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.LocaleUtils;
030import org.apache.commons.lang3.Validate;
031
032/**
033 * <p>A suite of utilities surrounding the use of the
034 * {@link java.util.Calendar} and {@link java.util.Date} object.</p>
035 *
036 * <p>DateUtils contains a lot of common methods considering manipulations
037 * of Dates or Calendars. Some methods require some extra explanation.
038 * The truncate, ceiling and round methods could be considered the Math.floor(),
039 * Math.ceil() or Math.round versions for dates
040 * This way date-fields will be ignored in bottom-up order.
041 * As a complement to these methods we've introduced some fragment-methods.
042 * With these methods the Date-fields will be ignored in top-down order.
043 * Since a date without a year is not a valid date, you have to decide in what
044 * kind of date-field you want your result, for instance milliseconds or days.
045 * </p>
046 * <p>
047 * Several methods are provided for adding to {@code Date} objects, of the form
048 * {@code addXXX(Date date, int amount)}. It is important to note these methods
049 * use a {@code Calendar} internally (with default time zone and locale) and may
050 * be affected by changes to daylight saving time (DST).
051 * </p>
052 *
053 * @since 2.0
054 */
055public class DateUtils {
056
057    /**
058     * Number of milliseconds in a standard second.
059     * @since 2.1
060     */
061    public static final long MILLIS_PER_SECOND = 1000;
062    /**
063     * Number of milliseconds in a standard minute.
064     * @since 2.1
065     */
066    public static final long MILLIS_PER_MINUTE = 60 * MILLIS_PER_SECOND;
067    /**
068     * Number of milliseconds in a standard hour.
069     * @since 2.1
070     */
071    public static final long MILLIS_PER_HOUR = 60 * MILLIS_PER_MINUTE;
072    /**
073     * Number of milliseconds in a standard day.
074     * @since 2.1
075     */
076    public static final long MILLIS_PER_DAY = 24 * MILLIS_PER_HOUR;
077
078    /**
079     * This is half a month, so this represents whether a date is in the top
080     * or bottom half of the month.
081     */
082    public static final int SEMI_MONTH = 1001;
083
084    private static final int[][] fields = {
085            {Calendar.MILLISECOND},
086            {Calendar.SECOND},
087            {Calendar.MINUTE},
088            {Calendar.HOUR_OF_DAY, Calendar.HOUR},
089            {Calendar.DATE, Calendar.DAY_OF_MONTH, Calendar.AM_PM
090                /* Calendar.DAY_OF_YEAR, Calendar.DAY_OF_WEEK, Calendar.DAY_OF_WEEK_IN_MONTH */
091            },
092            {Calendar.MONTH, SEMI_MONTH},
093            {Calendar.YEAR},
094            {Calendar.ERA}};
095
096    /**
097     * A week range, starting on Sunday.
098     */
099    public static final int RANGE_WEEK_SUNDAY = 1;
100    /**
101     * A week range, starting on Monday.
102     */
103    public static final int RANGE_WEEK_MONDAY = 2;
104    /**
105     * A week range, starting on the day focused.
106     */
107    public static final int RANGE_WEEK_RELATIVE = 3;
108    /**
109     * A week range, centered around the day focused.
110     */
111    public static final int RANGE_WEEK_CENTER = 4;
112    /**
113     * A month range, the week starting on Sunday.
114     */
115    public static final int RANGE_MONTH_SUNDAY = 5;
116    /**
117     * A month range, the week starting on Monday.
118     */
119    public static final int RANGE_MONTH_MONDAY = 6;
120
121    /**
122     * Calendar modification types.
123     */
124    private enum ModifyType {
125        /**
126         * Truncation.
127         */
128        TRUNCATE,
129
130        /**
131         * Rounding.
132         */
133        ROUND,
134
135        /**
136         * Ceiling.
137         */
138        CEILING
139    }
140
141    /**
142     * <p>{@code DateUtils} instances should NOT be constructed in
143     * standard programming. Instead, the static methods on the class should
144     * be used, such as {@code DateUtils.parseDate(str);}.</p>
145     *
146     * <p>This constructor is public to permit tools that require a JavaBean
147     * instance to operate.</p>
148     */
149    public DateUtils() {
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}
164     * @since 2.1
165     */
166    public static boolean isSameDay(final Date date1, final Date date2) {
167        if (date1 == null || date2 == null) {
168            throw nullDateIllegalArgumentException();
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}
188     * @since 2.1
189     */
190    public static boolean isSameDay(final Calendar cal1, final Calendar cal2) {
191        if (cal1 == null || cal2 == null) {
192            throw nullDateIllegalArgumentException();
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}
209     * @since 2.1
210     */
211    public static boolean isSameInstant(final Date date1, final Date date2) {
212        if (date1 == null || date2 == null) {
213            throw nullDateIllegalArgumentException();
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}
227     * @since 2.1
228     */
229    public static boolean isSameInstant(final Calendar cal1, final Calendar cal2) {
230        if (cal1 == null || cal2 == null) {
231            throw nullDateIllegalArgumentException();
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}
247     * @since 2.1
248     */
249    public static boolean isSameLocalTime(final Calendar cal1, final Calendar cal2) {
250        if (cal1 == null || cal2 == null) {
251            throw nullDateIllegalArgumentException();
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},
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},
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 interpreting 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(final String str, final Locale locale, final String[] parsePatterns,
365        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 = LocaleUtils.toLocale(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 NullPointerException 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 time zone 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 time zone 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}
738     * @return the different rounded date, not null
739     * @throws NullPointerException if the date is {@code null}
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 nullDateIllegalArgumentException();
745        }
746        final Calendar rounded = (Calendar) date.clone();
747        modify(rounded, field, ModifyType.ROUND);
748        return rounded;
749    }
750
751    private static IllegalArgumentException nullDateIllegalArgumentException() {
752        return new IllegalArgumentException("The date must not be null");
753    }
754
755    /**
756     * <p>Rounds a date, leaving the field specified as the most
757     * significant field.</p>
758     *
759     * <p>For example, if you had the date-time of 28 Mar 2002
760     * 13:45:01.231, if this was passed with HOUR, it would return
761     * 28 Mar 2002 14:00:00.000. If this was passed with MONTH, it
762     * would return 1 April 2002 0:00:00.000.</p>
763     *
764     * <p>For a date in a time zone that handles the change to daylight
765     * saving time, rounding to Calendar.HOUR_OF_DAY will behave as follows.
766     * Suppose daylight saving time begins at 02:00 on March 30. Rounding a
767     * date that crosses this time would produce the following values:
768     * </p>
769     * <ul>
770     * <li>March 30, 2003 01:10 rounds to March 30, 2003 01:00</li>
771     * <li>March 30, 2003 01:40 rounds to March 30, 2003 03:00</li>
772     * <li>March 30, 2003 02:10 rounds to March 30, 2003 03:00</li>
773     * <li>March 30, 2003 02:40 rounds to March 30, 2003 04:00</li>
774     * </ul>
775     *
776     * @param date  the date to work with, either {@code Date} or {@code Calendar}, not null
777     * @param field  the field from {@code Calendar} or {@code SEMI_MONTH}
778     * @return the different rounded date, not null
779     * @throws NullPointerException if the date is {@code null}
780     * @throws ClassCastException if the object type is not a {@code Date} or {@code Calendar}
781     * @throws ArithmeticException if the year is over 280 million
782     */
783    public static Date round(final Object date, final int field) {
784        if (date == null) {
785            throw nullDateIllegalArgumentException();
786        }
787        if (date instanceof Date) {
788            return round((Date) date, field);
789        } else if (date instanceof Calendar) {
790            return round((Calendar) date, field).getTime();
791        } else {
792            throw new ClassCastException("Could not round " + date);
793        }
794    }
795
796    //-----------------------------------------------------------------------
797    /**
798     * <p>Truncates a date, leaving the field specified as the most
799     * significant field.</p>
800     *
801     * <p>For example, if you had the date-time of 28 Mar 2002
802     * 13:45:01.231, if you passed with HOUR, it would return 28 Mar
803     * 2002 13:00:00.000.  If this was passed with MONTH, it would
804     * return 1 Mar 2002 0:00:00.000.</p>
805     *
806     * @param date  the date to work with, not null
807     * @param field  the field from {@code Calendar} or {@code SEMI_MONTH}
808     * @return the different truncated date, not null
809     * @throws NullPointerException if the date is {@code null}
810     * @throws ArithmeticException if the year is over 280 million
811     */
812    public static Date truncate(final Date date, final int field) {
813        validateDateNotNull(date);
814        final Calendar gval = Calendar.getInstance();
815        gval.setTime(date);
816        modify(gval, field, ModifyType.TRUNCATE);
817        return gval.getTime();
818    }
819
820    /**
821     * <p>Truncates a date, leaving the field specified as the most
822     * significant field.</p>
823     *
824     * <p>For example, if you had the date-time of 28 Mar 2002
825     * 13:45:01.231, if you passed with HOUR, it would return 28 Mar
826     * 2002 13:00:00.000.  If this was passed with MONTH, it would
827     * return 1 Mar 2002 0:00:00.000.</p>
828     *
829     * @param date  the date to work with, not null
830     * @param field  the field from {@code Calendar} or {@code SEMI_MONTH}
831     * @return the different truncated date, not null
832     * @throws NullPointerException if the date is {@code null}
833     * @throws ArithmeticException if the year is over 280 million
834     */
835    public static Calendar truncate(final Calendar date, final int field) {
836        if (date == null) {
837            throw nullDateIllegalArgumentException();
838        }
839        final Calendar truncated = (Calendar) date.clone();
840        modify(truncated, field, ModifyType.TRUNCATE);
841        return truncated;
842    }
843
844    /**
845     * <p>Truncates a date, leaving the field specified as the most
846     * significant field.</p>
847     *
848     * <p>For example, if you had the date-time of 28 Mar 2002
849     * 13:45:01.231, if you passed with HOUR, it would return 28 Mar
850     * 2002 13:00:00.000.  If this was passed with MONTH, it would
851     * return 1 Mar 2002 0:00:00.000.</p>
852     *
853     * @param date  the date to work with, either {@code Date} or {@code Calendar}, not null
854     * @param field  the field from {@code Calendar} or {@code SEMI_MONTH}
855     * @return the different truncated date, not null
856     * @throws NullPointerException if the date is {@code null}
857     * @throws ClassCastException if the object type is not a {@code Date} or {@code Calendar}
858     * @throws ArithmeticException if the year is over 280 million
859     */
860    public static Date truncate(final Object date, final int field) {
861        if (date == null) {
862            throw nullDateIllegalArgumentException();
863        }
864        if (date instanceof Date) {
865            return truncate((Date) date, field);
866        } else if (date instanceof Calendar) {
867            return truncate((Calendar) date, field).getTime();
868        } else {
869            throw new ClassCastException("Could not truncate " + date);
870        }
871    }
872
873  //-----------------------------------------------------------------------
874    /**
875     * <p>Gets a date ceiling, leaving the field specified as the most
876     * significant field.</p>
877     *
878     * <p>For example, if you had the date-time of 28 Mar 2002
879     * 13:45:01.231, if you passed with HOUR, it would return 28 Mar
880     * 2002 14:00:00.000.  If this was passed with MONTH, it would
881     * return 1 Apr 2002 0:00:00.000.</p>
882     *
883     * @param date  the date to work with, not null
884     * @param field  the field from {@code Calendar} or {@code SEMI_MONTH}
885     * @return the different ceil date, not null
886     * @throws NullPointerException if the date is {@code null}
887     * @throws ArithmeticException if the year is over 280 million
888     * @since 2.5
889     */
890    public static Date ceiling(final Date date, final int field) {
891        validateDateNotNull(date);
892        final Calendar gval = Calendar.getInstance();
893        gval.setTime(date);
894        modify(gval, field, ModifyType.CEILING);
895        return gval.getTime();
896    }
897
898    /**
899     * <p>Gets a date ceiling, leaving the field specified as the most
900     * significant field.</p>
901     *
902     * <p>For example, if you had the date-time of 28 Mar 2002
903     * 13:45:01.231, if you passed with HOUR, it would return 28 Mar
904     * 2002 14:00:00.000.  If this was passed with MONTH, it would
905     * return 1 Apr 2002 0:00:00.000.</p>
906     *
907     * @param date  the date to work with, not null
908     * @param field  the field from {@code Calendar} or {@code SEMI_MONTH}
909     * @return the different ceil date, not null
910     * @throws NullPointerException if the date is {@code null}
911     * @throws ArithmeticException if the year is over 280 million
912     * @since 2.5
913     */
914    public static Calendar ceiling(final Calendar date, final int field) {
915        if (date == null) {
916            throw nullDateIllegalArgumentException();
917        }
918        final Calendar ceiled = (Calendar) date.clone();
919        modify(ceiled, field, ModifyType.CEILING);
920        return ceiled;
921    }
922
923    /**
924     * <p>Gets a date ceiling, leaving the field specified as the most
925     * significant field.</p>
926     *
927     * <p>For example, if you had the date-time of 28 Mar 2002
928     * 13:45:01.231, if you passed with HOUR, it would return 28 Mar
929     * 2002 14:00:00.000.  If this was passed with MONTH, it would
930     * return 1 Apr 2002 0:00:00.000.</p>
931     *
932     * @param date  the date to work with, either {@code Date} or {@code Calendar}, not null
933     * @param field  the field from {@code Calendar} or {@code SEMI_MONTH}
934     * @return the different ceil date, not null
935     * @throws NullPointerException if the date is {@code null}
936     * @throws ClassCastException if the object type is not a {@code Date} or {@code Calendar}
937     * @throws ArithmeticException if the year is over 280 million
938     * @since 2.5
939     */
940    public static Date ceiling(final Object date, final int field) {
941        if (date == null) {
942            throw nullDateIllegalArgumentException();
943        }
944        if (date instanceof Date) {
945            return ceiling((Date) date, field);
946        } else if (date instanceof Calendar) {
947            return ceiling((Calendar) date, field).getTime();
948        } else {
949            throw new ClassCastException("Could not find ceiling of for type: " + date.getClass());
950        }
951    }
952
953    //-----------------------------------------------------------------------
954    /**
955     * <p>Internal calculation method.</p>
956     *
957     * @param val  the calendar, not null
958     * @param field  the field constant
959     * @param modType  type to truncate, round or ceiling
960     * @throws ArithmeticException if the year is over 280 million
961     */
962    private static void modify(final Calendar val, final int field, final ModifyType modType) {
963        if (val.get(Calendar.YEAR) > 280000000) {
964            throw new ArithmeticException("Calendar value too large for accurate calculations");
965        }
966
967        if (field == Calendar.MILLISECOND) {
968            return;
969        }
970
971        // ----------------- Fix for LANG-59 ---------------------- START ---------------
972        // see https://issues.apache.org/jira/browse/LANG-59
973        //
974        // Manually truncate milliseconds, seconds and minutes, rather than using
975        // Calendar methods.
976
977        final Date date = val.getTime();
978        long time = date.getTime();
979        boolean done = false;
980
981        // truncate milliseconds
982        final int millisecs = val.get(Calendar.MILLISECOND);
983        if (ModifyType.TRUNCATE == modType || millisecs < 500) {
984            time = time - millisecs;
985        }
986        if (field == Calendar.SECOND) {
987            done = true;
988        }
989
990        // truncate seconds
991        final int seconds = val.get(Calendar.SECOND);
992        if (!done && (ModifyType.TRUNCATE == modType || seconds < 30)) {
993            time = time - (seconds * 1000L);
994        }
995        if (field == Calendar.MINUTE) {
996            done = true;
997        }
998
999        // truncate minutes
1000        final int minutes = val.get(Calendar.MINUTE);
1001        if (!done && (ModifyType.TRUNCATE == modType || minutes < 30)) {
1002            time = time - (minutes * 60000L);
1003        }
1004
1005        // reset time
1006        if (date.getTime() != time) {
1007            date.setTime(time);
1008            val.setTime(date);
1009        }
1010        // ----------------- Fix for LANG-59 ----------------------- END ----------------
1011
1012        boolean roundUp = false;
1013        for (final int[] aField : fields) {
1014            for (final int element : aField) {
1015                if (element == field) {
1016                    //This is our field... we stop looping
1017                    if (modType == ModifyType.CEILING || modType == ModifyType.ROUND && roundUp) {
1018                        if (field == SEMI_MONTH) {
1019                            //This is a special case that's hard to generalize
1020                            //If the date is 1, we round up to 16, otherwise
1021                            //  we subtract 15 days and add 1 month
1022                            if (val.get(Calendar.DATE) == 1) {
1023                                val.add(Calendar.DATE, 15);
1024                            } else {
1025                                val.add(Calendar.DATE, -15);
1026                                val.add(Calendar.MONTH, 1);
1027                            }
1028// ----------------- Fix for LANG-440 ---------------------- START ---------------
1029                        } else if (field == Calendar.AM_PM) {
1030                            // This is a special case
1031                            // If the time is 0, we round up to 12, otherwise
1032                            //  we subtract 12 hours and add 1 day
1033                            if (val.get(Calendar.HOUR_OF_DAY) == 0) {
1034                                val.add(Calendar.HOUR_OF_DAY, 12);
1035                            } else {
1036                                val.add(Calendar.HOUR_OF_DAY, -12);
1037                                val.add(Calendar.DATE, 1);
1038                            }
1039// ----------------- Fix for LANG-440 ---------------------- END ---------------
1040                        } else {
1041                            //We need at add one to this field since the
1042                            //  last number causes us to round up
1043                            val.add(aField[0], 1);
1044                        }
1045                    }
1046                    return;
1047                }
1048            }
1049            //We have various fields that are not easy roundings
1050            int offset = 0;
1051            boolean offsetSet = false;
1052            //These are special types of fields that require different rounding rules
1053            switch (field) {
1054                case SEMI_MONTH:
1055                    if (aField[0] == Calendar.DATE) {
1056                        //If we're going to drop the DATE field's value,
1057                        //  we want to do this our own way.
1058                        //We need to subtract 1 since the date has a minimum of 1
1059                        offset = val.get(Calendar.DATE) - 1;
1060                        //If we're above 15 days adjustment, that means we're in the
1061                        //  bottom half of the month and should stay accordingly.
1062                        if (offset >= 15) {
1063                            offset -= 15;
1064                        }
1065                        //Record whether we're in the top or bottom half of that range
1066                        roundUp = offset > 7;
1067                        offsetSet = true;
1068                    }
1069                    break;
1070                case Calendar.AM_PM:
1071                    if (aField[0] == Calendar.HOUR_OF_DAY) {
1072                        //If we're going to drop the HOUR field's value,
1073                        //  we want to do this our own way.
1074                        offset = val.get(Calendar.HOUR_OF_DAY);
1075                        if (offset >= 12) {
1076                            offset -= 12;
1077                        }
1078                        roundUp = offset >= 6;
1079                        offsetSet = true;
1080                    }
1081                    break;
1082                default:
1083                    break;
1084            }
1085            if (!offsetSet) {
1086                final int min = val.getActualMinimum(aField[0]);
1087                final int max = val.getActualMaximum(aField[0]);
1088                //Calculate the offset from the minimum allowed value
1089                offset = val.get(aField[0]) - min;
1090                //Set roundUp if this is more than half way between the minimum and maximum
1091                roundUp = offset > ((max - min) / 2);
1092            }
1093            //We need to remove this field
1094            if (offset != 0) {
1095                val.set(aField[0], val.get(aField[0]) - offset);
1096            }
1097        }
1098        throw new IllegalArgumentException("The field " + field + " is not supported");
1099
1100    }
1101
1102    //-----------------------------------------------------------------------
1103    /**
1104     * <p>Constructs an {@code Iterator} over each day in a date
1105     * range defined by a focus date and range style.</p>
1106     *
1107     * <p>For instance, passing Thursday, July 4, 2002 and a
1108     * {@code RANGE_MONTH_SUNDAY} will return an {@code Iterator}
1109     * that starts with Sunday, June 30, 2002 and ends with Saturday, August 3,
1110     * 2002, returning a Calendar instance for each intermediate day.</p>
1111     *
1112     * <p>This method provides an iterator that returns Calendar objects.
1113     * The days are progressed using {@link Calendar#add(int, int)}.</p>
1114     *
1115     * @param focus  the date to work with, not null
1116     * @param rangeStyle  the style constant to use. Must be one of
1117     * {@link DateUtils#RANGE_MONTH_SUNDAY},
1118     * {@link DateUtils#RANGE_MONTH_MONDAY},
1119     * {@link DateUtils#RANGE_WEEK_SUNDAY},
1120     * {@link DateUtils#RANGE_WEEK_MONDAY},
1121     * {@link DateUtils#RANGE_WEEK_RELATIVE},
1122     * {@link DateUtils#RANGE_WEEK_CENTER}
1123     * @return the date iterator, not null, not null
1124     * @throws NullPointerException if the date is {@code null}
1125     * @throws IllegalArgumentException if the rangeStyle is invalid
1126     */
1127    public static Iterator<Calendar> iterator(final Date focus, final int rangeStyle) {
1128        validateDateNotNull(focus);
1129        final Calendar gval = Calendar.getInstance();
1130        gval.setTime(focus);
1131        return iterator(gval, rangeStyle);
1132    }
1133
1134    /**
1135     * <p>Constructs an {@code Iterator} over each day in a date
1136     * range defined by a focus date and range style.</p>
1137     *
1138     * <p>For instance, passing Thursday, July 4, 2002 and a
1139     * {@code RANGE_MONTH_SUNDAY} will return an {@code Iterator}
1140     * that starts with Sunday, June 30, 2002 and ends with Saturday, August 3,
1141     * 2002, returning a Calendar instance for each intermediate day.</p>
1142     *
1143     * <p>This method provides an iterator that returns Calendar objects.
1144     * The days are progressed using {@link Calendar#add(int, int)}.</p>
1145     *
1146     * @param focus  the date to work with, not null
1147     * @param rangeStyle  the style constant to use. Must be one of
1148     * {@link DateUtils#RANGE_MONTH_SUNDAY},
1149     * {@link DateUtils#RANGE_MONTH_MONDAY},
1150     * {@link DateUtils#RANGE_WEEK_SUNDAY},
1151     * {@link DateUtils#RANGE_WEEK_MONDAY},
1152     * {@link DateUtils#RANGE_WEEK_RELATIVE},
1153     * {@link DateUtils#RANGE_WEEK_CENTER}
1154     * @return the date iterator, not null
1155     * @throws IllegalArgumentException if the date is {@code null}
1156     * @throws IllegalArgumentException if the rangeStyle is invalid
1157     */
1158    public static Iterator<Calendar> iterator(final Calendar focus, final int rangeStyle) {
1159        if (focus == null) {
1160            throw nullDateIllegalArgumentException();
1161        }
1162        Calendar start = null;
1163        Calendar end = null;
1164        int startCutoff = Calendar.SUNDAY;
1165        int endCutoff = Calendar.SATURDAY;
1166        switch (rangeStyle) {
1167            case RANGE_MONTH_SUNDAY:
1168            case RANGE_MONTH_MONDAY:
1169                //Set start to the first of the month
1170                start = truncate(focus, Calendar.MONTH);
1171                //Set end to the last of the month
1172                end = (Calendar) start.clone();
1173                end.add(Calendar.MONTH, 1);
1174                end.add(Calendar.DATE, -1);
1175                //Loop start back to the previous sunday or monday
1176                if (rangeStyle == RANGE_MONTH_MONDAY) {
1177                    startCutoff = Calendar.MONDAY;
1178                    endCutoff = Calendar.SUNDAY;
1179                }
1180                break;
1181            case RANGE_WEEK_SUNDAY:
1182            case RANGE_WEEK_MONDAY:
1183            case RANGE_WEEK_RELATIVE:
1184            case RANGE_WEEK_CENTER:
1185                //Set start and end to the current date
1186                start = truncate(focus, Calendar.DATE);
1187                end = truncate(focus, Calendar.DATE);
1188                switch (rangeStyle) {
1189                    case RANGE_WEEK_SUNDAY:
1190                        //already set by default
1191                        break;
1192                    case RANGE_WEEK_MONDAY:
1193                        startCutoff = Calendar.MONDAY;
1194                        endCutoff = Calendar.SUNDAY;
1195                        break;
1196                    case RANGE_WEEK_RELATIVE:
1197                        startCutoff = focus.get(Calendar.DAY_OF_WEEK);
1198                        endCutoff = startCutoff - 1;
1199                        break;
1200                    case RANGE_WEEK_CENTER:
1201                        startCutoff = focus.get(Calendar.DAY_OF_WEEK) - 3;
1202                        endCutoff = focus.get(Calendar.DAY_OF_WEEK) + 3;
1203                        break;
1204                    default:
1205                        break;
1206                }
1207                break;
1208            default:
1209                throw new IllegalArgumentException("The range style " + rangeStyle + " is not valid.");
1210        }
1211        if (startCutoff < Calendar.SUNDAY) {
1212            startCutoff += 7;
1213        }
1214        if (startCutoff > Calendar.SATURDAY) {
1215            startCutoff -= 7;
1216        }
1217        if (endCutoff < Calendar.SUNDAY) {
1218            endCutoff += 7;
1219        }
1220        if (endCutoff > Calendar.SATURDAY) {
1221            endCutoff -= 7;
1222        }
1223        while (start.get(Calendar.DAY_OF_WEEK) != startCutoff) {
1224            start.add(Calendar.DATE, -1);
1225        }
1226        while (end.get(Calendar.DAY_OF_WEEK) != endCutoff) {
1227            end.add(Calendar.DATE, 1);
1228        }
1229        return new DateIterator(start, end);
1230    }
1231
1232    /**
1233     * <p>Constructs an {@code Iterator} over each day in a date
1234     * range defined by a focus date and range style.</p>
1235     *
1236     * <p>For instance, passing Thursday, July 4, 2002 and a
1237     * {@code RANGE_MONTH_SUNDAY} will return an {@code Iterator}
1238     * that starts with Sunday, June 30, 2002 and ends with Saturday, August 3,
1239     * 2002, returning a Calendar instance for each intermediate day.</p>
1240     *
1241     * @param focus  the date to work with, either {@code Date} or {@code Calendar}, not null
1242     * @param rangeStyle  the style constant to use. Must be one of the range
1243     * styles listed for the {@link #iterator(Calendar, int)} method.
1244     * @return the date iterator, not null
1245     * @throws IllegalArgumentException if the date is {@code null}
1246     * @throws ClassCastException if the object type is not a {@code Date} or {@code Calendar}
1247     */
1248    public static Iterator<?> iterator(final Object focus, final int rangeStyle) {
1249        if (focus == null) {
1250            throw nullDateIllegalArgumentException();
1251        }
1252        if (focus instanceof Date) {
1253            return iterator((Date) focus, rangeStyle);
1254        } else if (focus instanceof Calendar) {
1255            return iterator((Calendar) focus, rangeStyle);
1256        } else {
1257            throw new ClassCastException("Could not iterate based on " + focus);
1258        }
1259    }
1260
1261    /**
1262     * <p>Returns the number of milliseconds within the
1263     * fragment. All datefields greater than the fragment will be ignored.</p>
1264     *
1265     * <p>Asking the milliseconds of any date will only return the number of milliseconds
1266     * of the current second (resulting in a number between 0 and 999). This
1267     * method will retrieve the number of milliseconds for any fragment.
1268     * For example, if you want to calculate the number of milliseconds past today,
1269     * your fragment is Calendar.DATE or Calendar.DAY_OF_YEAR. The result will
1270     * be all milliseconds of the past hour(s), minutes(s) and second(s).</p>
1271     *
1272     * <p>Valid fragments are: Calendar.YEAR, Calendar.MONTH, both
1273     * Calendar.DAY_OF_YEAR and Calendar.DATE, Calendar.HOUR_OF_DAY,
1274     * Calendar.MINUTE, Calendar.SECOND and Calendar.MILLISECOND
1275     * A fragment less than or equal to a SECOND field will return 0.</p>
1276     *
1277     * <ul>
1278     *  <li>January 1, 2008 7:15:10.538 with Calendar.SECOND as fragment will return 538</li>
1279     *  <li>January 6, 2008 7:15:10.538 with Calendar.SECOND as fragment will return 538</li>
1280     *  <li>January 6, 2008 7:15:10.538 with Calendar.MINUTE as fragment will return 10538 (10*1000 + 538)</li>
1281     *  <li>January 16, 2008 7:15:10.538 with Calendar.MILLISECOND as fragment will return 0
1282     *   (a millisecond cannot be split in milliseconds)</li>
1283     * </ul>
1284     *
1285     * @param date the date to work with, not null
1286     * @param fragment the {@code Calendar} field part of date to calculate
1287     * @return number of milliseconds within the fragment of date
1288     * @throws IllegalArgumentException if the date is {@code null} or
1289     * fragment is not supported
1290     * @since 2.4
1291     */
1292    public static long getFragmentInMilliseconds(final Date date, final int fragment) {
1293        return getFragment(date, fragment, TimeUnit.MILLISECONDS);
1294    }
1295
1296    /**
1297     * <p>Returns the number of seconds within the
1298     * fragment. All datefields greater than the fragment will be ignored.</p>
1299     *
1300     * <p>Asking the seconds of any date will only return the number of seconds
1301     * of the current minute (resulting in a number between 0 and 59). This
1302     * method will retrieve the number of seconds for any fragment.
1303     * For example, if you want to calculate the number of seconds past today,
1304     * your fragment is Calendar.DATE or Calendar.DAY_OF_YEAR. The result will
1305     * be all seconds of the past hour(s) and minutes(s).</p>
1306     *
1307     * <p>Valid fragments are: Calendar.YEAR, Calendar.MONTH, both
1308     * Calendar.DAY_OF_YEAR and Calendar.DATE, Calendar.HOUR_OF_DAY,
1309     * Calendar.MINUTE, Calendar.SECOND and Calendar.MILLISECOND
1310     * A fragment less than or equal to a SECOND field will return 0.</p>
1311     *
1312     * <ul>
1313     *  <li>January 1, 2008 7:15:10.538 with Calendar.MINUTE as fragment will return 10
1314     *   (equivalent to deprecated date.getSeconds())</li>
1315     *  <li>January 6, 2008 7:15:10.538 with Calendar.MINUTE as fragment will return 10
1316     *   (equivalent to deprecated date.getSeconds())</li>
1317     *  <li>January 6, 2008 7:15:10.538 with Calendar.DAY_OF_YEAR as fragment will return 26110
1318     *   (7*3600 + 15*60 + 10)</li>
1319     *  <li>January 16, 2008 7:15:10.538 with Calendar.MILLISECOND as fragment will return 0
1320     *   (a millisecond cannot be split in seconds)</li>
1321     * </ul>
1322     *
1323     * @param date the date to work with, not null
1324     * @param fragment the {@code Calendar} field part of date to calculate
1325     * @return number of seconds within the fragment of date
1326     * @throws IllegalArgumentException if the date is {@code null} or
1327     * fragment is not supported
1328     * @since 2.4
1329     */
1330    public static long getFragmentInSeconds(final Date date, final int fragment) {
1331        return getFragment(date, fragment, TimeUnit.SECONDS);
1332    }
1333
1334    /**
1335     * <p>Returns the number of minutes within the
1336     * fragment. All datefields greater than the fragment will be ignored.</p>
1337     *
1338     * <p>Asking the minutes of any date will only return the number of minutes
1339     * of the current hour (resulting in a number between 0 and 59). This
1340     * method will retrieve the number of minutes for any fragment.
1341     * For example, if you want to calculate the number of minutes past this month,
1342     * your fragment is Calendar.MONTH. The result will be all minutes of the
1343     * past day(s) and hour(s).</p>
1344     *
1345     * <p>Valid fragments are: Calendar.YEAR, Calendar.MONTH, both
1346     * Calendar.DAY_OF_YEAR and Calendar.DATE, Calendar.HOUR_OF_DAY,
1347     * Calendar.MINUTE, Calendar.SECOND and Calendar.MILLISECOND
1348     * A fragment less than or equal to a MINUTE field will return 0.</p>
1349     *
1350     * <ul>
1351     *  <li>January 1, 2008 7:15:10.538 with Calendar.HOUR_OF_DAY as fragment will return 15
1352     *   (equivalent to deprecated date.getMinutes())</li>
1353     *  <li>January 6, 2008 7:15:10.538 with Calendar.HOUR_OF_DAY as fragment will return 15
1354     *   (equivalent to deprecated date.getMinutes())</li>
1355     *  <li>January 1, 2008 7:15:10.538 with Calendar.MONTH as fragment will return 15</li>
1356     *  <li>January 6, 2008 7:15:10.538 with Calendar.MONTH as fragment will return 435 (7*60 + 15)</li>
1357     *  <li>January 16, 2008 7:15:10.538 with Calendar.MILLISECOND as fragment will return 0
1358     *   (a millisecond cannot be split in minutes)</li>
1359     * </ul>
1360     *
1361     * @param date the date to work with, not null
1362     * @param fragment the {@code Calendar} field part of date to calculate
1363     * @return number of minutes within the fragment of date
1364     * @throws IllegalArgumentException if the date is {@code null} or
1365     * fragment is not supported
1366     * @since 2.4
1367     */
1368    public static long getFragmentInMinutes(final Date date, final int fragment) {
1369        return getFragment(date, fragment, TimeUnit.MINUTES);
1370    }
1371
1372    /**
1373     * <p>Returns the number of hours within the
1374     * fragment. All datefields greater than the fragment will be ignored.</p>
1375     *
1376     * <p>Asking the hours of any date will only return the number of hours
1377     * of the current day (resulting in a number between 0 and 23). This
1378     * method will retrieve the number of hours for any fragment.
1379     * For example, if you want to calculate the number of hours past this month,
1380     * your fragment is Calendar.MONTH. The result will be all hours of the
1381     * past day(s).</p>
1382     *
1383     * <p>Valid fragments are: Calendar.YEAR, Calendar.MONTH, both
1384     * Calendar.DAY_OF_YEAR and Calendar.DATE, Calendar.HOUR_OF_DAY,
1385     * Calendar.MINUTE, Calendar.SECOND and Calendar.MILLISECOND
1386     * A fragment less than or equal to a HOUR field will return 0.</p>
1387     *
1388     * <ul>
1389     *  <li>January 1, 2008 7:15:10.538 with Calendar.DAY_OF_YEAR as fragment will return 7
1390     *   (equivalent to deprecated date.getHours())</li>
1391     *  <li>January 6, 2008 7:15:10.538 with Calendar.DAY_OF_YEAR as fragment will return 7
1392     *   (equivalent to deprecated date.getHours())</li>
1393     *  <li>January 1, 2008 7:15:10.538 with Calendar.MONTH as fragment will return 7</li>
1394     *  <li>January 6, 2008 7:15:10.538 with Calendar.MONTH as fragment will return 127 (5*24 + 7)</li>
1395     *  <li>January 16, 2008 7:15:10.538 with Calendar.MILLISECOND as fragment will return 0
1396     *   (a millisecond cannot be split in hours)</li>
1397     * </ul>
1398     *
1399     * @param date the date to work with, not null
1400     * @param fragment the {@code Calendar} field part of date to calculate
1401     * @return number of hours within the fragment of date
1402     * @throws IllegalArgumentException if the date is {@code null} or
1403     * fragment is not supported
1404     * @since 2.4
1405     */
1406    public static long getFragmentInHours(final Date date, final int fragment) {
1407        return getFragment(date, fragment, TimeUnit.HOURS);
1408    }
1409
1410    /**
1411     * <p>Returns the number of days within the
1412     * fragment. All datefields greater than the fragment will be ignored.</p>
1413     *
1414     * <p>Asking the days of any date will only return the number of days
1415     * of the current month (resulting in a number between 1 and 31). This
1416     * method will retrieve the number of days for any fragment.
1417     * For example, if you want to calculate the number of days past this year,
1418     * your fragment is Calendar.YEAR. The result will be all days of the
1419     * past month(s).</p>
1420     *
1421     * <p>Valid fragments are: Calendar.YEAR, Calendar.MONTH, both
1422     * Calendar.DAY_OF_YEAR and Calendar.DATE, Calendar.HOUR_OF_DAY,
1423     * Calendar.MINUTE, Calendar.SECOND and Calendar.MILLISECOND
1424     * A fragment less than or equal to a DAY field will return 0.</p>
1425     *
1426     * <ul>
1427     *  <li>January 28, 2008 with Calendar.MONTH as fragment will return 28
1428     *   (equivalent to deprecated date.getDay())</li>
1429     *  <li>February 28, 2008 with Calendar.MONTH as fragment will return 28
1430     *   (equivalent to deprecated date.getDay())</li>
1431     *  <li>January 28, 2008 with Calendar.YEAR as fragment will return 28</li>
1432     *  <li>February 28, 2008 with Calendar.YEAR as fragment will return 59</li>
1433     *  <li>January 28, 2008 with Calendar.MILLISECOND as fragment will return 0
1434     *   (a millisecond cannot be split in days)</li>
1435     * </ul>
1436     *
1437     * @param date the date to work with, not null
1438     * @param fragment the {@code Calendar} field part of date to calculate
1439     * @return number of days  within the fragment of date
1440     * @throws IllegalArgumentException if the date is {@code null} or
1441     * fragment is not supported
1442     * @since 2.4
1443     */
1444    public static long getFragmentInDays(final Date date, final int fragment) {
1445        return getFragment(date, fragment, TimeUnit.DAYS);
1446    }
1447
1448    /**
1449     * <p>Returns the number of milliseconds within the
1450     * fragment. All datefields greater than the fragment will be ignored.</p>
1451     *
1452     * <p>Asking the milliseconds of any date will only return the number of milliseconds
1453     * of the current second (resulting in a number between 0 and 999). This
1454     * method will retrieve the number of milliseconds for any fragment.
1455     * For example, if you want to calculate the number of seconds past today,
1456     * your fragment is Calendar.DATE or Calendar.DAY_OF_YEAR. The result will
1457     * be all seconds of the past hour(s), minutes(s) and second(s).</p>
1458     *
1459     * <p>Valid fragments are: Calendar.YEAR, Calendar.MONTH, both
1460     * Calendar.DAY_OF_YEAR and Calendar.DATE, Calendar.HOUR_OF_DAY,
1461     * Calendar.MINUTE, Calendar.SECOND and Calendar.MILLISECOND
1462     * A fragment less than or equal to a MILLISECOND field will return 0.</p>
1463     *
1464     * <ul>
1465     *  <li>January 1, 2008 7:15:10.538 with Calendar.SECOND as fragment will return 538
1466     *   (equivalent to calendar.get(Calendar.MILLISECOND))</li>
1467     *  <li>January 6, 2008 7:15:10.538 with Calendar.SECOND as fragment will return 538
1468     *   (equivalent to calendar.get(Calendar.MILLISECOND))</li>
1469     *  <li>January 6, 2008 7:15:10.538 with Calendar.MINUTE as fragment will return 10538
1470     *   (10*1000 + 538)</li>
1471     *  <li>January 16, 2008 7:15:10.538 with Calendar.MILLISECOND as fragment will return 0
1472     *   (a millisecond cannot be split in milliseconds)</li>
1473     * </ul>
1474     *
1475     * @param calendar the calendar to work with, not null
1476     * @param fragment the {@code Calendar} field part of calendar to calculate
1477     * @return number of milliseconds within the fragment of date
1478     * @throws IllegalArgumentException if the date is {@code null} or
1479     * fragment is not supported
1480     * @since 2.4
1481     */
1482  public static long getFragmentInMilliseconds(final Calendar calendar, final int fragment) {
1483    return getFragment(calendar, fragment, TimeUnit.MILLISECONDS);
1484  }
1485    /**
1486     * <p>Returns the number of seconds within the
1487     * fragment. All datefields greater than the fragment will be ignored.</p>
1488     *
1489     * <p>Asking the seconds of any date will only return the number of seconds
1490     * of the current minute (resulting in a number between 0 and 59). This
1491     * method will retrieve the number of seconds for any fragment.
1492     * For example, if you want to calculate the number of seconds past today,
1493     * your fragment is Calendar.DATE or Calendar.DAY_OF_YEAR. The result will
1494     * be all seconds of the past hour(s) and minutes(s).</p>
1495     *
1496     * <p>Valid fragments are: Calendar.YEAR, Calendar.MONTH, both
1497     * Calendar.DAY_OF_YEAR and Calendar.DATE, Calendar.HOUR_OF_DAY,
1498     * Calendar.MINUTE, Calendar.SECOND and Calendar.MILLISECOND
1499     * A fragment less than or equal to a SECOND field will return 0.</p>
1500     *
1501     * <ul>
1502     *  <li>January 1, 2008 7:15:10.538 with Calendar.MINUTE as fragment will return 10
1503     *   (equivalent to calendar.get(Calendar.SECOND))</li>
1504     *  <li>January 6, 2008 7:15:10.538 with Calendar.MINUTE as fragment will return 10
1505     *   (equivalent to calendar.get(Calendar.SECOND))</li>
1506     *  <li>January 6, 2008 7:15:10.538 with Calendar.DAY_OF_YEAR as fragment will return 26110
1507     *   (7*3600 + 15*60 + 10)</li>
1508     *  <li>January 16, 2008 7:15:10.538 with Calendar.MILLISECOND as fragment will return 0
1509     *   (a millisecond cannot be split in seconds)</li>
1510     * </ul>
1511     *
1512     * @param calendar the calendar to work with, not null
1513     * @param fragment the {@code Calendar} field part of calendar to calculate
1514     * @return number of seconds within the fragment of date
1515     * @throws IllegalArgumentException if the date is {@code null} or
1516     * fragment is not supported
1517     * @since 2.4
1518     */
1519    public static long getFragmentInSeconds(final Calendar calendar, final int fragment) {
1520        return getFragment(calendar, fragment, TimeUnit.SECONDS);
1521    }
1522
1523    /**
1524     * <p>Returns the number of minutes within the
1525     * fragment. All datefields greater than the fragment will be ignored.</p>
1526     *
1527     * <p>Asking the minutes of any date will only return the number of minutes
1528     * of the current hour (resulting in a number between 0 and 59). This
1529     * method will retrieve the number of minutes for any fragment.
1530     * For example, if you want to calculate the number of minutes past this month,
1531     * your fragment is Calendar.MONTH. The result will be all minutes of the
1532     * past day(s) and hour(s).</p>
1533     *
1534     * <p>Valid fragments are: Calendar.YEAR, Calendar.MONTH, both
1535     * Calendar.DAY_OF_YEAR and Calendar.DATE, Calendar.HOUR_OF_DAY,
1536     * Calendar.MINUTE, Calendar.SECOND and Calendar.MILLISECOND
1537     * A fragment less than or equal to a MINUTE field will return 0.</p>
1538     *
1539     * <ul>
1540     *  <li>January 1, 2008 7:15:10.538 with Calendar.HOUR_OF_DAY as fragment will return 15
1541     *   (equivalent to calendar.get(Calendar.MINUTES))</li>
1542     *  <li>January 6, 2008 7:15:10.538 with Calendar.HOUR_OF_DAY as fragment will return 15
1543     *   (equivalent to calendar.get(Calendar.MINUTES))</li>
1544     *  <li>January 1, 2008 7:15:10.538 with Calendar.MONTH as fragment will return 15</li>
1545     *  <li>January 6, 2008 7:15:10.538 with Calendar.MONTH as fragment will return 435 (7*60 + 15)</li>
1546     *  <li>January 16, 2008 7:15:10.538 with Calendar.MILLISECOND as fragment will return 0
1547     *   (a millisecond cannot be split in minutes)</li>
1548     * </ul>
1549     *
1550     * @param calendar the calendar to work with, not null
1551     * @param fragment the {@code Calendar} field part of calendar to calculate
1552     * @return number of minutes within the fragment of date
1553     * @throws IllegalArgumentException if the date is {@code null} or
1554     * fragment is not supported
1555     * @since 2.4
1556     */
1557    public static long getFragmentInMinutes(final Calendar calendar, final int fragment) {
1558        return getFragment(calendar, fragment, TimeUnit.MINUTES);
1559    }
1560
1561    /**
1562     * <p>Returns the number of hours within the
1563     * fragment. All datefields greater than the fragment will be ignored.</p>
1564     *
1565     * <p>Asking the hours of any date will only return the number of hours
1566     * of the current day (resulting in a number between 0 and 23). This
1567     * method will retrieve the number of hours for any fragment.
1568     * For example, if you want to calculate the number of hours past this month,
1569     * your fragment is Calendar.MONTH. The result will be all hours of the
1570     * past day(s).</p>
1571     *
1572     * <p>Valid fragments are: Calendar.YEAR, Calendar.MONTH, both
1573     * Calendar.DAY_OF_YEAR and Calendar.DATE, Calendar.HOUR_OF_DAY,
1574     * Calendar.MINUTE, Calendar.SECOND and Calendar.MILLISECOND
1575     * A fragment less than or equal to a HOUR field will return 0.</p>
1576     *
1577     * <ul>
1578     *  <li>January 1, 2008 7:15:10.538 with Calendar.DAY_OF_YEAR as fragment will return 7
1579     *   (equivalent to calendar.get(Calendar.HOUR_OF_DAY))</li>
1580     *  <li>January 6, 2008 7:15:10.538 with Calendar.DAY_OF_YEAR as fragment will return 7
1581     *   (equivalent to calendar.get(Calendar.HOUR_OF_DAY))</li>
1582     *  <li>January 1, 2008 7:15:10.538 with Calendar.MONTH as fragment will return 7</li>
1583     *  <li>January 6, 2008 7:15:10.538 with Calendar.MONTH as fragment will return 127 (5*24 + 7)</li>
1584     *  <li>January 16, 2008 7:15:10.538 with Calendar.MILLISECOND as fragment will return 0
1585     *   (a millisecond cannot be split in hours)</li>
1586     * </ul>
1587     *
1588     * @param calendar the calendar to work with, not null
1589     * @param fragment the {@code Calendar} field part of calendar to calculate
1590     * @return number of hours within the fragment of date
1591     * @throws IllegalArgumentException if the date is {@code null} or
1592     * fragment is not supported
1593     * @since 2.4
1594     */
1595    public static long getFragmentInHours(final Calendar calendar, final int fragment) {
1596        return getFragment(calendar, fragment, TimeUnit.HOURS);
1597    }
1598
1599    /**
1600     * <p>Returns the number of days within the
1601     * fragment. All datefields greater than the fragment will be ignored.</p>
1602     *
1603     * <p>Asking the days of any date will only return the number of days
1604     * of the current month (resulting in a number between 1 and 31). This
1605     * method will retrieve the number of days for any fragment.
1606     * For example, if you want to calculate the number of days past this year,
1607     * your fragment is Calendar.YEAR. The result will be all days of the
1608     * past month(s).</p>
1609     *
1610     * <p>Valid fragments are: Calendar.YEAR, Calendar.MONTH, both
1611     * Calendar.DAY_OF_YEAR and Calendar.DATE, Calendar.HOUR_OF_DAY,
1612     * Calendar.MINUTE, Calendar.SECOND and Calendar.MILLISECOND
1613     * A fragment less than or equal to a DAY field will return 0.</p>
1614     *
1615     * <ul>
1616     *  <li>January 28, 2008 with Calendar.MONTH as fragment will return 28
1617     *   (equivalent to calendar.get(Calendar.DAY_OF_MONTH))</li>
1618     *  <li>February 28, 2008 with Calendar.MONTH as fragment will return 28
1619     *   (equivalent to calendar.get(Calendar.DAY_OF_MONTH))</li>
1620     *  <li>January 28, 2008 with Calendar.YEAR as fragment will return 28
1621     *   (equivalent to calendar.get(Calendar.DAY_OF_YEAR))</li>
1622     *  <li>February 28, 2008 with Calendar.YEAR as fragment will return 59
1623     *   (equivalent to calendar.get(Calendar.DAY_OF_YEAR))</li>
1624     *  <li>January 28, 2008 with Calendar.MILLISECOND as fragment will return 0
1625     *   (a millisecond cannot be split in days)</li>
1626     * </ul>
1627     *
1628     * @param calendar the calendar to work with, not null
1629     * @param fragment the {@code Calendar} field part of calendar to calculate
1630     * @return number of days within the fragment of date
1631     * @throws IllegalArgumentException if the date is {@code null} or
1632     * fragment is not supported
1633     * @since 2.4
1634     */
1635    public static long getFragmentInDays(final Calendar calendar, final int fragment) {
1636        return getFragment(calendar, fragment, TimeUnit.DAYS);
1637    }
1638
1639    /**
1640     * Gets a Date fragment for any unit.
1641     *
1642     * @param date the date to work with, not null
1643     * @param fragment the Calendar field part of date to calculate
1644     * @param unit the time unit
1645     * @return number of units within the fragment of the date
1646     * @throws NullPointerException if the date is {@code null}
1647     * @throws IllegalArgumentException if fragment is not supported
1648     * @since 2.4
1649     */
1650    private static long getFragment(final Date date, final int fragment, final TimeUnit unit) {
1651        validateDateNotNull(date);
1652        final Calendar calendar = Calendar.getInstance();
1653        calendar.setTime(date);
1654        return getFragment(calendar, fragment, unit);
1655    }
1656
1657    /**
1658     * Gets a Calendar fragment for any unit.
1659     *
1660     * @param calendar the calendar to work with, not null
1661     * @param fragment the Calendar field part of calendar to calculate
1662     * @param unit the time unit
1663     * @return number of units within the fragment of the calendar
1664     * @throws IllegalArgumentException if the date is {@code null} or
1665     * fragment is not supported
1666     * @since 2.4
1667     */
1668    private static long getFragment(final Calendar calendar, final int fragment, final TimeUnit unit) {
1669        if (calendar == null) {
1670            throw  nullDateIllegalArgumentException();
1671        }
1672
1673        long result = 0;
1674
1675        final int offset = (unit == TimeUnit.DAYS) ? 0 : 1;
1676
1677        // Fragments bigger than a day require a breakdown to days
1678        switch (fragment) {
1679            case Calendar.YEAR:
1680                result += unit.convert(calendar.get(Calendar.DAY_OF_YEAR) - offset, TimeUnit.DAYS);
1681                break;
1682            case Calendar.MONTH:
1683                result += unit.convert(calendar.get(Calendar.DAY_OF_MONTH) - offset, TimeUnit.DAYS);
1684                break;
1685            default:
1686                break;
1687        }
1688
1689        switch (fragment) {
1690            // Number of days already calculated for these cases
1691            case Calendar.YEAR:
1692            case Calendar.MONTH:
1693
1694            // The rest of the valid cases
1695            case Calendar.DAY_OF_YEAR:
1696            case Calendar.DATE:
1697                result += unit.convert(calendar.get(Calendar.HOUR_OF_DAY), TimeUnit.HOURS);
1698                //$FALL-THROUGH$
1699            case Calendar.HOUR_OF_DAY:
1700                result += unit.convert(calendar.get(Calendar.MINUTE), TimeUnit.MINUTES);
1701                //$FALL-THROUGH$
1702            case Calendar.MINUTE:
1703                result += unit.convert(calendar.get(Calendar.SECOND), TimeUnit.SECONDS);
1704                //$FALL-THROUGH$
1705            case Calendar.SECOND:
1706                result += unit.convert(calendar.get(Calendar.MILLISECOND), TimeUnit.MILLISECONDS);
1707                break;
1708            case Calendar.MILLISECOND: break; //never useful
1709                default: throw new IllegalArgumentException("The fragment " + fragment + " is not supported");
1710        }
1711        return result;
1712    }
1713
1714    /**
1715     * Determines if two calendars are equal up to no more than the specified
1716     * most significant field.
1717     *
1718     * @param cal1 the first calendar, not {@code null}
1719     * @param cal2 the second calendar, not {@code null}
1720     * @param field the field from {@code Calendar}
1721     * @return {@code true} if equal; otherwise {@code false}
1722     * @throws IllegalArgumentException if any argument is {@code null}
1723     * @see #truncate(Calendar, int)
1724     * @see #truncatedEquals(Date, Date, int)
1725     * @since 3.0
1726     */
1727    public static boolean truncatedEquals(final Calendar cal1, final Calendar cal2, final int field) {
1728        return truncatedCompareTo(cal1, cal2, field) == 0;
1729    }
1730
1731    /**
1732     * Determines if two dates are equal up to no more than the specified
1733     * most significant field.
1734     *
1735     * @param date1 the first date, not {@code null}
1736     * @param date2 the second date, not {@code null}
1737     * @param field the field from {@code Calendar}
1738     * @return {@code true} if equal; otherwise {@code false}
1739     * @throws IllegalArgumentException if any argument is {@code null}
1740     * @see #truncate(Date, int)
1741     * @see #truncatedEquals(Calendar, Calendar, int)
1742     * @since 3.0
1743     */
1744    public static boolean truncatedEquals(final Date date1, final Date date2, final int field) {
1745        return truncatedCompareTo(date1, date2, field) == 0;
1746    }
1747
1748    /**
1749     * Determines how two calendars compare up to no more than the specified
1750     * most significant field.
1751     *
1752     * @param cal1 the first calendar, not {@code null}
1753     * @param cal2 the second calendar, not {@code null}
1754     * @param field the field from {@code Calendar}
1755     * @return a negative integer, zero, or a positive integer as the first
1756     * calendar is less than, equal to, or greater than the second.
1757     * @throws IllegalArgumentException if any argument is {@code null}
1758     * @see #truncate(Calendar, int)
1759     * @see #truncatedCompareTo(Date, Date, int)
1760     * @since 3.0
1761     */
1762    public static int truncatedCompareTo(final Calendar cal1, final Calendar cal2, final int field) {
1763        final Calendar truncatedCal1 = truncate(cal1, field);
1764        final Calendar truncatedCal2 = truncate(cal2, field);
1765        return truncatedCal1.compareTo(truncatedCal2);
1766    }
1767
1768    /**
1769     * Determines how two dates compare up to no more than the specified
1770     * most significant field.
1771     *
1772     * @param date1 the first date, not {@code null}
1773     * @param date2 the second date, not {@code null}
1774     * @param field the field from {@code Calendar}
1775     * @return a negative integer, zero, or a positive integer as the first
1776     * date is less than, equal to, or greater than the second.
1777     * @throws IllegalArgumentException if any argument is {@code null}
1778     * @see #truncate(Calendar, int)
1779     * @see #truncatedCompareTo(Date, Date, int)
1780     * @since 3.0
1781     */
1782    public static int truncatedCompareTo(final Date date1, final Date date2, final int field) {
1783        final Date truncatedDate1 = truncate(date1, field);
1784        final Date truncatedDate2 = truncate(date2, field);
1785        return truncatedDate1.compareTo(truncatedDate2);
1786    }
1787
1788    private static void validateDateNotNull(final Date date) {
1789        Validate.notNull(date, "date");
1790    }
1791
1792    //-----------------------------------------------------------------------
1793    /**
1794     * <p>Date iterator.</p>
1795     */
1796    static class DateIterator implements Iterator<Calendar> {
1797        private final Calendar endFinal;
1798        private final Calendar spot;
1799
1800        /**
1801         * Constructs a DateIterator that ranges from one date to another.
1802         *
1803         * @param startFinal start date (inclusive)
1804         * @param endFinal end date (inclusive)
1805         */
1806        DateIterator(final Calendar startFinal, final Calendar endFinal) {
1807            this.endFinal = endFinal;
1808            spot = startFinal;
1809            spot.add(Calendar.DATE, -1);
1810        }
1811
1812        /**
1813         * Has the iterator not reached the end date yet?
1814         *
1815         * @return {@code true} if the iterator has yet to reach the end date
1816         */
1817        @Override
1818        public boolean hasNext() {
1819            return spot.before(endFinal);
1820        }
1821
1822        /**
1823         * Returns the next calendar in the iteration
1824         *
1825         * @return Object calendar for the next date
1826         */
1827        @Override
1828        public Calendar next() {
1829            if (spot.equals(endFinal)) {
1830                throw new NoSuchElementException();
1831            }
1832            spot.add(Calendar.DATE, 1);
1833            return (Calendar) spot.clone();
1834        }
1835
1836        /**
1837         * Always throws UnsupportedOperationException.
1838         *
1839         * @throws UnsupportedOperationException Always thrown.
1840         * @see java.util.Iterator#remove()
1841         */
1842        @Override
1843        public void remove() {
1844            throw new UnsupportedOperationException();
1845        }
1846    }
1847
1848}