WEEK_SUNDAY},
1116     * {@link DateUtils#RANGE_WEEK_MONDAY},
1117     * {@link DateUtils#RANGE_WEEK_RELATIVE},
1118     * {@link DateUtils#RANGE_WEEK_CENTER}
1119     * @return the date iterator, not null, not null
1120     * @throws IllegalArgumentException if the date is <code>null</code>
1121     * @throws IllegalArgumentException if the rangeStyle is invalid
1122     */
1123    public static Iterator<Calendar> iterator(final Date focus, final int rangeStyle) {
1124        validateDateNotNull(focus);
1125        final Calendar gval = Calendar.getInstance();
1126        gval.setTime(focus);
1127        return iterator(gval, rangeStyle);
1128    }
1129
1130    /**
1131     * <p>Constructs an <code>Iterator</code> over each day in a date
1132     * range defined by a focus date and range style.</p>
1133     *
1134     * <p>For instance, passing Thursday, July 4, 2002 and a
1135     * <code>RANGE_MONTH_SUNDAY</code> will return an <code>Iterator</code>
1136     * that starts with Sunday, June 30, 2002 and ends with Saturday, August 3,
1137     * 2002, returning a Calendar instance for each intermediate day.</p>
1138     *
1139     * <p>This method provides an iterator that returns Calendar objects.
1140     * The days are progressed using {@link Calendar#add(int, int)}.</p>
1141     *
1142     * @param focus  the date to work with, not null
1143     * @param rangeStyle  the style constant to use. Must be one of
1144     * {@link DateUtils#RANGE_MONTH_SUNDAY},
1145     * {@link DateUtils#RANGE_MONTH_MONDAY},
1146     * {@link DateUtils#RANGE_WEEK_SUNDAY},
1147     * {@link DateUtils#RANGE_WEEK_MONDAY},
1148     * {@link DateUtils#RANGE_WEEK_RELATIVE},
1149     * {@link DateUtils#RANGE_WEEK_CENTER}
1150     * @return the date iterator, not null
1151     * @throws IllegalArgumentException if the date is <code>null</code>
1152     * @throws IllegalArgumentException if the rangeStyle is invalid
1153     */
1154    public static Iterator<Calendar> iterator(final Calendar focus, final int rangeStyle) {
1155        if (focus == null) {
1156            throw new IllegalArgumentException("The date must not be null");
1157        }
1158        Calendar start = null;
1159        Calendar end = null;
1160        int startCutoff = Calendar.SUNDAY;
1161        int endCutoff = Calendar.SATURDAY;
1162        switch (rangeStyle) {
1163            case RANGE_MONTH_SUNDAY:
1164            case RANGE_MONTH_MONDAY:
1165                //Set start to the first of the month
1166                start = truncate(focus, Calendar.MONTH);
1167                //Set end to the last of the month
1168                end = (Calendar) start.clone();
1169                end.add(Calendar.MONTH, 1);
1170                end.add(Calendar.DATE, -1);
1171                //Loop start back to the previous sunday or monday
1172                if (rangeStyle == RANGE_MONTH_MONDAY) {
1173                    startCutoff = Calendar.MONDAY;
1174                    endCutoff = Calendar.SUNDAY;
1175                }
1176                break;
1177            case RANGE_WEEK_SUNDAY:
1178            case RANGE_WEEK_MONDAY:
1179            case RANGE_WEEK_RELATIVE:
1180            case RANGE_WEEK_CENTER:
1181                //Set start and end to the current date
1182                start = truncate(focus, Calendar.DATE);
1183                end = truncate(focus, Calendar.DATE);
1184                switch (rangeStyle) {
1185                    case RANGE_WEEK_SUNDAY:
1186                        //already set by default
1187                        break;
1188                    case RANGE_WEEK_MONDAY:
1189                        startCutoff = Calendar.MONDAY;
1190                        endCutoff = Calendar.SUNDAY;
1191                        break;
1192                    case RANGE_WEEK_RELATIVE:
1193                        startCutoff = focus.get(Calendar.DAY_OF_WEEK);
1194                        endCutoff = startCutoff - 1;
1195                        break;
1196                    case RANGE_WEEK_CENTER:
1197                        startCutoff = focus.get(Calendar.DAY_OF_WEEK) - 3;
1198                        endCutoff = focus.get(Calendar.DAY_OF_WEEK) + 3;
1199                        break;
1200                    default:
1201                        break;
1202                }
1203                break;
1204            default:
1205                throw new IllegalArgumentException("The range style " + rangeStyle + " is not valid.");
1206        }
1207        if (startCutoff < Calendar.SUNDAY) {
1208            startCutoff += 7;
1209        }
1210        if (startCutoff > Calendar.SATURDAY) {
1211            startCutoff -= 7;
1212        }
1213        if (endCutoff < Calendar.SUNDAY) {
1214            endCutoff += 7;
1215        }
1216        if (endCutoff > Calendar.SATURDAY) {
1217            endCutoff -= 7;
1218        }
1219        while (start.get(Calendar.DAY_OF_WEEK) != startCutoff) {
1220            start.add(Calendar.DATE, -1);
1221        }
1222        while (end.get(Calendar.DAY_OF_WEEK) != endCutoff) {
1223            end.add(Calendar.DATE, 1);
1224        }
1225        return new DateIterator(start, end);
1226    }
1227
1228    /**
1229     * <p>Constructs an <code>Iterator</code> over each day in a date
1230     * range defined by a focus date and range style.</p>
1231     *
1232     * <p>For instance, passing Thursday, July 4, 2002 and a
1233     * <code>RANGE_MONTH_SUNDAY</code> will return an <code>Iterator</code>
1234     * that starts with Sunday, June 30, 2002 and ends with Saturday, August 3,
1235     * 2002, returning a Calendar instance for each intermediate day.</p>
1236     *
1237     * @param focus  the date to work with, either {@code Date} or {@code Calendar}, not null
1238     * @param rangeStyle  the style constant to use. Must be one of the range
1239     * styles listed for the {@link #iterator(Calendar, int)} method.
1240     * @return the date iterator, not null
1241     * @throws IllegalArgumentException if the date is <code>null</code>
1242     * @throws ClassCastException if the object type is not a {@code Date} or {@code Calendar}
1243     */
1244    public static Iterator<?> iterator(final Object focus, final int rangeStyle) {
1245        if (focus == null) {
1246            throw new IllegalArgumentException("The date must not be null");
1247        }
1248        if (focus instanceof Date) {
1249            return iterator((Date) focus, rangeStyle);
1250        } else if (focus instanceof Calendar) {
1251            return iterator((Calendar) focus, rangeStyle);
1252        } else {
1253            throw new ClassCastException("Could not iterate based on " + focus);
1254        }
1255    }
1256
1257    /**
1258     * <p>Returns the number of milliseconds within the
1259     * fragment. All datefields greater than the fragment will be ignored.</p>
1260     *
1261     * <p>Asking the milliseconds of any date will only return the number of milliseconds
1262     * of the current second (resulting in a number between 0 and 999). This
1263     * method will retrieve the number of milliseconds for any fragment.
1264     * For example, if you want to calculate the number of milliseconds past today,
1265     * your fragment is Calendar.DATE or Calendar.DAY_OF_YEAR. The result will
1266     * be all milliseconds of the past hour(s), minutes(s) and second(s).</p>
1267     *
1268     * <p>Valid fragments are: Calendar.YEAR, Calendar.MONTH, both
1269     * Calendar.DAY_OF_YEAR and Calendar.DATE, Calendar.HOUR_OF_DAY,
1270     * Calendar.MINUTE, Calendar.SECOND and Calendar.MILLISECOND
1271     * A fragment less than or equal to a SECOND field will return 0.</p>
1272     *
1273     * <ul>
1274     *  <li>January 1, 2008 7:15:10.538 with Calendar.SECOND as fragment will return 538</li>
1275     *  <li>January 6, 2008 7:15:10.538 with Calendar.SECOND as fragment will return 538</li>
1276     *  <li>January 6, 2008 7:15:10.538 with Calendar.MINUTE as fragment will return 10538 (10*1000 + 538)</li>
1277     *  <li>January 16, 2008 7:15:10.538 with Calendar.MILLISECOND as fragment will return 0
1278     *   (a millisecond cannot be split in milliseconds)</li>
1279     * </ul>
1280     *
1281     * @param date the date to work with, not null
1282     * @param fragment the {@code Calendar} field part of date to calculate
1283     * @return number of milliseconds within the fragment of date
1284     * @throws IllegalArgumentException if the date is <code>null</code> or
1285     * fragment is not supported
1286     * @since 2.4
1287     */
1288    public static long getFragmentInMilliseconds(final Date date, final int fragment) {
1289        return getFragment(date, fragment, TimeUnit.MILLISECONDS);
1290    }
1291
1292    /**
1293     * <p>Returns the number of seconds within the
1294     * fragment. All datefields greater than the fragment will be ignored.</p>
1295     *
1296     * <p>Asking the seconds of any date will only return the number of seconds
1297     * of the current minute (resulting in a number between 0 and 59). This
1298     * method will retrieve the number of seconds for any fragment.
1299     * For example, if you want to calculate the number of seconds past today,
1300     * your fragment is Calendar.DATE or Calendar.DAY_OF_YEAR. The result will
1301     * be all seconds of the past hour(s) and minutes(s).</p>
1302     *
1303     * <p>Valid fragments are: Calendar.YEAR, Calendar.MONTH, both
1304     * Calendar.DAY_OF_YEAR and Calendar.DATE, Calendar.HOUR_OF_DAY,
1305     * Calendar.MINUTE, Calendar.SECOND and Calendar.MILLISECOND
1306     * A fragment less than or equal to a SECOND field will return 0.</p>
1307     *
1308     * <ul>
1309     *  <li>January 1, 2008 7:15:10.538 with Calendar.MINUTE as fragment will return 10
1310     *   (equivalent to deprecated date.getSeconds())</li>
1311     *  <li>January 6, 2008 7:15:10.538 with Calendar.MINUTE as fragment will return 10
1312     *   (equivalent to deprecated date.getSeconds())</li>
1313     *  <li>January 6, 2008 7:15:10.538 with Calendar.DAY_OF_YEAR as fragment will return 26110
1314     *   (7*3600 + 15*60 + 10)</li>
1315     *  <li>January 16, 2008 7:15:10.538 with Calendar.MILLISECOND as fragment will return 0
1316     *   (a millisecond cannot be split in seconds)</li>
1317     * </ul>
1318     *
1319     * @param date the date to work with, not null
1320     * @param fragment the {@code Calendar} field part of date to calculate
1321     * @return number of seconds within the fragment of date
1322     * @throws IllegalArgumentException if the date is <code>null</code> or
1323     * fragment is not supported
1324     * @since 2.4
1325     */
1326    public static long getFragmentInSeconds(final Date date, final int fragment) {
1327        return getFragment(date, fragment, TimeUnit.SECONDS);
1328    }
1329
1330    /**
1331     * <p>Returns the number of minutes within the
1332     * fragment. All datefields greater than the fragment will be ignored.</p>
1333     *
1334     * <p>Asking the minutes of any date will only return the number of minutes
1335     * of the current hour (resulting in a number between 0 and 59). This
1336     * method will retrieve the number of minutes for any fragment.
1337     * For example, if you want to calculate the number of minutes past this month,
1338     * your fragment is Calendar.MONTH. The result will be all minutes of the
1339     * past day(s) and hour(s).</p>
1340     *
1341     * <p>Valid fragments are: Calendar.YEAR, Calendar.MONTH, both
1342     * Calendar.DAY_OF_YEAR and Calendar.DATE, Calendar.HOUR_OF_DAY,
1343     * Calendar.MINUTE, Calendar.SECOND and Calendar.MILLISECOND
1344     * A fragment less than or equal to a MINUTE field will return 0.</p>
1345     *
1346     * <ul>
1347     *  <li>January 1, 2008 7:15:10.538 with Calendar.HOUR_OF_DAY as fragment will return 15
1348     *   (equivalent to deprecated date.getMinutes())</li>
1349     *  <li>January 6, 2008 7:15:10.538 with Calendar.HOUR_OF_DAY as fragment will return 15
1350     *   (equivalent to deprecated date.getMinutes())</li>
1351     *  <li>January 1, 2008 7:15:10.538 with Calendar.MONTH as fragment will return 15</li>
1352     *  <li>January 6, 2008 7:15:10.538 with Calendar.MONTH as fragment will return 435 (7*60 + 15)</li>
1353     *  <li>January 16, 2008 7:15:10.538 with Calendar.MILLISECOND as fragment will return 0
1354     *   (a millisecond cannot be split in minutes)</li>
1355     * </ul>
1356     *
1357     * @param date the date to work with, not null
1358     * @param fragment the {@code Calendar} field part of date to calculate
1359     * @return number of minutes within the fragment of date
1360     * @throws IllegalArgumentException if the date is <code>null</code> or
1361     * fragment is not supported
1362     * @since 2.4
1363     */
1364    public static long getFragmentInMinutes(final Date date, final int fragment) {
1365        return getFragment(date, fragment, TimeUnit.MINUTES);
1366    }
1367
1368    /**
1369     * <p>Returns the number of hours within the
1370     * fragment. All datefields greater than the fragment will be ignored.</p>
1371     *
1372     * <p>Asking the hours of any date will only return the number of hours
1373     * of the current day (resulting in a number between 0 and 23). This
1374     * method will retrieve the number of hours for any fragment.
1375     * For example, if you want to calculate the number of hours past this month,
1376     * your fragment is Calendar.MONTH. The result will be all hours of the
1377     * past day(s).</p>
1378     *
1379     * <p>Valid fragments are: Calendar.YEAR, Calendar.MONTH, both
1380     * Calendar.DAY_OF_YEAR and Calendar.DATE, Calendar.HOUR_OF_DAY,
1381     * Calendar.MINUTE, Calendar.SECOND and Calendar.MILLISECOND
1382     * A fragment less than or equal to a HOUR field will return 0.</p>
1383     *
1384     * <ul>
1385     *  <li>January 1, 2008 7:15:10.538 with Calendar.DAY_OF_YEAR as fragment will return 7
1386     *   (equivalent to deprecated date.getHours())</li>
1387     *  <li>January 6, 2008 7:15:10.538 with Calendar.DAY_OF_YEAR as fragment will return 7
1388     *   (equivalent to deprecated date.getHours())</li>
1389     *  <li>January 1, 2008 7:15:10.538 with Calendar.MONTH as fragment will return 7</li>
1390     *  <li>January 6, 2008 7:15:10.538 with Calendar.MONTH as fragment will return 127 (5*24 + 7)</li>
1391     *  <li>January 16, 2008 7:15:10.538 with Calendar.MILLISECOND as fragment will return 0
1392     *   (a millisecond cannot be split in hours)</li>
1393     * </ul>
1394     *
1395     * @param date the date to work with, not null
1396     * @param fragment the {@code Calendar} field part of date to calculate
1397     * @return number of hours within the fragment of date
1398     * @throws IllegalArgumentException if the date is <code>null</code> or
1399     * fragment is not supported
1400     * @since 2.4
1401     */
1402    public static long getFragmentInHours(final Date date, final int fragment) {
1403        return getFragment(date, fragment, TimeUnit.HOURS);
1404    }
1405
1406    /**
1407     * <p>Returns the number of days within the
1408     * fragment. All datefields greater than the fragment will be ignored.</p>
1409     *
1410     * <p>Asking the days of any date will only return the number of days
1411     * of the current month (resulting in a number between 1 and 31). This
1412     * method will retrieve the number of days for any fragment.
1413     * For example, if you want to calculate the number of days past this year,
1414     * your fragment is Calendar.YEAR. The result will be all days of the
1415     * past month(s).</p>
1416     *
1417     * <p>Valid fragments are: Calendar.YEAR, Calendar.MONTH, both
1418     * Calendar.DAY_OF_YEAR and Calendar.DATE, Calendar.HOUR_OF_DAY,
1419     * Calendar.MINUTE, Calendar.SECOND and Calendar.MILLISECOND
1420     * A fragment less than or equal to a DAY field will return 0.</p>
1421     *
1422     * <ul>
1423     *  <li>January 28, 2008 with Calendar.MONTH as fragment will return 28
1424     *   (equivalent to deprecated date.getDay())</li>
1425     *  <li>February 28, 2008 with Calendar.MONTH as fragment will return 28
1426     *   (equivalent to deprecated date.getDay())</li>
1427     *  <li>January 28, 2008 with Calendar.YEAR as fragment will return 28</li>
1428     *  <li>February 28, 2008 with Calendar.YEAR as fragment will return 59</li>
1429     *  <li>January 28, 2008 with Calendar.MILLISECOND as fragment will return 0
1430     *   (a millisecond cannot be split in days)</li>
1431     * </ul>
1432     *
1433     * @param date the date to work with, not null
1434     * @param fragment the {@code Calendar} field part of date to calculate
1435     * @return number of days  within the fragment of date
1436     * @throws IllegalArgumentException if the date is <code>null</code> or
1437     * fragment is not supported
1438     * @since 2.4
1439     */
1440    public static long getFragmentInDays(final Date date, final int fragment) {
1441        return getFragment(date, fragment, TimeUnit.DAYS);
1442    }
1443
1444    /**
1445     * <p>Returns the number of milliseconds within the
1446     * fragment. All datefields greater than the fragment will be ignored.</p>
1447     *
1448     * <p>Asking the milliseconds of any date will only return the number of milliseconds
1449     * of the current second (resulting in a number between 0 and 999). This
1450     * method will retrieve the number of milliseconds for any fragment.
1451     * For example, if you want to calculate the number of seconds past today,
1452     * your fragment is Calendar.DATE or Calendar.DAY_OF_YEAR. The result will
1453     * be all seconds of the past hour(s), minutes(s) and second(s).</p>
1454     *
1455     * <p>Valid fragments are: Calendar.YEAR, Calendar.MONTH, both
1456     * Calendar.DAY_OF_YEAR and Calendar.DATE, Calendar.HOUR_OF_DAY,
1457     * Calendar.MINUTE, Calendar.SECOND and Calendar.MILLISECOND
1458     * A fragment less than or equal to a MILLISECOND field will return 0.</p>
1459     *
1460     * <ul>
1461     *  <li>January 1, 2008 7:15:10.538 with Calendar.SECOND as fragment will return 538
1462     *   (equivalent to calendar.get(Calendar.MILLISECOND))</li>
1463     *  <li>January 6, 2008 7:15:10.538 with Calendar.SECOND as fragment will return 538
1464     *   (equivalent to calendar.get(Calendar.MILLISECOND))</li>
1465     *  <li>January 6, 2008 7:15:10.538 with Calendar.MINUTE as fragment will return 10538
1466     *   (10*1000 + 538)</li>
1467     *  <li>January 16, 2008 7:15:10.538 with Calendar.MILLISECOND as fragment will return 0
1468     *   (a millisecond cannot be split in milliseconds)</li>
1469     * </ul>
1470     *
1471     * @param calendar the calendar to work with, not null
1472     * @param fragment the {@code Calendar} field part of calendar to calculate
1473     * @return number of milliseconds within the fragment of date
1474     * @throws IllegalArgumentException if the date is <code>null</code> or
1475     * fragment is not supported
1476     * @since 2.4
1477     */
1478  public static long getFragmentInMilliseconds(final Calendar calendar, final int fragment) {
1479    return getFragment(calendar, fragment, TimeUnit.MILLISECONDS);
1480  }
1481    /**
1482     * <p>Returns the number of seconds within the
1483     * fragment. All datefields greater than the fragment will be ignored.</p>
1484     *
1485     * <p>Asking the seconds of any date will only return the number of seconds
1486     * of the current minute (resulting in a number between 0 and 59). This
1487     * method will retrieve the number of seconds for any fragment.
1488     * For example, if you want to calculate the number of seconds past today,
1489     * your fragment is Calendar.DATE or Calendar.DAY_OF_YEAR. The result will
1490     * be all seconds of the past hour(s) and minutes(s).</p>
1491     *
1492     * <p>Valid fragments are: Calendar.YEAR, Calendar.MONTH, both
1493     * Calendar.DAY_OF_YEAR and Calendar.DATE, Calendar.HOUR_OF_DAY,
1494     * Calendar.MINUTE, Calendar.SECOND and Calendar.MILLISECOND
1495     * A fragment less than or equal to a SECOND field will return 0.</p>
1496     *
1497     * <ul>
1498     *  <li>January 1, 2008 7:15:10.538 with Calendar.MINUTE as fragment will return 10
1499     *   (equivalent to calendar.get(Calendar.SECOND))</li>
1500     *  <li>January 6, 2008 7:15:10.538 with Calendar.MINUTE as fragment will return 10
1501     *   (equivalent to calendar.get(Calendar.SECOND))</li>
1502     *  <li>January 6, 2008 7:15:10.538 with Calendar.DAY_OF_YEAR as fragment will return 26110
1503     *   (7*3600 + 15*60 + 10)</li>
1504     *  <li>January 16, 2008 7:15:10.538 with Calendar.MILLISECOND as fragment will return 0
1505     *   (a millisecond cannot be split in seconds)</li>
1506     * </ul>
1507     *
1508     * @param calendar the calendar to work with, not null
1509     * @param fragment the {@code Calendar} field part of calendar to calculate
1510     * @return number of seconds within the fragment of date
1511     * @throws IllegalArgumentException if the date is <code>null</code> or
1512     * fragment is not supported
1513     * @since 2.4
1514     */
1515    public static long getFragmentInSeconds(final Calendar calendar, final int fragment) {
1516        return getFragment(calendar, fragment, TimeUnit.SECONDS);
1517    }
1518
1519    /**
1520     * <p>Returns the number of minutes within the
1521     * fragment. All datefields greater than the fragment will be ignored.</p>
1522     *
1523     * <p>Asking the minutes of any date will only return the number of minutes
1524     * of the current hour (resulting in a number between 0 and 59). This
1525     * method will retrieve the number of minutes for any fragment.
1526     * For example, if you want to calculate the number of minutes past this month,
1527     * your fragment is Calendar.MONTH. The result will be all minutes of the
1528     * past day(s) and hour(s).</p>
1529     *
1530     * <p>Valid fragments are: Calendar.YEAR, Calendar.MONTH, both
1531     * Calendar.DAY_OF_YEAR and Calendar.DATE, Calendar.HOUR_OF_DAY,
1532     * Calendar.MINUTE, Calendar.SECOND and Calendar.MILLISECOND
1533     * A fragment less than or equal to a MINUTE field will return 0.</p>
1534     *
1535     * <ul>
1536     *  <li>January 1, 2008 7:15:10.538 with Calendar.HOUR_OF_DAY as fragment will return 15
1537     *   (equivalent to calendar.get(Calendar.MINUTES))</li>
1538     *  <li>January 6, 2008 7:15:10.538 with Calendar.HOUR_OF_DAY as fragment will return 15
1539     *   (equivalent to calendar.get(Calendar.MINUTES))</li>
1540     *  <li>January 1, 2008 7:15:10.538 with Calendar.MONTH as fragment will return 15</li>
1541     *  <li>January 6, 2008 7:15:10.538 with Calendar.MONTH as fragment will return 435 (7*60 + 15)</li>
1542     *  <li>January 16, 2008 7:15:10.538 with Calendar.MILLISECOND as fragment will return 0
1543     *   (a millisecond cannot be split in minutes)</li>
1544     * </ul>
1545     *
1546     * @param calendar the calendar to work with, not null
1547     * @param fragment the {@code Calendar} field part of calendar to calculate
1548     * @return number of minutes within the fragment of date
1549     * @throws IllegalArgumentException if the date is <code>null</code> or
1550     * fragment is not supported
1551     * @since 2.4
1552     */
1553    public static long getFragmentInMinutes(final Calendar calendar, final int fragment) {
1554        return getFragment(calendar, fragment, TimeUnit.MINUTES);
1555    }
1556
1557    /**
1558     * <p>Returns the number of hours within the
1559     * fragment. All datefields greater than the fragment will be ignored.</p>
1560     *
1561     * <p>Asking the hours of any date will only return the number of hours
1562     * of the current day (resulting in a number between 0 and 23). This
1563     * method will retrieve the number of hours for any fragment.
1564     * For example, if you want to calculate the number of hours past this month,
1565     * your fragment is Calendar.MONTH. The result will be all hours of the
1566     * past day(s).</p>
1567     *
1568     * <p>Valid fragments are: Calendar.YEAR, Calendar.MONTH, both
1569     * Calendar.DAY_OF_YEAR and Calendar.DATE, Calendar.HOUR_OF_DAY,
1570     * Calendar.MINUTE, Calendar.SECOND and Calendar.MILLISECOND
1571     * A fragment less than or equal to a HOUR field will return 0.</p>
1572     *
1573     * <ul>
1574     *  <li>January 1, 2008 7:15:10.538 with Calendar.DAY_OF_YEAR as fragment will return 7
1575     *   (equivalent to calendar.get(Calendar.HOUR_OF_DAY))</li>
1576     *  <li>January 6, 2008 7:15:10.538 with Calendar.DAY_OF_YEAR as fragment will return 7
1577     *   (equivalent to calendar.get(Calendar.HOUR_OF_DAY))</li>
1578     *  <li>January 1, 2008 7:15:10.538 with Calendar.MONTH as fragment will return 7</li>
1579     *  <li>January 6, 2008 7:15:10.538 with Calendar.MONTH as fragment will return 127 (5*24 + 7)</li>
1580     *  <li>January 16, 2008 7:15:10.538 with Calendar.MILLISECOND as fragment will return 0
1581     *   (a millisecond cannot be split in hours)</li>
1582     * </ul>
1583     *
1584     * @param calendar the calendar to work with, not null
1585     * @param fragment the {@code Calendar} field part of calendar to calculate
1586     * @return number of hours within the fragment of date
1587     * @throws IllegalArgumentException if the date is <code>null</code> or
1588     * fragment is not supported
1589     * @since 2.4
1590     */
1591    public static long getFragmentInHours(final Calendar calendar, final int fragment) {
1592        return getFragment(calendar, fragment, TimeUnit.HOURS);
1593    }
1594
1595    /**
1596     * <p>Returns the number of days within the
1597     * fragment. All datefields greater than the fragment will be ignored.</p>
1598     *
1599     * <p>Asking the days of any date will only return the number of days
1600     * of the current month (resulting in a number between 1 and 31). This
1601     * method will retrieve the number of days for any fragment.
1602     * For example, if you want to calculate the number of days past this year,
1603     * your fragment is Calendar.YEAR. The result will be all days of the
1604     * past month(s).</p>
1605     *
1606     * <p>Valid fragments are: Calendar.YEAR, Calendar.MONTH, both
1607     * Calendar.DAY_OF_YEAR and Calendar.DATE, Calendar.HOUR_OF_DAY,
1608     * Calendar.MINUTE, Calendar.SECOND and Calendar.MILLISECOND
1609     * A fragment less than or equal to a DAY field will return 0.</p>
1610     *
1611     * <ul>
1612     *  <li>January 28, 2008 with Calendar.MONTH as fragment will return 28
1613     *   (equivalent to calendar.get(Calendar.DAY_OF_MONTH))</li>
1614     *  <li>February 28, 2008 with Calendar.MONTH as fragment will return 28
1615     *   (equivalent to calendar.get(Calendar.DAY_OF_MONTH))</li>
1616     *  <li>January 28, 2008 with Calendar.YEAR as fragment will return 28
1617     *   (equivalent to calendar.get(Calendar.DAY_OF_YEAR))</li>
1618     *  <li>February 28, 2008 with Calendar.YEAR as fragment will return 59
1619     *   (equivalent to calendar.get(Calendar.DAY_OF_YEAR))</li>
1620     *  <li>January 28, 2008 with Calendar.MILLISECOND as fragment will return 0
1621     *   (a millisecond cannot be split in days)</li>
1622     * </ul>
1623     *
1624     * @param calendar the calendar to work with, not null
1625     * @param fragment the {@code Calendar} field part of calendar to calculate
1626     * @return number of days within the fragment of date
1627     * @throws IllegalArgumentException if the date is <code>null</code> or
1628     * fragment is not supported
1629     * @since 2.4
1630     */
1631    public static long getFragmentInDays(final Calendar calendar, final int fragment) {
1632        return getFragment(calendar, fragment, TimeUnit.DAYS);
1633    }
1634
1635    /**
1636     * Gets a Date fragment for any unit.
1637     *
1638     * @param date the date to work with, not null
1639     * @param fragment the Calendar field part of date to calculate
1640     * @param unit the time unit
1641     * @return number of units within the fragment of the date
1642     * @throws IllegalArgumentException if the date is <code>null</code> or
1643     * fragment is not supported
1644     * @since 2.4
1645     */
1646    private static long getFragment(final Date date, final int fragment, final TimeUnit unit) {
1647        validateDateNotNull(date);
1648        final Calendar calendar = Calendar.getInstance();
1649        calendar.setTime(date);
1650        return getFragment(calendar, fragment, unit);
1651    }
1652
1653    /**
1654     * Gets a Calendar fragment for any unit.
1655     *
1656     * @param calendar the calendar to work with, not null
1657     * @param fragment the Calendar field part of calendar to calculate
1658     * @param unit the time unit
1659     * @return number of units within the fragment of the calendar
1660     * @throws IllegalArgumentException if the date is <code>null</code> or
1661     * fragment is not supported
1662     * @since 2.4
1663     */
1664    private static long getFragment(final Calendar calendar, final int fragment, final TimeUnit unit) {
1665        if(calendar == null) {
1666            throw  new IllegalArgumentException("The date must not be null");
1667        }
1668
1669        long result = 0;
1670
1671        final int offset = (unit == TimeUnit.DAYS) ? 0 : 1;
1672
1673        // Fragments bigger than a day require a breakdown to days
1674        switch (fragment) {
1675            case Calendar.YEAR:
1676                result += unit.convert(calendar.get(Calendar.DAY_OF_YEAR) - offset, TimeUnit.DAYS);
1677                break;
1678            case Calendar.MONTH:
1679                result += unit.convert(calendar.get(Calendar.DAY_OF_MONTH) - offset, TimeUnit.DAYS);
1680                break;
1681            default:
1682                break;
1683        }
1684
1685        switch (fragment) {
1686            // Number of days already calculated for these cases
1687            case Calendar.YEAR:
1688            case Calendar.MONTH:
1689
1690            // The rest of the valid cases
1691            case Calendar.DAY_OF_YEAR:
1692            case Calendar.DATE:
1693                result += unit.convert(calendar.get(Calendar.HOUR_OF_DAY), TimeUnit.HOURS);
1694                //$FALL-THROUGH$
1695            case Calendar.HOUR_OF_DAY:
1696                result += unit.convert(calendar.get(Calendar.MINUTE), TimeUnit.MINUTES);
1697                //$FALL-THROUGH$
1698            case Calendar.MINUTE:
1699                result += unit.convert(calendar.get(Calendar.SECOND), TimeUnit.SECONDS);
1700                //$FALL-THROUGH$
1701            case Calendar.SECOND:
1702                result += unit.convert(calendar.get(Calendar.MILLISECOND), TimeUnit.MILLISECONDS);
1703                break;
1704            case Calendar.MILLISECOND: break;//never useful
1705                default: throw new IllegalArgumentException("The fragment " + fragment + " is not supported");
1706        }
1707        return result;
1708    }
1709
1710    /**
1711     * Determines if two calendars are equal up to no more than the specified
1712     * most significant field.
1713     *
1714     * @param cal1 the first calendar, not <code>null</code>
1715     * @param cal2 the second calendar, not <code>null</code>
1716     * @param field the field from {@code Calendar}
1717     * @return <code>true</code> if equal; otherwise <code>false</code>
1718     * @throws IllegalArgumentException if any argument is <code>null</code>
1719     * @see #truncate(Calendar, int)
1720     * @see #truncatedEquals(Date, Date, int)
1721     * @since 3.0
1722     */
1723    public static boolean truncatedEquals(final Calendar cal1, final Calendar cal2, final int field) {
1724        return truncatedCompareTo(cal1, cal2, field) == 0;
1725    }
1726
1727    /**
1728     * Determines if two dates are equal up to no more than the specified
1729     * most significant field.
1730     *
1731     * @param date1 the first date, not <code>null</code>
1732     * @param date2 the second date, not <code>null</code>
1733     * @param field the field from {@code Calendar}
1734     * @return <code>true</code> if equal; otherwise <code>false</code>
1735     * @throws IllegalArgumentException if any argument is <code>null</code>
1736     * @see #truncate(Date, int)
1737     * @see #truncatedEquals(Calendar, Calendar, int)
1738     * @since 3.0
1739     */
1740    public static boolean truncatedEquals(final Date date1, final Date date2, final int field) {
1741        return truncatedCompareTo(date1, date2, field) == 0;
1742    }
1743
1744    /**
1745     * Determines how two calendars compare up to no more than the specified
1746     * most significant field.
1747     *
1748     * @param cal1 the first calendar, not <code>null</code>
1749     * @param cal2 the second calendar, not <code>null</code>
1750     * @param field the field from {@code Calendar}
1751     * @return a negative integer, zero, or a positive integer as the first
1752     * calendar is less than, equal to, or greater than the second.
1753     * @throws IllegalArgumentException if any argument is <code>null</code>
1754     * @see #truncate(Calendar, int)
1755     * @see #truncatedCompareTo(Date, Date, int)
1756     * @since 3.0
1757     */
1758    public static int truncatedCompareTo(final Calendar cal1, final Calendar cal2, final int field) {
1759        final Calendar truncatedCal1 = truncate(cal1, field);
1760        final Calendar truncatedCal2 = truncate(cal2, field);
1761        return truncatedCal1.compareTo(truncatedCal2);
1762    }
1763
1764    /**
1765     * Determines how two dates compare up to no more than the specified
1766     * most significant field.
1767     *
1768     * @param date1 the first date, not <code>null</code>
1769     * @param date2 the second date, not <code>null</code>
1770     * @param field the field from <code>Calendar</code>
1771     * @return a negative integer, zero, or a positive integer as the first
1772     * date is less than, equal to, or greater than the second.
1773     * @throws IllegalArgumentException if any argument is <code>null</code>
1774     * @see #truncate(Calendar, int)
1775     * @see #truncatedCompareTo(Date, Date, int)
1776     * @since 3.0
1777     */
1778    public static int truncatedCompareTo(final Date date1, final Date date2, final int field) {
1779        final Date truncatedDate1 = truncate(date1, field);
1780        final Date truncatedDate2 = truncate(date2, field);
1781        return truncatedDate1.compareTo(truncatedDate2);
1782    }
1783
1784    private static void validateDateNotNull(final Date date) {
1785        Validate.isTrue(date != null, "The date must not be null");
1786    }
1787
1788    //-----------------------------------------------------------------------
1789    /**
1790     * <p>Date iterator.</p>
1791     */
1792    static class DateIterator implements Iterator<Calendar> {
1793        private final Calendar endFinal;
1794        private final Calendar spot;
1795
1796        /**
1797         * Constructs a DateIterator that ranges from one date to another.
1798         *
1799         * @param startFinal start date (inclusive)
1800         * @param endFinal end date (inclusive)
1801         */
1802        DateIterator(final Calendar startFinal, final Calendar endFinal) {
1803            super();
1804            this.endFinal = endFinal;
1805            spot = startFinal;
1806            spot.add(Calendar.DATE, -1);
1807        }
1808
1809        /**
1810         * Has the iterator not reached the end date yet?
1811         *
1812         * @return <code>true</code> if the iterator has yet to reach the end date
1813         */
1814        @Override
1815        public boolean hasNext() {
1816            return spot.before(endFinal);
1817        }
1818
1819        /**
1820         * Return the next calendar in the iteration
1821         *
1822         * @return Object calendar for the next date
1823         */
1824        @Override
1825        public Calendar next() {
1826            if (spot.equals(endFinal)) {
1827                throw new NoSuchElementException();
1828            }
1829            spot.add(Calendar.DATE, 1);
1830            return (Calendar) spot.clone();
1831        }
1832
1833        /**
1834         * Always throws UnsupportedOperationException.
1835         *
1836         * @throws UnsupportedOperationException
1837         * @see java.util.Iterator#remove()
1838         */
1839        @Override
1840        public void remove() {
1841            throw new UnsupportedOperationException();
1842        }
1843    }
1844
1845}