/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You under the Apache License, Version 2.0
    * (the "License"); you may not use this file except in compliance with
    * the License.  You may obtain a copy of the License at
    * 
    *      http://www.apache.org/licenses/LICENSE-2.0
   * 
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.commons.lang3.time;
  
  import java.text.ParseException;
  import java.text.ParsePosition;
  import java.text.SimpleDateFormat;
  import java.util.Calendar;
  import java.util.Date;
  import java.util.Iterator;
  import java.util.Locale;
  import java.util.NoSuchElementException;
  import java.util.concurrent.TimeUnit;
  
  /**
   * <p>A suite of utilities surrounding the use of the
   * {@link java.util.Calendar} and {@link java.util.Date} object.</p>
   * 
   * <p>DateUtils contains a lot of common methods considering manipulations
   * of Dates or Calendars. Some methods require some extra explanation.
   * The truncate, ceiling and round methods could be considered the Math.floor(),
   * Math.ceil() or Math.round versions for dates
   * This way date-fields will be ignored in bottom-up order.
   * As a complement to these methods we've introduced some fragment-methods.
   * With these methods the Date-fields will be ignored in top-down order.
   * Since a date without a year is not a valid date, you have to decide in what
   * kind of date-field you want your result, for instance milliseconds or days.
   * </p>
   * <p>
   * Several methods are provided for adding to {@code Date} objects, of the form 
   * {@code addXXX(Date date, int amount)}. It is important to note these methods 
   * use a {@code Calendar} internally (with default timezone and locale) and may
   * be affected by changes to daylight saving time (DST).
   * </p>
   *
   * @since 2.0
   * @version $Id$
   */
  public class DateUtils {
  
      /**
       * Number of milliseconds in a standard second.
       * @since 2.1
       */
      public static final long MILLIS_PER_SECOND = 1000;
      /**
       * Number of milliseconds in a standard minute.
       * @since 2.1
       */
      public static final long MILLIS_PER_MINUTE = 60 * MILLIS_PER_SECOND;
      /**
       * Number of milliseconds in a standard hour.
       * @since 2.1
       */
      public static final long MILLIS_PER_HOUR = 60 * MILLIS_PER_MINUTE;
      /**
       * Number of milliseconds in a standard day.
       * @since 2.1
       */
      public static final long MILLIS_PER_DAY = 24 * MILLIS_PER_HOUR;
  
      /**
       * This is half a month, so this represents whether a date is in the top
       * or bottom half of the month.
       */
      public static final int SEMI_MONTH = 1001;
  
      private static final int[][] fields = {
              {Calendar.MILLISECOND},
              {Calendar.SECOND},
              {Calendar.MINUTE},
              {Calendar.HOUR_OF_DAY, Calendar.HOUR},
              {Calendar.DATE, Calendar.DAY_OF_MONTH, Calendar.AM_PM 
                  /* Calendar.DAY_OF_YEAR, Calendar.DAY_OF_WEEK, Calendar.DAY_OF_WEEK_IN_MONTH */
              },
              {Calendar.MONTH, DateUtils.SEMI_MONTH},
              {Calendar.YEAR},
              {Calendar.ERA}};
  
      /**
       * A week range, starting on Sunday.
       */
      public static final int RANGE_WEEK_SUNDAY = 1;
      /**
       * A week range, starting on Monday.
      */
     public static final int RANGE_WEEK_MONDAY = 2;
     /**
      * A week range, starting on the day focused.
      */
     public static final int RANGE_WEEK_RELATIVE = 3;
     /**
      * A week range, centered around the day focused.
      */
     public static final int RANGE_WEEK_CENTER = 4;
     /**
      * A month range, the week starting on Sunday.
      */
     public static final int RANGE_MONTH_SUNDAY = 5;
     /**
      * A month range, the week starting on Monday.
      */
     public static final int RANGE_MONTH_MONDAY = 6;
 
     /**
      * Calendar modification types.
      */
     private enum ModifyType {
         /**
          * Truncation.
          */
         TRUNCATE,
         
         /**
          * Rounding. 
          */
         ROUND,
         
         /**
          * Ceiling. 
          */
         CEILING
     }
 
     /**
      * <p>{@code DateUtils} instances should NOT be constructed in
      * standard programming. Instead, the static methods on the class should
      * be used, such as {@code DateUtils.parseDate(str);}.</p>
      *
      * <p>This constructor is public to permit tools that require a JavaBean
      * instance to operate.</p>
      */
     public DateUtils() {
         super();
     }
 
     //-----------------------------------------------------------------------
     /**
      * <p>Checks if two date objects are on the same day ignoring time.</p>
      *
      * <p>28 Mar 2002 13:45 and 28 Mar 2002 06:01 would return true.
      * 28 Mar 2002 13:45 and 12 Mar 2002 13:45 would return false.
      * </p>
      * 
      * @param date1  the first date, not altered, not null
      * @param date2  the second date, not altered, not null
      * @return true if they represent the same day
      * @throws IllegalArgumentException if either date is <code>null</code>
      * @since 2.1
      */
     public static boolean isSameDay(final Date date1, final Date date2) {
         if (date1 == null || date2 == null) {
             throw new IllegalArgumentException("The date must not be null");
         }
         final Calendar cal1 = Calendar.getInstance();
         cal1.setTime(date1);
         final Calendar cal2 = Calendar.getInstance();
         cal2.setTime(date2);
         return isSameDay(cal1, cal2);
     }
 
     /**
      * <p>Checks if two calendar objects are on the same day ignoring time.</p>
      *
      * <p>28 Mar 2002 13:45 and 28 Mar 2002 06:01 would return true.
      * 28 Mar 2002 13:45 and 12 Mar 2002 13:45 would return false.
      * </p>
      * 
      * @param cal1  the first calendar, not altered, not null
      * @param cal2  the second calendar, not altered, not null
      * @return true if they represent the same day
      * @throws IllegalArgumentException if either calendar is <code>null</code>
      * @since 2.1
      */
     public static boolean isSameDay(final Calendar cal1, final Calendar cal2) {
         if (cal1 == null || cal2 == null) {
             throw new IllegalArgumentException("The date must not be null");
         }
         return (cal1.get(Calendar.ERA) == cal2.get(Calendar.ERA) &&
                 cal1.get(Calendar.YEAR) == cal2.get(Calendar.YEAR) &&
                 cal1.get(Calendar.DAY_OF_YEAR) == cal2.get(Calendar.DAY_OF_YEAR));
     }
 
     //-----------------------------------------------------------------------
     /**
      * <p>Checks if two date objects represent the same instant in time.</p>
      *
      * <p>This method compares the long millisecond time of the two objects.</p>
      * 
      * @param date1  the first date, not altered, not null
      * @param date2  the second date, not altered, not null
      * @return true if they represent the same millisecond instant
      * @throws IllegalArgumentException if either date is <code>null</code>
      * @since 2.1
      */
     public static boolean isSameInstant(final Date date1, final Date date2) {
         if (date1 == null || date2 == null) {
             throw new IllegalArgumentException("The date must not be null");
         }
         return date1.getTime() == date2.getTime();
     }
 
     /**
      * <p>Checks if two calendar objects represent the same instant in time.</p>
      *
      * <p>This method compares the long millisecond time of the two objects.</p>
      * 
      * @param cal1  the first calendar, not altered, not null
      * @param cal2  the second calendar, not altered, not null
      * @return true if they represent the same millisecond instant
      * @throws IllegalArgumentException if either date is <code>null</code>
      * @since 2.1
      */
     public static boolean isSameInstant(final Calendar cal1, final Calendar cal2) {
         if (cal1 == null || cal2 == null) {
             throw new IllegalArgumentException("The date must not be null");
         }
         return cal1.getTime().getTime() == cal2.getTime().getTime();
     }
 
     //-----------------------------------------------------------------------
     /**
      * <p>Checks if two calendar objects represent the same local time.</p>
      *
      * <p>This method compares the values of the fields of the two objects.
      * In addition, both calendars must be the same of the same type.</p>
      * 
      * @param cal1  the first calendar, not altered, not null
      * @param cal2  the second calendar, not altered, not null
      * @return true if they represent the same millisecond instant
      * @throws IllegalArgumentException if either date is <code>null</code>
      * @since 2.1
      */
     public static boolean isSameLocalTime(final Calendar cal1, final Calendar cal2) {
         if (cal1 == null || cal2 == null) {
             throw new IllegalArgumentException("The date must not be null");
         }
         return (cal1.get(Calendar.MILLISECOND) == cal2.get(Calendar.MILLISECOND) &&
                 cal1.get(Calendar.SECOND) == cal2.get(Calendar.SECOND) &&
                 cal1.get(Calendar.MINUTE) == cal2.get(Calendar.MINUTE) &&
                 cal1.get(Calendar.HOUR_OF_DAY) == cal2.get(Calendar.HOUR_OF_DAY) &&
                 cal1.get(Calendar.DAY_OF_YEAR) == cal2.get(Calendar.DAY_OF_YEAR) &&
                 cal1.get(Calendar.YEAR) == cal2.get(Calendar.YEAR) &&
                 cal1.get(Calendar.ERA) == cal2.get(Calendar.ERA) &&
                 cal1.getClass() == cal2.getClass());
     }
 
     //-----------------------------------------------------------------------
     /**
      * <p>Parses a string representing a date by trying a variety of different parsers.</p>
      * 
      * <p>The parse will try each parse pattern in turn.
      * A parse is only deemed successful if it parses the whole of the input string.
      * If no parse patterns match, a ParseException is thrown.</p>
      * The parser will be lenient toward the parsed date.
      * 
      * @param str  the date to parse, not null
      * @param parsePatterns  the date format patterns to use, see SimpleDateFormat, not null
      * @return the parsed date
      * @throws IllegalArgumentException if the date string or pattern array is null
      * @throws ParseException if none of the date patterns were suitable (or there were none)
      */
     public static Date parseDate(final String str, final String... parsePatterns) throws ParseException {
         return parseDate(str, null, parsePatterns);
     }
     
     //-----------------------------------------------------------------------
     /**
      * <p>Parses a string representing a date by trying a variety of different parsers,
      * using the default date format symbols for the given locale.</p>
      * 
      * <p>The parse will try each parse pattern in turn.
      * A parse is only deemed successful if it parses the whole of the input string.
      * If no parse patterns match, a ParseException is thrown.</p>
      * The parser will be lenient toward the parsed date.
      * 
      * @param str  the date to parse, not null
      * @param locale the locale whose date format symbols should be used. If <code>null</code>,
      * the system locale is used (as per {@link #parseDate(String, String...)}).
      * @param parsePatterns  the date format patterns to use, see SimpleDateFormat, not null
      * @return the parsed date
      * @throws IllegalArgumentException if the date string or pattern array is null
      * @throws ParseException if none of the date patterns were suitable (or there were none)
      * @since 3.2
      */
     public static Date parseDate(final String str, final Locale locale, final String... parsePatterns) throws ParseException {
         return parseDateWithLeniency(str, locale, parsePatterns, true);
     }    
 
   //-----------------------------------------------------------------------
     /**
      * <p>Parses a string representing a date by trying a variety of different parsers.</p>
      * 
      * <p>The parse will try each parse pattern in turn.
      * A parse is only deemed successful if it parses the whole of the input string.
      * If no parse patterns match, a ParseException is thrown.</p>
      * The parser parses strictly - it does not allow for dates such as "February 942, 1996". 
      * 
      * @param str  the date to parse, not null
      * @param parsePatterns  the date format patterns to use, see SimpleDateFormat, not null
      * @return the parsed date
      * @throws IllegalArgumentException if the date string or pattern array is null
      * @throws ParseException if none of the date patterns were suitable
      * @since 2.5
      */
     public static Date parseDateStrictly(final String str, final String... parsePatterns) throws ParseException {
         return parseDateStrictly(str, null, parsePatterns);
     }
 
     /**
      * <p>Parses a string representing a date by trying a variety of different parsers,
      * using the default date format symbols for the given locale..</p>
      * 
      * <p>The parse will try each parse pattern in turn.
      * A parse is only deemed successful if it parses the whole of the input string.
      * If no parse patterns match, a ParseException is thrown.</p>
      * The parser parses strictly - it does not allow for dates such as "February 942, 1996". 
      * 
      * @param str  the date to parse, not null
      * @param locale the locale whose date format symbols should be used. If <code>null</code>,
      * the system locale is used (as per {@link #parseDateStrictly(String, String...)}).
      * @param parsePatterns  the date format patterns to use, see SimpleDateFormat, not null
      * @return the parsed date
      * @throws IllegalArgumentException if the date string or pattern array is null
      * @throws ParseException if none of the date patterns were suitable
      * @since 3.2
      */
     public static Date parseDateStrictly(final String str, final Locale locale, final String... parsePatterns) throws ParseException {
         return parseDateWithLeniency(str, null, parsePatterns, false);
     }    
 
     /**
      * <p>Parses a string representing a date by trying a variety of different parsers.</p>
      * 
      * <p>The parse will try each parse pattern in turn.
      * A parse is only deemed successful if it parses the whole of the input string.
      * If no parse patterns match, a ParseException is thrown.</p>
      * 
      * @param str  the date to parse, not null
      * @param locale the locale to use when interpretting the pattern, can be null in which
      * case the default system locale is used
      * @param parsePatterns  the date format patterns to use, see SimpleDateFormat, not null
      * @param lenient Specify whether or not date/time parsing is to be lenient.
      * @return the parsed date
      * @throws IllegalArgumentException if the date string or pattern array is null
      * @throws ParseException if none of the date patterns were suitable
      * @see java.util.Calendar#isLenient()
      */
     private static Date parseDateWithLeniency(
             final String str, final Locale locale, final String[] parsePatterns, final boolean lenient) throws ParseException {
         if (str == null || parsePatterns == null) {
             throw new IllegalArgumentException("Date and Patterns must not be null");
         }
         
         SimpleDateFormat parser;
         if (locale == null) {
             parser = new SimpleDateFormat();
         } else {
             parser = new SimpleDateFormat("", locale);
         }
         
         parser.setLenient(lenient);
         final ParsePosition pos = new ParsePosition(0);
         for (final String parsePattern : parsePatterns) {
 
             String pattern = parsePattern;
 
             // LANG-530 - need to make sure 'ZZ' output doesn't get passed to SimpleDateFormat
             if (parsePattern.endsWith("ZZ")) {
                 pattern = pattern.substring(0, pattern.length() - 1);
             }
             
             parser.applyPattern(pattern);
             pos.setIndex(0);
 
             String str2 = str;
             // LANG-530 - need to make sure 'ZZ' output doesn't hit SimpleDateFormat as it will ParseException
             if (parsePattern.endsWith("ZZ")) {
                 str2 = str.replaceAll("([-+][0-9][0-9]):([0-9][0-9])$", "$1$2"); 
             }
 
             final Date date = parser.parse(str2, pos);
             if (date != null && pos.getIndex() == str2.length()) {
                 return date;
             }
         }
         throw new ParseException("Unable to parse the date: " + str, -1);
     }
 
     //-----------------------------------------------------------------------
     /**
      * Adds a number of years to a date returning a new object.
      * The original {@code Date} is unchanged.
      *
      * @param date  the date, not null
      * @param amount  the amount to add, may be negative
      * @return the new {@code Date} with the amount added
      * @throws IllegalArgumentException if the date is null
      */
     public static Date addYears(final Date date, final int amount) {
         return add(date, Calendar.YEAR, amount);
     }
 
     //-----------------------------------------------------------------------
     /**
      * Adds a number of months to a date returning a new object.
      * The original {@code Date} is unchanged.
      *
      * @param date  the date, not null
      * @param amount  the amount to add, may be negative
      * @return the new {@code Date} with the amount added
      * @throws IllegalArgumentException if the date is null
      */
     public static Date addMonths(final Date date, final int amount) {
         return add(date, Calendar.MONTH, amount);
     }
 
     //-----------------------------------------------------------------------
     /**
      * Adds a number of weeks to a date returning a new object.
      * The original {@code Date} is unchanged.
      *
      * @param date  the date, not null
      * @param amount  the amount to add, may be negative
      * @return the new {@code Date} with the amount added
      * @throws IllegalArgumentException if the date is null
      */
     public static Date addWeeks(final Date date, final int amount) {
         return add(date, Calendar.WEEK_OF_YEAR, amount);
     }
 
     //-----------------------------------------------------------------------
     /**
      * Adds a number of days to a date returning a new object.
      * The original {@code Date} is unchanged.
      *
      * @param date  the date, not null
      * @param amount  the amount to add, may be negative
      * @return the new {@code Date} with the amount added
      * @throws IllegalArgumentException if the date is null
      */
     public static Date addDays(final Date date, final int amount) {
         return add(date, Calendar.DAY_OF_MONTH, amount);
     }
 
     //-----------------------------------------------------------------------
     /**
      * Adds a number of hours to a date returning a new object.
      * The original {@code Date} is unchanged.
      *
      * @param date  the date, not null
      * @param amount  the amount to add, may be negative
      * @return the new {@code Date} with the amount added
      * @throws IllegalArgumentException if the date is null
      */
     public static Date addHours(final Date date, final int amount) {
         return add(date, Calendar.HOUR_OF_DAY, amount);
     }
 
     //-----------------------------------------------------------------------
     /**
      * Adds a number of minutes to a date returning a new object.
      * The original {@code Date} is unchanged.
      *
      * @param date  the date, not null
      * @param amount  the amount to add, may be negative
      * @return the new {@code Date} with the amount added
      * @throws IllegalArgumentException if the date is null
      */
     public static Date addMinutes(final Date date, final int amount) {
         return add(date, Calendar.MINUTE, amount);
     }
 
     //-----------------------------------------------------------------------
     /**
      * Adds a number of seconds to a date returning a new object.
      * The original {@code Date} is unchanged.
      *
      * @param date  the date, not null
      * @param amount  the amount to add, may be negative
      * @return the new {@code Date} with the amount added
      * @throws IllegalArgumentException if the date is null
      */
     public static Date addSeconds(final Date date, final int amount) {
         return add(date, Calendar.SECOND, amount);
     }
 
     //-----------------------------------------------------------------------
     /**
      * Adds a number of milliseconds to a date returning a new object.
      * The original {@code Date} is unchanged.
      *
      * @param date  the date, not null
      * @param amount  the amount to add, may be negative
      * @return the new {@code Date} with the amount added
      * @throws IllegalArgumentException if the date is null
      */
     public static Date addMilliseconds(final Date date, final int amount) {
         return add(date, Calendar.MILLISECOND, amount);
     }
 
     //-----------------------------------------------------------------------
     /**
      * Adds to a date returning a new object.
      * The original {@code Date} is unchanged.
      *
      * @param date  the date, not null
      * @param calendarField  the calendar field to add to
      * @param amount  the amount to add, may be negative
      * @return the new {@code Date} with the amount added
      * @throws IllegalArgumentException if the date is null
      */
     private static Date add(final Date date, final int calendarField, final int amount) {
         if (date == null) {
             throw new IllegalArgumentException("The date must not be null");
         }
         final Calendar c = Calendar.getInstance();
         c.setTime(date);
         c.add(calendarField, amount);
         return c.getTime();
     }
     
     //-----------------------------------------------------------------------
     /**
      * Sets the years field to a date returning a new object.
      * The original {@code Date} is unchanged.
      *
      * @param date  the date, not null
      * @param amount the amount to set
      * @return a new {@code Date} set with the specified value
      * @throws IllegalArgumentException if the date is null
      * @since 2.4
      */
     public static Date setYears(final Date date, final int amount) {
         return set(date, Calendar.YEAR, amount);
     }
 
     //-----------------------------------------------------------------------
     /**
      * Sets the months field to a date returning a new object.
      * The original {@code Date} is unchanged.
      *
      * @param date  the date, not null
      * @param amount the amount to set
      * @return a new {@code Date} set with the specified value
      * @throws IllegalArgumentException if the date is null
      * @since 2.4
      */
     public static Date setMonths(final Date date, final int amount) {
         return set(date, Calendar.MONTH, amount);
     }
 
     //-----------------------------------------------------------------------
     /**
      * Sets the day of month field to a date returning a new object.
      * The original {@code Date} is unchanged.
      *
      * @param date  the date, not null
      * @param amount the amount to set
      * @return a new {@code Date} set with the specified value
      * @throws IllegalArgumentException if the date is null
      * @since 2.4
      */
     public static Date setDays(final Date date, final int amount) {
         return set(date, Calendar.DAY_OF_MONTH, amount);
     }
 
     //-----------------------------------------------------------------------
     /**
      * Sets the hours field to a date returning a new object.  Hours range 
      * from  0-23.
      * The original {@code Date} is unchanged.
      *
      * @param date  the date, not null
      * @param amount the amount to set
      * @return a new {@code Date} set with the specified value
      * @throws IllegalArgumentException if the date is null
      * @since 2.4
      */
     public static Date setHours(final Date date, final int amount) {
         return set(date, Calendar.HOUR_OF_DAY, amount);
     }
 
     //-----------------------------------------------------------------------
     /**
      * Sets the minute field to a date returning a new object.
      * The original {@code Date} is unchanged.
      *
      * @param date  the date, not null
      * @param amount the amount to set
      * @return a new {@code Date} set with the specified value
      * @throws IllegalArgumentException if the date is null
      * @since 2.4
      */
     public static Date setMinutes(final Date date, final int amount) {
         return set(date, Calendar.MINUTE, amount);
     }
     
     //-----------------------------------------------------------------------
     /**
      * Sets the seconds field to a date returning a new object.
      * The original {@code Date} is unchanged.
      *
      * @param date  the date, not null
      * @param amount the amount to set
      * @return a new {@code Date} set with the specified value
      * @throws IllegalArgumentException if the date is null
      * @since 2.4
      */
     public static Date setSeconds(final Date date, final int amount) {
         return set(date, Calendar.SECOND, amount);
     }
 
     //-----------------------------------------------------------------------
     /**
      * Sets the miliseconds field to a date returning a new object.
      * The original {@code Date} is unchanged.
      *
      * @param date  the date, not null
      * @param amount the amount to set
      * @return a new {@code Date} set with the specified value
      * @throws IllegalArgumentException if the date is null
      * @since 2.4
      */
     public static Date setMilliseconds(final Date date, final int amount) {
         return set(date, Calendar.MILLISECOND, amount);
     } 
     
     //-----------------------------------------------------------------------
     /**
      * Sets the specified field to a date returning a new object.  
      * This does not use a lenient calendar.
      * The original {@code Date} is unchanged.
      *
      * @param date  the date, not null
      * @param calendarField  the {@code Calendar} field to set the amount to
      * @param amount the amount to set
      * @return a new {@code Date} set with the specified value
      * @throws IllegalArgumentException if the date is null
      * @since 2.4
      */
     private static Date set(final Date date, final int calendarField, final int amount) {
         if (date == null) {
             throw new IllegalArgumentException("The date must not be null");
         }
         // getInstance() returns a new object, so this method is thread safe.
         final Calendar c = Calendar.getInstance();
         c.setLenient(false);
         c.setTime(date);
         c.set(calendarField, amount);
         return c.getTime();
     }   
 
     //-----------------------------------------------------------------------
     /**
      * Converts a {@code Date} into a {@code Calendar}. 
      * 
      * @param date the date to convert to a Calendar
      * @return the created Calendar
      * @throws NullPointerException if null is passed in
      * @since 3.0
      */
     public static Calendar toCalendar(final Date date) {
         final Calendar c = Calendar.getInstance();
         c.setTime(date);
         return c;
     }
     
     //-----------------------------------------------------------------------
     /**
      * <p>Rounds a date, leaving the field specified as the most
      * significant field.</p>
      *
      * <p>For example, if you had the date-time of 28 Mar 2002
      * 13:45:01.231, if this was passed with HOUR, it would return
      * 28 Mar 2002 14:00:00.000. If this was passed with MONTH, it
      * would return 1 April 2002 0:00:00.000.</p>
      * 
      * <p>For a date in a timezone that handles the change to daylight
      * saving time, rounding to Calendar.HOUR_OF_DAY will behave as follows.
      * Suppose daylight saving time begins at 02:00 on March 30. Rounding a 
      * date that crosses this time would produce the following values:
      * </p>
      * <ul>
      * <li>March 30, 2003 01:10 rounds to March 30, 2003 01:00</li>
      * <li>March 30, 2003 01:40 rounds to March 30, 2003 03:00</li>
      * <li>March 30, 2003 02:10 rounds to March 30, 2003 03:00</li>
      * <li>March 30, 2003 02:40 rounds to March 30, 2003 04:00</li>
      * </ul>
      * 
      * @param date  the date to work with, not null
      * @param field  the field from {@code Calendar} or {@code SEMI_MONTH}
      * @return the different rounded date, not null
      * @throws ArithmeticException if the year is over 280 million
      */
     public static Date round(final Date date, final int field) {
         if (date == null) {
             throw new IllegalArgumentException("The date must not be null");
         }
         final Calendar gval = Calendar.getInstance();
         gval.setTime(date);
         modify(gval, field, ModifyType.ROUND);
         return gval.getTime();
     }
 
     /**
      * <p>Rounds a date, leaving the field specified as the most
      * significant field.</p>
      *
      * <p>For example, if you had the date-time of 28 Mar 2002
      * 13:45:01.231, if this was passed with HOUR, it would return
      * 28 Mar 2002 14:00:00.000. If this was passed with MONTH, it
      * would return 1 April 2002 0:00:00.000.</p>
      * 
      * <p>For a date in a timezone that handles the change to daylight
      * saving time, rounding to Calendar.HOUR_OF_DAY will behave as follows.
      * Suppose daylight saving time begins at 02:00 on March 30. Rounding a 
      * date that crosses this time would produce the following values:
      * </p>
      * <ul>
      * <li>March 30, 2003 01:10 rounds to March 30, 2003 01:00</li>
      * <li>March 30, 2003 01:40 rounds to March 30, 2003 03:00</li>
      * <li>March 30, 2003 02:10 rounds to March 30, 2003 03:00</li>
      * <li>March 30, 2003 02:40 rounds to March 30, 2003 04:00</li>
      * </ul>
      * 
      * @param date  the date to work with, not null
      * @param field  the field from {@code Calendar} or <code>SEMI_MONTH</code>
      * @return the different rounded date, not null
      * @throws IllegalArgumentException if the date is <code>null</code>
      * @throws ArithmeticException if the year is over 280 million
      */
     public static Calendar round(final Calendar date, final int field) {
         if (date == null) {
             throw new IllegalArgumentException("The date must not be null");
         }
         final Calendar rounded = (Calendar) date.clone();
         modify(rounded, field, ModifyType.ROUND);
         return rounded;
     }
 
     /**
      * <p>Rounds a date, leaving the field specified as the most
      * significant field.</p>
      *
      * <p>For example, if you had the date-time of 28 Mar 2002
      * 13:45:01.231, if this was passed with HOUR, it would return
      * 28 Mar 2002 14:00:00.000. If this was passed with MONTH, it
      * would return 1 April 2002 0:00:00.000.</p>
      * 
      * <p>For a date in a timezone that handles the change to daylight
      * saving time, rounding to Calendar.HOUR_OF_DAY will behave as follows.
      * Suppose daylight saving time begins at 02:00 on March 30. Rounding a 
      * date that crosses this time would produce the following values:
      * </p>
      * <ul>
      * <li>March 30, 2003 01:10 rounds to March 30, 2003 01:00</li>
      * <li>March 30, 2003 01:40 rounds to March 30, 2003 03:00</li>
      * <li>March 30, 2003 02:10 rounds to March 30, 2003 03:00</li>
      * <li>March 30, 2003 02:40 rounds to March 30, 2003 04:00</li>
      * </ul>
      * 
      * @param date  the date to work with, either {@code Date} or {@code Calendar}, not null
      * @param field  the field from {@code Calendar} or <code>SEMI_MONTH</code>
      * @return the different rounded date, not null
      * @throws IllegalArgumentException if the date is <code>null</code>
      * @throws ClassCastException if the object type is not a {@code Date} or {@code Calendar}
      * @throws ArithmeticException if the year is over 280 million
      */
     public static Date round(final Object date, final int field) {
         if (date == null) {
             throw new IllegalArgumentException("The date must not be null");
         }
         if (date instanceof Date) {
             return round((Date) date, field);
         } else if (date instanceof Calendar) {
             return round((Calendar) date, field).getTime();
         } else {
             throw new ClassCastException("Could not round " + date);
         }
     }
 
     //-----------------------------------------------------------------------
     /**
      * <p>Truncates a date, leaving the field specified as the most
      * significant field.</p>
      *
      * <p>For example, if you had the date-time of 28 Mar 2002
      * 13:45:01.231, if you passed with HOUR, it would return 28 Mar
      * 2002 13:00:00.000.  If this was passed with MONTH, it would
      * return 1 Mar 2002 0:00:00.000.</p>
      * 
      * @param date  the date to work with, not null
      * @param field  the field from {@code Calendar} or <code>SEMI_MONTH</code>
      * @return the different truncated date, not null
      * @throws IllegalArgumentException if the date is <code>null</code>
      * @throws ArithmeticException if the year is over 280 million
      */
     public static Date truncate(final Date date, final int field) {
         if (date == null) {
             throw new IllegalArgumentException("The date must not be null");
         }
         final Calendar gval = Calendar.getInstance();
         gval.setTime(date);
         modify(gval, field, ModifyType.TRUNCATE);
         return gval.getTime();
     }
 
     /**
      * <p>Truncates a date, leaving the field specified as the most
      * significant field.</p>
      *
      * <p>For example, if you had the date-time of 28 Mar 2002
      * 13:45:01.231, if you passed with HOUR, it would return 28 Mar
      * 2002 13:00:00.000.  If this was passed with MONTH, it would
      * return 1 Mar 2002 0:00:00.000.</p>
      * 
      * @param date  the date to work with, not null
      * @param field  the field from {@code Calendar} or <code>SEMI_MONTH</code>
      * @return the different truncated date, not null
      * @throws IllegalArgumentException if the date is <code>null</code>
      * @throws ArithmeticException if the year is over 280 million
      */
     public static Calendar truncate(final Calendar date, final int field) {
         if (date == null) {
             throw new IllegalArgumentException("The date must not be null");
         }
         final Calendar truncated = (Calendar) date.clone();
         modify(truncated, field, ModifyType.TRUNCATE);
         return truncated;
     }
 
     /**
      * <p>Truncates a date, leaving the field specified as the most
      * significant field.</p>
      *
      * <p>For example, if you had the date-time of 28 Mar 2002
      * 13:45:01.231, if you passed with HOUR, it would return 28 Mar
      * 2002 13:00:00.000.  If this was passed with MONTH, it would
      * return 1 Mar 2002 0:00:00.000.</p>
      * 
      * @param date  the date to work with, either {@code Date} or {@code Calendar}, not null
      * @param field  the field from {@code Calendar} or <code>SEMI_MONTH</code>
      * @return the different truncated date, not null
      * @throws IllegalArgumentException if the date is <code>null</code>
      * @throws ClassCastException if the object type is not a {@code Date} or {@code Calendar}
      * @throws ArithmeticException if the year is over 280 million
      */
     public static Date truncate(final Object date, final int field) {
         if (date == null) {
             throw new IllegalArgumentException("The date must not be null");
         }
         if (date instanceof Date) {
             return truncate((Date) date, field);
         } else if (date instanceof Calendar) {
             return truncate((Calendar) date, field).getTime();
         } else {
             throw new ClassCastException("Could not truncate " + date);
         }
     }
     
   //-----------------------------------------------------------------------
     /**
      * <p>Gets a date ceiling, leaving the field specified as the most
      * significant field.</p>
      *
      * <p>For example, if you had the date-time of 28 Mar 2002
      * 13:45:01.231, if you passed with HOUR, it would return 28 Mar
      * 2002 14:00:00.000.  If this was passed with MONTH, it would
      * return 1 Apr 2002 0:00:00.000.</p>
      * 
      * @param date  the date to work with, not null
      * @param field  the field from {@code Calendar} or <code>SEMI_MONTH</code>
      * @return the different ceil date, not null
      * @throws IllegalArgumentException if the date is <code>null</code>
      * @throws ArithmeticException if the year is over 280 million
      * @since 2.5
      */
     public static Date ceiling(final Date date, final int field) {
         if (date == null) {
             throw new IllegalArgumentException("The date must not be null");
         }
         final Calendar gval = Calendar.getInstance();
         gval.setTime(date);
         modify(gval, field, ModifyType.CEILING);
         return gval.getTime();
     }
 
     /**
      * <p>Gets a date ceiling, leaving the field specified as the most
      * significant field.</p>
      *
      * <p>For example, if you had the date-time of 28 Mar 2002
      * 13:45:01.231, if you passed with HOUR, it would return 28 Mar
      * 2002 14:00:00.000.  If this was passed with MONTH, it would
      * return 1 Apr 2002 0:00:00.000.</p>
      * 
      * @param date  the date to work with, not null
      * @param field  the field from {@code Calendar} or <code>SEMI_MONTH</code>
      * @return the different ceil date, not null
      * @throws IllegalArgumentException if the date is <code>null</code>
      * @throws ArithmeticException if the year is over 280 million
      * @since 2.5
      */
     public static Calendar ceiling(final Calendar date, final int field) {
         if (date == null) {
             throw new IllegalArgumentException("The date must not be null");
         }
         final Calendar ceiled = (Calendar) date.clone();
         modify(ceiled, field, ModifyType.CEILING);
         return ceiled;
     }
 
     /**
      * <p>Gets a date ceiling, leaving the field specified as the most
      * significant field.</p>
      *
      * <p>For example, if you had the date-time of 28 Mar 2002
      * 13:45:01.231, if you passed with HOUR, it would return 28 Mar
      * 2002 14:00:00.000.  If this was passed with MONTH, it would
      * return 1 Apr 2002 0:00:00.000.</p>
      * 
      * @param date  the date to work with, either {@code Date} or {@code Calendar}, not null
      * @param field  the field from {@code Calendar} or <code>SEMI_MONTH</code>
      * @return the different ceil date, not null
      * @throws IllegalArgumentException if the date is <code>null</code>
      * @throws ClassCastException if the object type is not a {@code Date} or {@code Calendar}
      * @throws ArithmeticException if the year is over 280 million
      * @since 2.5
      */
     public static Date ceiling(final Object date, final int field) {
         if (date == null) {
             throw new IllegalArgumentException("The date must not be null");
         }
         if (date instanceof Date) {
             return ceiling((Date) date, field);
         } else if (date instanceof Calendar) {
             return ceiling((Calendar) date, field).getTime();
         } else {
             throw new ClassCastException("Could not find ceiling of for type: " + date.getClass());
         }
     }
 
     //-----------------------------------------------------------------------
     /**
      * <p>Internal calculation method.</p>
      * 
      * @param val  the calendar, not null
      * @param field  the field constant
      * @param modType  type to truncate, round or ceiling
      * @throws ArithmeticException if the year is over 280 million
      */
     private static void modify(final Calendar val, final int field, final ModifyType modType) {
         if (val.get(Calendar.YEAR) > 280000000) {
             throw new ArithmeticException("Calendar value too large for accurate calculations");
         }
         
         if (field == Calendar.MILLISECOND) {
             return;
         }
 
         // ----------------- Fix for LANG-59 ---------------------- START ---------------
         // see http://issues.apache.org/jira/browse/LANG-59
         //
         // Manually truncate milliseconds, seconds and minutes, rather than using
         // Calendar methods.
 
         final Date date = val.getTime();
         long time = date.getTime();
         boolean done = false;
 
         // truncate milliseconds
         final int millisecs = val.get(Calendar.MILLISECOND);
         if (ModifyType.TRUNCATE == modType || millisecs < 500) {
             time = time - millisecs;
         }
         if (field == Calendar.SECOND) {
             done = true;
         }
 
         // truncate seconds
         final int seconds = val.get(Calendar.SECOND);
         if (!done && (ModifyType.TRUNCATE == modType || seconds < 30)) {
             time = time - (seconds * 1000L);
         }
         if (field == Calendar.MINUTE) {
             done = true;
         }
 
         // truncate minutes
         final int minutes = val.get(Calendar.MINUTE);
         if (!done && (ModifyType.TRUNCATE == modType || minutes < 30)) {
             time = time - (minutes * 60000L);
         }
 
         // reset time
         if (date.getTime() != time) {
             date.setTime(time);
             val.setTime(date);
         }
         // ----------------- Fix for LANG-59 ----------------------- END ----------------
 
         boolean roundUp = false;
         for (final int[] aField : fields) {
             for (final int element : aField) {
                 if (element == field) {
                     //This is our field... we stop looping
                     if (modType == ModifyType.CEILING || (modType == ModifyType.ROUND && roundUp)) {
                         if (field == DateUtils.SEMI_MONTH) {
                             //This is a special case that's hard to generalize
                             //If the date is 1, we round up to 16, otherwise
                             //  we subtract 15 days and add 1 month
                             if (val.get(Calendar.DATE) == 1) {
                                 val.add(Calendar.DATE, 15);
                             } else {
                                 val.add(Calendar.DATE, -15);
                                 val.add(Calendar.MONTH, 1);
                             }
 // ----------------- Fix for LANG-440 ---------------------- START ---------------
                         } else if (field == Calendar.AM_PM) {
                             // This is a special case
                             // If the time is 0, we round up to 12, otherwise
                             //  we subtract 12 hours and add 1 day
                             if (val.get(Calendar.HOUR_OF_DAY) == 0) {
                                 val.add(Calendar.HOUR_OF_DAY, 12);
                             } else {
                                 val.add(Calendar.HOUR_OF_DAY, -12);
                                 val.add(Calendar.DATE, 1);
                             }
 // ----------------- Fix for LANG-440 ---------------------- END ---------------
                         } else {
                             //We need at add one to this field since the
                             //  last number causes us to round up
                             val.add(aField[0], 1);
                         }
                     }
                     return;
                 }
             }
             //We have various fields that are not easy roundings
             int offset = 0;
             boolean offsetSet = false;
             //These are special types of fields that require different rounding rules
             switch (field) {
                 case DateUtils.SEMI_MONTH:
                     if (aField[0] == Calendar.DATE) {
                         //If we're going to drop the DATE field's value,
                         //  we want to do this our own way.
                         //We need to subtrace 1 since the date has a minimum of 1
                         offset = val.get(Calendar.DATE) - 1;
                         //If we're above 15 days adjustment, that means we're in the
                         //  bottom half of the month and should stay accordingly.
                         if (offset >= 15) {
                             offset -= 15;
                         }
                         //Record whether we're in the top or bottom half of that range
                         roundUp = offset > 7;
                         offsetSet = true;
                     }
                     break;
                 case Calendar.AM_PM:
                     if (aField[0] == Calendar.HOUR_OF_DAY) {
                         //If we're going to drop the HOUR field's value,
                         //  we want to do this our own way.
                         offset = val.get(Calendar.HOUR_OF_DAY);
                         if (offset >= 12) {
                             offset -= 12;
                         }
                         roundUp = offset >= 6;
                         offsetSet = true;
                     }
                     break;
                 default:
                     break;
             }
             if (!offsetSet) {
                 final int min = val.getActualMinimum(aField[0]);
                 final int max = val.getActualMaximum(aField[0]);
                 //Calculate the offset from the minimum allowed value
                 offset = val.get(aField[0]) - min;
                 //Set roundUp if this is more than half way between the minimum and maximum
                 roundUp = offset > ((max - min) / 2);
             }
             //We need to remove this field
             if (offset != 0) {
                 val.set(aField[0], val.get(aField[0]) - offset);
             }
         }
         throw new IllegalArgumentException("The field " + field + " is not supported");
 
     }
 
     //-----------------------------------------------------------------------
     /**
      * <p>Constructs an <code>Iterator</code> over each day in a date
      * range defined by a focus date and range style.</p>
      *
      * <p>For instance, passing Thursday, July 4, 2002 and a
      * <code>RANGE_MONTH_SUNDAY</code> will return an <code>Iterator</code>
      * that starts with Sunday, June 30, 2002 and ends with Saturday, August 3,
      * 2002, returning a Calendar instance for each intermediate day.</p>
      *
      * <p>This method provides an iterator that returns Calendar objects.
      * The days are progressed using {@link Calendar#add(int, int)}.</p>
      *
      * @param focus  the date to work with, not null
      * @param rangeStyle  the style constant to use. Must be one of
      * {@link DateUtils#RANGE_MONTH_SUNDAY}, 
      * {@link DateUtils#RANGE_MONTH_MONDAY},
      * {@link DateUtils#RANGE_WEEK_SUNDAY},
      * {@link DateUtils#RANGE_WEEK_MONDAY},
      * {@link DateUtils#RANGE_WEEK_RELATIVE},
      * {@link DateUtils#RANGE_WEEK_CENTER}
      * @return the date iterator, not null, not null
      * @throws IllegalArgumentException if the date is <code>null</code>
      * @throws IllegalArgumentException if the rangeStyle is invalid
      */
     public static Iterator<Calendar> iterator(final Date focus, final int rangeStyle) {
         if (focus == null) {
             throw new IllegalArgumentException("The date must not be null");
         }
         final Calendar gval = Calendar.getInstance();
         gval.setTime(focus);
         return iterator(gval, rangeStyle);
     }
 
     /**
      * <p>Constructs an <code>Iterator</code> over each day in a date
      * range defined by a focus date and range style.</p>
      *
      * <p>For instance, passing Thursday, July 4, 2002 and a
      * <code>RANGE_MONTH_SUNDAY</code> will return an <code>Iterator</code>
      * that starts with Sunday, June 30, 2002 and ends with Saturday, August 3,
      * 2002, returning a Calendar instance for each intermediate day.</p>
      *
      * <p>This method provides an iterator that returns Calendar objects.
      * The days are progressed using {@link Calendar#add(int, int)}.</p>
      *
      * @param focus  the date to work with, not null
      * @param rangeStyle  the style constant to use. Must be one of
      * {@link DateUtils#RANGE_MONTH_SUNDAY}, 
      * {@link DateUtils#RANGE_MONTH_MONDAY},
      * {@link DateUtils#RANGE_WEEK_SUNDAY},
      * {@link DateUtils#RANGE_WEEK_MONDAY},
      * {@link DateUtils#RANGE_WEEK_RELATIVE},
      * {@link DateUtils#RANGE_WEEK_CENTER}
      * @return the date iterator, not null
      * @throws IllegalArgumentException if the date is <code>null</code>
      * @throws IllegalArgumentException if the rangeStyle is invalid
      */
     public static Iterator<Calendar> iterator(final Calendar focus, final int rangeStyle) {
         if (focus == null) {
             throw new IllegalArgumentException("The date must not be null");
         }
         Calendar start = null;
         Calendar end = null;
         int startCutoff = Calendar.SUNDAY;
         int endCutoff = Calendar.SATURDAY;
         switch (rangeStyle) {
             case RANGE_MONTH_SUNDAY:
             case RANGE_MONTH_MONDAY:
                 //Set start to the first of the month
                 start = truncate(focus, Calendar.MONTH);
                 //Set end to the last of the month
                 end = (Calendar) start.clone();
                 end.add(Calendar.MONTH, 1);
                 end.add(Calendar.DATE, -1);
                 //Loop start back to the previous sunday or monday
                 if (rangeStyle == RANGE_MONTH_MONDAY) {
                     startCutoff = Calendar.MONDAY;
                     endCutoff = Calendar.SUNDAY;
                 }
                 break;
             case RANGE_WEEK_SUNDAY:
             case RANGE_WEEK_MONDAY:
             case RANGE_WEEK_RELATIVE:
             case RANGE_WEEK_CENTER:
                 //Set start and end to the current date
                 start = truncate(focus, Calendar.DATE);
                 end = truncate(focus, Calendar.DATE);
                 switch (rangeStyle) {
                     case RANGE_WEEK_SUNDAY:
                         //already set by default
                         break;
                     case RANGE_WEEK_MONDAY:
                         startCutoff = Calendar.MONDAY;
                         endCutoff = Calendar.SUNDAY;
                         break;
                     case RANGE_WEEK_RELATIVE:
                         startCutoff = focus.get(Calendar.DAY_OF_WEEK);
                         endCutoff = startCutoff - 1;
                         break;
                     case RANGE_WEEK_CENTER:
                         startCutoff = focus.get(Calendar.DAY_OF_WEEK) - 3;
                         endCutoff = focus.get(Calendar.DAY_OF_WEEK) + 3;
                         break;
                     default:
                         break;
                 }
                 break;
             default:
                 throw new IllegalArgumentException("The range style " + rangeStyle + " is not valid.");
         }
         if (startCutoff < Calendar.SUNDAY) {
             startCutoff += 7;
         }
         if (startCutoff > Calendar.SATURDAY) {
             startCutoff -= 7;
         }
         if (endCutoff < Calendar.SUNDAY) {
             endCutoff += 7;
         }
         if (endCutoff > Calendar.SATURDAY) {
             endCutoff -= 7;
         }
         while (start.get(Calendar.DAY_OF_WEEK) != startCutoff) {
             start.add(Calendar.DATE, -1);
         }
         while (end.get(Calendar.DAY_OF_WEEK) != endCutoff) {
             end.add(Calendar.DATE, 1);
         }
         return new DateIterator(start, end);
     }
 
     /**
      * <p>Constructs an <code>Iterator</code> over each day in a date
      * range defined by a focus date and range style.</p>
      *
      * <p>For instance, passing Thursday, July 4, 2002 and a
      * <code>RANGE_MONTH_SUNDAY</code> will return an <code>Iterator</code>
      * that starts with Sunday, June 30, 2002 and ends with Saturday, August 3,
      * 2002, returning a Calendar instance for each intermediate day.</p>
      *
      * @param focus  the date to work with, either {@code Date} or {@code Calendar}, not null
      * @param rangeStyle  the style constant to use. Must be one of the range
      * styles listed for the {@link #iterator(Calendar, int)} method.
      * @return the date iterator, not null
      * @throws IllegalArgumentException if the date is <code>null</code>
      * @throws ClassCastException if the object type is not a {@code Date} or {@code Calendar}
      */
     public static Iterator<?> iterator(final Object focus, final int rangeStyle) {
         if (focus == null) {
             throw new IllegalArgumentException("The date must not be null");
         }
         if (focus instanceof Date) {
             return iterator((Date) focus, rangeStyle);
         } else if (focus instanceof Calendar) {
             return iterator((Calendar) focus, rangeStyle);
         } else {
             throw new ClassCastException("Could not iterate based on " + focus);
         }
     }
     
     /**
      * <p>Returns the number of milliseconds within the 
      * fragment. All datefields greater than the fragment will be ignored.</p>
      * 
      * <p>Asking the milliseconds of any date will only return the number of milliseconds
      * of the current second (resulting in a number between 0 and 999). This 
      * method will retrieve the number of milliseconds for any fragment. 
      * For example, if you want to calculate the number of milliseconds past today, 
      * your fragment is Calendar.DATE or Calendar.DAY_OF_YEAR. The result will
      * be all milliseconds of the past hour(s), minutes(s) and second(s).</p>
      * 
      * <p>Valid fragments are: Calendar.YEAR, Calendar.MONTH, both 
      * Calendar.DAY_OF_YEAR and Calendar.DATE, Calendar.HOUR_OF_DAY, 
      * Calendar.MINUTE, Calendar.SECOND and Calendar.MILLISECOND
      * A fragment less than or equal to a SECOND field will return 0.</p> 
      * 
      * <ul>
      *  <li>January 1, 2008 7:15:10.538 with Calendar.SECOND as fragment will return 538</li>
      *  <li>January 6, 2008 7:15:10.538 with Calendar.SECOND as fragment will return 538</li>
      *  <li>January 6, 2008 7:15:10.538 with Calendar.MINUTE as fragment will return 10538 (10*1000 + 538)</li>
      *  <li>January 16, 2008 7:15:10.538 with Calendar.MILLISECOND as fragment will return 0
      *   (a millisecond cannot be split in milliseconds)</li>
      * </ul>
      * 
      * @param date the date to work with, not null
      * @param fragment the {@code Calendar} field part of date to calculate 
      * @return number of milliseconds within the fragment of date
      * @throws IllegalArgumentException if the date is <code>null</code> or
      * fragment is not supported
      * @since 2.4
      */
     public static long getFragmentInMilliseconds(final Date date, final int fragment) {
         return getFragment(date, fragment, TimeUnit.MILLISECONDS);    
     }
     
     /**
      * <p>Returns the number of seconds within the 
      * fragment. All datefields greater than the fragment will be ignored.</p> 
      * 
      * <p>Asking the seconds of any date will only return the number of seconds
      * of the current minute (resulting in a number between 0 and 59). This 
      * method will retrieve the number of seconds for any fragment. 
      * For example, if you want to calculate the number of seconds past today, 
      * your fragment is Calendar.DATE or Calendar.DAY_OF_YEAR. The result will
      * be all seconds of the past hour(s) and minutes(s).</p> 
      * 
      * <p>Valid fragments are: Calendar.YEAR, Calendar.MONTH, both 
      * Calendar.DAY_OF_YEAR and Calendar.DATE, Calendar.HOUR_OF_DAY, 
      * Calendar.MINUTE, Calendar.SECOND and Calendar.MILLISECOND
      * A fragment less than or equal to a SECOND field will return 0.</p> 
      * 
      * <ul>
      *  <li>January 1, 2008 7:15:10.538 with Calendar.MINUTE as fragment will return 10
      *   (equivalent to deprecated date.getSeconds())</li>
      *  <li>January 6, 2008 7:15:10.538 with Calendar.MINUTE as fragment will return 10
      *   (equivalent to deprecated date.getSeconds())</li>
      *  <li>January 6, 2008 7:15:10.538 with Calendar.DAY_OF_YEAR as fragment will return 26110
      *   (7*3600 + 15*60 + 10)</li>
      *  <li>January 16, 2008 7:15:10.538 with Calendar.MILLISECOND as fragment will return 0
      *   (a millisecond cannot be split in seconds)</li>
      * </ul>
      * 
      * @param date the date to work with, not null
      * @param fragment the {@code Calendar} field part of date to calculate 
      * @return number of seconds within the fragment of date
      * @throws IllegalArgumentException if the date is <code>null</code> or
      * fragment is not supported
      * @since 2.4
      */
     public static long getFragmentInSeconds(final Date date, final int fragment) {
         return getFragment(date, fragment, TimeUnit.SECONDS);
     }
     
     /**
      * <p>Returns the number of minutes within the 
      * fragment. All datefields greater than the fragment will be ignored.</p> 
      * 
      * <p>Asking the minutes of any date will only return the number of minutes
      * of the current hour (resulting in a number between 0 and 59). This 
      * method will retrieve the number of minutes for any fragment. 
      * For example, if you want to calculate the number of minutes past this month, 
      * your fragment is Calendar.MONTH. The result will be all minutes of the 
      * past day(s) and hour(s).</p> 
      * 
      * <p>Valid fragments are: Calendar.YEAR, Calendar.MONTH, both 
      * Calendar.DAY_OF_YEAR and Calendar.DATE, Calendar.HOUR_OF_DAY, 
      * Calendar.MINUTE, Calendar.SECOND and Calendar.MILLISECOND
      * A fragment less than or equal to a MINUTE field will return 0.</p> 
      * 
      * <ul>
      *  <li>January 1, 2008 7:15:10.538 with Calendar.HOUR_OF_DAY as fragment will return 15
      *   (equivalent to deprecated date.getMinutes())</li>
      *  <li>January 6, 2008 7:15:10.538 with Calendar.HOUR_OF_DAY as fragment will return 15
      *   (equivalent to deprecated date.getMinutes())</li>
      *  <li>January 1, 2008 7:15:10.538 with Calendar.MONTH as fragment will return 15</li>
      *  <li>January 6, 2008 7:15:10.538 with Calendar.MONTH as fragment will return 435 (7*60 + 15)</li>
      *  <li>January 16, 2008 7:15:10.538 with Calendar.MILLISECOND as fragment will return 0
      *   (a millisecond cannot be split in minutes)</li>
      * </ul>
      * 
      * @param date the date to work with, not null
      * @param fragment the {@code Calendar} field part of date to calculate 
      * @return number of minutes within the fragment of date
      * @throws IllegalArgumentException if the date is <code>null</code> or 
      * fragment is not supported
      * @since 2.4
      */
     public static long getFragmentInMinutes(final Date date, final int fragment) {
         return getFragment(date, fragment, TimeUnit.MINUTES);
     }
     
     /**
      * <p>Returns the number of hours within the 
      * fragment. All datefields greater than the fragment will be ignored.</p> 
      * 
      * <p>Asking the hours of any date will only return the number of hours
      * of the current day (resulting in a number between 0 and 23). This 
      * method will retrieve the number of hours for any fragment. 
      * For example, if you want to calculate the number of hours past this month, 
      * your fragment is Calendar.MONTH. The result will be all hours of the 
      * past day(s).</p> 
      * 
      * <p>Valid fragments are: Calendar.YEAR, Calendar.MONTH, both 
      * Calendar.DAY_OF_YEAR and Calendar.DATE, Calendar.HOUR_OF_DAY, 
      * Calendar.MINUTE, Calendar.SECOND and Calendar.MILLISECOND
      * A fragment less than or equal to a HOUR field will return 0.</p> 
      * 
      * <ul>
      *  <li>January 1, 2008 7:15:10.538 with Calendar.DAY_OF_YEAR as fragment will return 7
      *   (equivalent to deprecated date.getHours())</li>
      *  <li>January 6, 2008 7:15:10.538 with Calendar.DAY_OF_YEAR as fragment will return 7
      *   (equivalent to deprecated date.getHours())</li>
      *  <li>January 1, 2008 7:15:10.538 with Calendar.MONTH as fragment will return 7</li>
      *  <li>January 6, 2008 7:15:10.538 with Calendar.MONTH as fragment will return 127 (5*24 + 7)</li>
      *  <li>January 16, 2008 7:15:10.538 with Calendar.MILLISECOND as fragment will return 0
      *   (a millisecond cannot be split in hours)</li>
      * </ul>
      * 
      * @param date the date to work with, not null
      * @param fragment the {@code Calendar} field part of date to calculate 
      * @return number of hours within the fragment of date
      * @throws IllegalArgumentException if the date is <code>null</code> or 
      * fragment is not supported
      * @since 2.4
      */
     public static long getFragmentInHours(final Date date, final int fragment) {
         return getFragment(date, fragment, TimeUnit.HOURS);
     }
     
     /**
      * <p>Returns the number of days within the 
      * fragment. All datefields greater than the fragment will be ignored.</p> 
      * 
      * <p>Asking the days of any date will only return the number of days
      * of the current month (resulting in a number between 1 and 31). This 
      * method will retrieve the number of days for any fragment. 
      * For example, if you want to calculate the number of days past this year, 
      * your fragment is Calendar.YEAR. The result will be all days of the 
      * past month(s).</p> 
      * 
      * <p>Valid fragments are: Calendar.YEAR, Calendar.MONTH, both 
      * Calendar.DAY_OF_YEAR and Calendar.DATE, Calendar.HOUR_OF_DAY, 
      * Calendar.MINUTE, Calendar.SECOND and Calendar.MILLISECOND
      * A fragment less than or equal to a DAY field will return 0.</p> 
      *  
      * <ul>
      *  <li>January 28, 2008 with Calendar.MONTH as fragment will return 28
      *   (equivalent to deprecated date.getDay())</li>
      *  <li>February 28, 2008 with Calendar.MONTH as fragment will return 28
      *   (equivalent to deprecated date.getDay())</li>
      *  <li>January 28, 2008 with Calendar.YEAR as fragment will return 28</li>
      *  <li>February 28, 2008 with Calendar.YEAR as fragment will return 59</li>
      *  <li>January 28, 2008 with Calendar.MILLISECOND as fragment will return 0
      *   (a millisecond cannot be split in days)</li>
      * </ul>
      * 
      * @param date the date to work with, not null
      * @param fragment the {@code Calendar} field part of date to calculate 
      * @return number of days  within the fragment of date
      * @throws IllegalArgumentException if the date is <code>null</code> or 
      * fragment is not supported
      * @since 2.4
      */
     public static long getFragmentInDays(final Date date, final int fragment) {
         return getFragment(date, fragment, TimeUnit.DAYS);
     }
 
     /**
      * <p>Returns the number of milliseconds within the 
      * fragment. All datefields greater than the fragment will be ignored.</p> 
      * 
      * <p>Asking the milliseconds of any date will only return the number of milliseconds
      * of the current second (resulting in a number between 0 and 999). This 
      * method will retrieve the number of milliseconds for any fragment. 
      * For example, if you want to calculate the number of seconds past today, 
      * your fragment is Calendar.DATE or Calendar.DAY_OF_YEAR. The result will
      * be all seconds of the past hour(s), minutes(s) and second(s).</p> 
      * 
      * <p>Valid fragments are: Calendar.YEAR, Calendar.MONTH, both 
      * Calendar.DAY_OF_YEAR and Calendar.DATE, Calendar.HOUR_OF_DAY, 
      * Calendar.MINUTE, Calendar.SECOND and Calendar.MILLISECOND
      * A fragment less than or equal to a MILLISECOND field will return 0.</p> 
      * 
      * <ul>
      *  <li>January 1, 2008 7:15:10.538 with Calendar.SECOND as fragment will return 538
      *   (equivalent to calendar.get(Calendar.MILLISECOND))</li>
      *  <li>January 6, 2008 7:15:10.538 with Calendar.SECOND as fragment will return 538
      *   (equivalent to calendar.get(Calendar.MILLISECOND))</li>
      *  <li>January 6, 2008 7:15:10.538 with Calendar.MINUTE as fragment will return 10538
      *   (10*1000 + 538)</li>
      *  <li>January 16, 2008 7:15:10.538 with Calendar.MILLISECOND as fragment will return 0
      *   (a millisecond cannot be split in milliseconds)</li>
      * </ul>
      * 
      * @param calendar the calendar to work with, not null
      * @param fragment the {@code Calendar} field part of calendar to calculate 
      * @return number of milliseconds within the fragment of date
      * @throws IllegalArgumentException if the date is <code>null</code> or 
      * fragment is not supported
      * @since 2.4
      */
   public static long getFragmentInMilliseconds(final Calendar calendar, final int fragment) {
     return getFragment(calendar, fragment, TimeUnit.MILLISECONDS);
   }
     /**
      * <p>Returns the number of seconds within the 
      * fragment. All datefields greater than the fragment will be ignored.</p> 
      * 
      * <p>Asking the seconds of any date will only return the number of seconds
      * of the current minute (resulting in a number between 0 and 59). This 
      * method will retrieve the number of seconds for any fragment. 
      * For example, if you want to calculate the number of seconds past today, 
      * your fragment is Calendar.DATE or Calendar.DAY_OF_YEAR. The result will
      * be all seconds of the past hour(s) and minutes(s).</p> 
      * 
      * <p>Valid fragments are: Calendar.YEAR, Calendar.MONTH, both 
      * Calendar.DAY_OF_YEAR and Calendar.DATE, Calendar.HOUR_OF_DAY, 
      * Calendar.MINUTE, Calendar.SECOND and Calendar.MILLISECOND
      * A fragment less than or equal to a SECOND field will return 0.</p> 
      * 
      * <ul>
      *  <li>January 1, 2008 7:15:10.538 with Calendar.MINUTE as fragment will return 10
      *   (equivalent to calendar.get(Calendar.SECOND))</li>
      *  <li>January 6, 2008 7:15:10.538 with Calendar.MINUTE as fragment will return 10
      *   (equivalent to calendar.get(Calendar.SECOND))</li>
      *  <li>January 6, 2008 7:15:10.538 with Calendar.DAY_OF_YEAR as fragment will return 26110
      *   (7*3600 + 15*60 + 10)</li>
      *  <li>January 16, 2008 7:15:10.538 with Calendar.MILLISECOND as fragment will return 0
      *   (a millisecond cannot be split in seconds)</li>
      * </ul>
      * 
      * @param calendar the calendar to work with, not null
      * @param fragment the {@code Calendar} field part of calendar to calculate 
      * @return number of seconds within the fragment of date
      * @throws IllegalArgumentException if the date is <code>null</code> or 
      * fragment is not supported
      * @since 2.4
      */
     public static long getFragmentInSeconds(final Calendar calendar, final int fragment) {
         return getFragment(calendar, fragment, TimeUnit.SECONDS);
     }
     
     /**
      * <p>Returns the number of minutes within the 
      * fragment. All datefields greater than the fragment will be ignored.</p> 
      * 
      * <p>Asking the minutes of any date will only return the number of minutes
      * of the current hour (resulting in a number between 0 and 59). This 
      * method will retrieve the number of minutes for any fragment. 
      * For example, if you want to calculate the number of minutes past this month, 
      * your fragment is Calendar.MONTH. The result will be all minutes of the 
      * past day(s) and hour(s).</p> 
      * 
      * <p>Valid fragments are: Calendar.YEAR, Calendar.MONTH, both 
      * Calendar.DAY_OF_YEAR and Calendar.DATE, Calendar.HOUR_OF_DAY, 
      * Calendar.MINUTE, Calendar.SECOND and Calendar.MILLISECOND
      * A fragment less than or equal to a MINUTE field will return 0.</p> 
      * 
      * <ul>
      *  <li>January 1, 2008 7:15:10.538 with Calendar.HOUR_OF_DAY as fragment will return 15
      *   (equivalent to calendar.get(Calendar.MINUTES))</li>
      *  <li>January 6, 2008 7:15:10.538 with Calendar.HOUR_OF_DAY as fragment will return 15
      *   (equivalent to calendar.get(Calendar.MINUTES))</li>
      *  <li>January 1, 2008 7:15:10.538 with Calendar.MONTH as fragment will return 15</li>
      *  <li>January 6, 2008 7:15:10.538 with Calendar.MONTH as fragment will return 435 (7*60 + 15)</li>
      *  <li>January 16, 2008 7:15:10.538 with Calendar.MILLISECOND as fragment will return 0
      *   (a millisecond cannot be split in minutes)</li>
      * </ul>
      * 
      * @param calendar the calendar to work with, not null
      * @param fragment the {@code Calendar} field part of calendar to calculate 
      * @return number of minutes within the fragment of date
      * @throws IllegalArgumentException if the date is <code>null</code> or 
      * fragment is not supported
      * @since 2.4
      */
     public static long getFragmentInMinutes(final Calendar calendar, final int fragment) {
         return getFragment(calendar, fragment, TimeUnit.MINUTES);
     }
     
     /**
      * <p>Returns the number of hours within the 
      * fragment. All datefields greater than the fragment will be ignored.</p> 
      * 
      * <p>Asking the hours of any date will only return the number of hours
      * of the current day (resulting in a number between 0 and 23). This 
      * method will retrieve the number of hours for any fragment. 
      * For example, if you want to calculate the number of hours past this month, 
      * your fragment is Calendar.MONTH. The result will be all hours of the 
      * past day(s).</p> 
      * 
      * <p>Valid fragments are: Calendar.YEAR, Calendar.MONTH, both 
      * Calendar.DAY_OF_YEAR and Calendar.DATE, Calendar.HOUR_OF_DAY, 
      * Calendar.MINUTE, Calendar.SECOND and Calendar.MILLISECOND
      * A fragment less than or equal to a HOUR field will return 0.</p> 
      *  
      * <ul>
      *  <li>January 1, 2008 7:15:10.538 with Calendar.DAY_OF_YEAR as fragment will return 7
      *   (equivalent to calendar.get(Calendar.HOUR_OF_DAY))</li>
      *  <li>January 6, 2008 7:15:10.538 with Calendar.DAY_OF_YEAR as fragment will return 7
      *   (equivalent to calendar.get(Calendar.HOUR_OF_DAY))</li>
      *  <li>January 1, 2008 7:15:10.538 with Calendar.MONTH as fragment will return 7</li>
      *  <li>January 6, 2008 7:15:10.538 with Calendar.MONTH as fragment will return 127 (5*24 + 7)</li>
      *  <li>January 16, 2008 7:15:10.538 with Calendar.MILLISECOND as fragment will return 0
      *   (a millisecond cannot be split in hours)</li>
      * </ul>
      *  
      * @param calendar the calendar to work with, not null
      * @param fragment the {@code Calendar} field part of calendar to calculate 
      * @return number of hours within the fragment of date
      * @throws IllegalArgumentException if the date is <code>null</code> or 
      * fragment is not supported
      * @since 2.4
      */
     public static long getFragmentInHours(final Calendar calendar, final int fragment) {
         return getFragment(calendar, fragment, TimeUnit.HOURS);
     }
     
     /**
      * <p>Returns the number of days within the 
      * fragment. All datefields greater than the fragment will be ignored.</p> 
      * 
      * <p>Asking the days of any date will only return the number of days
      * of the current month (resulting in a number between 1 and 31). This 
      * method will retrieve the number of days for any fragment. 
      * For example, if you want to calculate the number of days past this year, 
      * your fragment is Calendar.YEAR. The result will be all days of the 
      * past month(s).</p> 
      * 
      * <p>Valid fragments are: Calendar.YEAR, Calendar.MONTH, both 
      * Calendar.DAY_OF_YEAR and Calendar.DATE, Calendar.HOUR_OF_DAY, 
      * Calendar.MINUTE, Calendar.SECOND and Calendar.MILLISECOND
      * A fragment less than or equal to a DAY field will return 0.</p> 
      * 
      * <ul>
      *  <li>January 28, 2008 with Calendar.MONTH as fragment will return 28
      *   (equivalent to calendar.get(Calendar.DAY_OF_MONTH))</li>
      *  <li>February 28, 2008 with Calendar.MONTH as fragment will return 28
      *   (equivalent to calendar.get(Calendar.DAY_OF_MONTH))</li>
      *  <li>January 28, 2008 with Calendar.YEAR as fragment will return 28
      *   (equivalent to calendar.get(Calendar.DAY_OF_YEAR))</li>
      *  <li>February 28, 2008 with Calendar.YEAR as fragment will return 59
      *   (equivalent to calendar.get(Calendar.DAY_OF_YEAR))</li>
      *  <li>January 28, 2008 with Calendar.MILLISECOND as fragment will return 0
      *   (a millisecond cannot be split in days)</li>
      * </ul>
      * 
      * @param calendar the calendar to work with, not null
      * @param fragment the {@code Calendar} field part of calendar to calculate 
      * @return number of days within the fragment of date
      * @throws IllegalArgumentException if the date is <code>null</code> or 
      * fragment is not supported
      * @since 2.4
      */
     public static long getFragmentInDays(final Calendar calendar, final int fragment) {
         return getFragment(calendar, fragment, TimeUnit.DAYS);
     }
     
     /**
      * Gets a Date fragment for any unit.
      * 
      * @param date the date to work with, not null
      * @param fragment the Calendar field part of date to calculate 
      * @param unit the time unit
      * @return number of units within the fragment of the date
      * @throws IllegalArgumentException if the date is <code>null</code> or 
      * fragment is not supported
      * @since 2.4
      */
     private static long getFragment(final Date date, final int fragment, final TimeUnit unit) {
         if(date == null) {
             throw  new IllegalArgumentException("The date must not be null");
         }
         final Calendar calendar = Calendar.getInstance();
         calendar.setTime(date);
         return getFragment(calendar, fragment, unit);
     }
 
     /**
      * Gets a Calendar fragment for any unit.
      * 
      * @param calendar the calendar to work with, not null
      * @param fragment the Calendar field part of calendar to calculate 
      * @param unit the time unit
      * @return number of units within the fragment of the calendar
      * @throws IllegalArgumentException if the date is <code>null</code> or 
      * fragment is not supported
      * @since 2.4
      */
     private static long getFragment(final Calendar calendar, final int fragment, final TimeUnit unit) {
         if(calendar == null) {
             throw  new IllegalArgumentException("The date must not be null"); 
         }
 
         long result = 0;
         
         final int offset = (unit == TimeUnit.DAYS) ? 0 : 1;
         
         // Fragments bigger than a day require a breakdown to days
         switch (fragment) {
             case Calendar.YEAR:
                 result += unit.convert(calendar.get(Calendar.DAY_OF_YEAR) - offset, TimeUnit.DAYS);
                 break;
             case Calendar.MONTH:
                 result += unit.convert(calendar.get(Calendar.DAY_OF_MONTH) - offset, TimeUnit.DAYS);
                 break;
             default:
                 break;
         }
 
         switch (fragment) {
             // Number of days already calculated for these cases
             case Calendar.YEAR:
             case Calendar.MONTH:
             
             // The rest of the valid cases
             case Calendar.DAY_OF_YEAR:
             case Calendar.DATE:
                 result += unit.convert(calendar.get(Calendar.HOUR_OF_DAY), TimeUnit.HOURS);
                 //$FALL-THROUGH$
             case Calendar.HOUR_OF_DAY:
                 result += unit.convert(calendar.get(Calendar.MINUTE), TimeUnit.MINUTES);
                 //$FALL-THROUGH$
             case Calendar.MINUTE:
                 result += unit.convert(calendar.get(Calendar.SECOND), TimeUnit.SECONDS);
                 //$FALL-THROUGH$
             case Calendar.SECOND:
                 result += unit.convert(calendar.get(Calendar.MILLISECOND), TimeUnit.MILLISECONDS);
                 break;
             case Calendar.MILLISECOND: break;//never useful
                 default: throw new IllegalArgumentException("The fragment " + fragment + " is not supported");
         }
         return result;
     }
     
     /**
      * Determines if two calendars are equal up to no more than the specified 
      * most significant field.
      * 
      * @param cal1 the first calendar, not <code>null</code>
      * @param cal2 the second calendar, not <code>null</code>
      * @param field the field from {@code Calendar}
      * @return <code>true</code> if equal; otherwise <code>false</code>
      * @throws IllegalArgumentException if any argument is <code>null</code>
      * @see #truncate(Calendar, int)
      * @see #truncatedEquals(Date, Date, int)
      * @since 3.0
      */
     public static boolean truncatedEquals(final Calendar cal1, final Calendar cal2, final int field) {
         return truncatedCompareTo(cal1, cal2, field) == 0;
     }
 
     /**
      * Determines if two dates are equal up to no more than the specified 
      * most significant field.
      * 
      * @param date1 the first date, not <code>null</code>
      * @param date2 the second date, not <code>null</code>
      * @param field the field from {@code Calendar}
      * @return <code>true</code> if equal; otherwise <code>false</code>
      * @throws IllegalArgumentException if any argument is <code>null</code>
      * @see #truncate(Date, int)
      * @see #truncatedEquals(Calendar, Calendar, int)
      * @since 3.0
      */
     public static boolean truncatedEquals(final Date date1, final Date date2, final int field) {
         return truncatedCompareTo(date1, date2, field) == 0;
     }
 
     /**
      * Determines how two calendars compare up to no more than the specified 
      * most significant field.
      * 
      * @param cal1 the first calendar, not <code>null</code>
      * @param cal2 the second calendar, not <code>null</code>
      * @param field the field from {@code Calendar}
      * @return a negative integer, zero, or a positive integer as the first 
      * calendar is less than, equal to, or greater than the second.
      * @throws IllegalArgumentException if any argument is <code>null</code>
      * @see #truncate(Calendar, int)
      * @see #truncatedCompareTo(Date, Date, int)
      * @since 3.0
      */
     public static int truncatedCompareTo(final Calendar cal1, final Calendar cal2, final int field) {
         final Calendar truncatedCal1 = truncate(cal1, field);
         final Calendar truncatedCal2 = truncate(cal2, field);
         return truncatedCal1.compareTo(truncatedCal2);
     }
 
     /**
      * Determines how two dates compare up to no more than the specified 
      * most significant field.
      * 
      * @param date1 the first date, not <code>null</code>
      * @param date2 the second date, not <code>null</code>
      * @param field the field from <code>Calendar</code>
      * @return a negative integer, zero, or a positive integer as the first 
      * date is less than, equal to, or greater than the second.
      * @throws IllegalArgumentException if any argument is <code>null</code>
      * @see #truncate(Calendar, int)
      * @see #truncatedCompareTo(Date, Date, int)
      * @since 3.0
      */
     public static int truncatedCompareTo(final Date date1, final Date date2, final int field) {
         final Date truncatedDate1 = truncate(date1, field);
         final Date truncatedDate2 = truncate(date2, field);
         return truncatedDate1.compareTo(truncatedDate2);
     }
 
 
     //-----------------------------------------------------------------------
     /**
      * <p>Date iterator.</p>
      */
     static class DateIterator implements Iterator<Calendar> {
         private final Calendar endFinal;
         private final Calendar spot;
         
         /**
          * Constructs a DateIterator that ranges from one date to another. 
          *
          * @param startFinal start date (inclusive)
          * @param endFinal end date (inclusive)
          */
         DateIterator(final Calendar startFinal, final Calendar endFinal) {
             super();
             this.endFinal = endFinal;
             spot = startFinal;
             spot.add(Calendar.DATE, -1);
         }
 
         /**
          * Has the iterator not reached the end date yet?
          *
          * @return <code>true</code> if the iterator has yet to reach the end date
          */
         @Override
         public boolean hasNext() {
             return spot.before(endFinal);
         }
 
         /**
          * Return the next calendar in the iteration
          *
          * @return Object calendar for the next date
          */
         @Override
         public Calendar next() {
             if (spot.equals(endFinal)) {
                 throw new NoSuchElementException();
             }
             spot.add(Calendar.DATE, 1);
             return (Calendar) spot.clone();
         }
 
         /**
          * Always throws UnsupportedOperationException.
          * 
          * @throws UnsupportedOperationException
          * @see java.util.Iterator#remove()
          */
         @Override
         public void remove() {
             throw new UnsupportedOperationException();
         }
     }
 
 }