* Adjusters are a key tool for modifying temporal objects. * They exist to externalize the process of adjustment, permitting different * approaches, as per the strategy design pattern. * Examples might be an adjuster that sets the date avoiding weekends, or one that * sets the date to the last day of the month. *
* There are two equivalent ways of using a {@code TemporalAdjuster}. * The first is to invoke the method on the interface directly. * The second is to use {@link Temporal#with(TemporalAdjuster)}: *
* // these two lines are equivalent, but the second approach is recommended * temporal = thisAdjuster.adjustInto(temporal); * temporal = temporal.with(thisAdjuster); ** It is recommended to use the second approach, {@code with(TemporalAdjuster)}, * as it is a lot clearer to read in code. *
* This class contains a standard set of adjusters, available as static methods. * These include: *
* The {@code TemporalAdjuster} is based on the low level {@code Temporal} interface. * This method allows an adjustment from {@code LocalDate} to {@code LocalDate} * to be wrapped to match the temporal-based interface. * This is provided for convenience to make user-written adjusters simpler. *
* In general, user-written adjusters should be static constants: *
{@code
* static TemporalAdjuster TWO_DAYS_LATER =
* TemporalAdjusters.ofDateAdjuster(date -> date.plusDays(2));
* }
*
* @param dateBasedAdjuster the date-based adjuster, not null
* @return the temporal adjuster wrapping on the date adjuster, not null
*/
public static TemporalAdjuster ofDateAdjuster(UnaryOperator
* The ISO calendar system behaves as follows:
* The input 2011-01-15 will return 2011-01-01.
* The input 2011-02-15 will return 2011-02-01.
*
* The behavior is suitable for use with most calendar systems. * It is equivalent to: *
* temporal.with(DAY_OF_MONTH, 1);
*
*
* @return the first day-of-month adjuster, not null
*/
public static TemporalAdjuster firstDayOfMonth() {
return (temporal) -> temporal.with(DAY_OF_MONTH, 1);
}
/**
* Returns the "last day of month" adjuster, which returns a new date set to
* the last day of the current month.
*
* The ISO calendar system behaves as follows:
* The input 2011-01-15 will return 2011-01-31.
* The input 2011-02-15 will return 2011-02-28.
* The input 2012-02-15 will return 2012-02-29 (leap year).
* The input 2011-04-15 will return 2011-04-30.
*
* The behavior is suitable for use with most calendar systems. * It is equivalent to: *
* long lastDay = temporal.range(DAY_OF_MONTH).getMaximum();
* temporal.with(DAY_OF_MONTH, lastDay);
*
*
* @return the last day-of-month adjuster, not null
*/
public static TemporalAdjuster lastDayOfMonth() {
return (temporal) -> temporal.with(DAY_OF_MONTH, temporal.range(DAY_OF_MONTH).getMaximum());
}
/**
* Returns the "first day of next month" adjuster, which returns a new date set to
* the first day of the next month.
*
* The ISO calendar system behaves as follows:
* The input 2011-01-15 will return 2011-02-01.
* The input 2011-02-15 will return 2011-03-01.
*
* The behavior is suitable for use with most calendar systems. * It is equivalent to: *
* temporal.with(DAY_OF_MONTH, 1).plus(1, MONTHS);
*
*
* @return the first day of next month adjuster, not null
*/
public static TemporalAdjuster firstDayOfNextMonth() {
return (temporal) -> temporal.with(DAY_OF_MONTH, 1).plus(1, MONTHS);
}
//-----------------------------------------------------------------------
/**
* Returns the "first day of year" adjuster, which returns a new date set to
* the first day of the current year.
*
* The ISO calendar system behaves as follows:
* The input 2011-01-15 will return 2011-01-01.
* The input 2011-02-15 will return 2011-01-01.
*
* The behavior is suitable for use with most calendar systems. * It is equivalent to: *
* temporal.with(DAY_OF_YEAR, 1);
*
*
* @return the first day-of-year adjuster, not null
*/
public static TemporalAdjuster firstDayOfYear() {
return (temporal) -> temporal.with(DAY_OF_YEAR, 1);
}
/**
* Returns the "last day of year" adjuster, which returns a new date set to
* the last day of the current year.
*
* The ISO calendar system behaves as follows:
* The input 2011-01-15 will return 2011-12-31.
* The input 2011-02-15 will return 2011-12-31.
*
* The behavior is suitable for use with most calendar systems. * It is equivalent to: *
* long lastDay = temporal.range(DAY_OF_YEAR).getMaximum();
* temporal.with(DAY_OF_YEAR, lastDay);
*
*
* @return the last day-of-year adjuster, not null
*/
public static TemporalAdjuster lastDayOfYear() {
return (temporal) -> temporal.with(DAY_OF_YEAR, temporal.range(DAY_OF_YEAR).getMaximum());
}
/**
* Returns the "first day of next year" adjuster, which returns a new date set to
* the first day of the next year.
*
* The ISO calendar system behaves as follows:
* The input 2011-01-15 will return 2012-01-01.
*
* The behavior is suitable for use with most calendar systems. * It is equivalent to: *
* temporal.with(DAY_OF_YEAR, 1).plus(1, YEARS);
*
*
* @return the first day of next month adjuster, not null
*/
public static TemporalAdjuster firstDayOfNextYear() {
return (temporal) -> temporal.with(DAY_OF_YEAR, 1).plus(1, YEARS);
}
//-----------------------------------------------------------------------
/**
* Returns the first in month adjuster, which returns a new date
* in the same month with the first matching day-of-week.
* This is used for expressions like 'first Tuesday in March'.
*
* The ISO calendar system behaves as follows:
* The input 2011-12-15 for (MONDAY) will return 2011-12-05.
* The input 2011-12-15 for (FRIDAY) will return 2011-12-02.
*
* The behavior is suitable for use with most calendar systems. * It uses the {@code DAY_OF_WEEK} and {@code DAY_OF_MONTH} fields * and the {@code DAYS} unit, and assumes a seven day week. * * @param dayOfWeek the day-of-week, not null * @return the first in month adjuster, not null */ public static TemporalAdjuster firstInMonth(DayOfWeek dayOfWeek) { return TemporalAdjusters.dayOfWeekInMonth(1, dayOfWeek); } /** * Returns the last in month adjuster, which returns a new date * in the same month with the last matching day-of-week. * This is used for expressions like 'last Tuesday in March'. *
* The ISO calendar system behaves as follows:
* The input 2011-12-15 for (MONDAY) will return 2011-12-26.
* The input 2011-12-15 for (FRIDAY) will return 2011-12-30.
*
* The behavior is suitable for use with most calendar systems. * It uses the {@code DAY_OF_WEEK} and {@code DAY_OF_MONTH} fields * and the {@code DAYS} unit, and assumes a seven day week. * * @param dayOfWeek the day-of-week, not null * @return the first in month adjuster, not null */ public static TemporalAdjuster lastInMonth(DayOfWeek dayOfWeek) { return TemporalAdjusters.dayOfWeekInMonth(-1, dayOfWeek); } /** * Returns the day-of-week in month adjuster, which returns a new date * in the same month with the ordinal day-of-week. * This is used for expressions like the 'second Tuesday in March'. *
* The ISO calendar system behaves as follows:
* The input 2011-12-15 for (1,TUESDAY) will return 2011-12-06.
* The input 2011-12-15 for (2,TUESDAY) will return 2011-12-13.
* The input 2011-12-15 for (3,TUESDAY) will return 2011-12-20.
* The input 2011-12-15 for (4,TUESDAY) will return 2011-12-27.
* The input 2011-12-15 for (5,TUESDAY) will return 2012-01-03.
* The input 2011-12-15 for (-1,TUESDAY) will return 2011-12-27 (last in month).
* The input 2011-12-15 for (-4,TUESDAY) will return 2011-12-06 (3 weeks before last in month).
* The input 2011-12-15 for (-5,TUESDAY) will return 2011-11-29 (4 weeks before last in month).
* The input 2011-12-15 for (0,TUESDAY) will return 2011-11-29 (last in previous month).
*
* For a positive or zero ordinal, the algorithm is equivalent to finding the first * day-of-week that matches within the month and then adding a number of weeks to it. * For a negative ordinal, the algorithm is equivalent to finding the last * day-of-week that matches within the month and then subtracting a number of weeks to it. * The ordinal number of weeks is not validated and is interpreted leniently * according to this algorithm. This definition means that an ordinal of zero finds * the last matching day-of-week in the previous month. *
* The behavior is suitable for use with most calendar systems. * It uses the {@code DAY_OF_WEEK} and {@code DAY_OF_MONTH} fields * and the {@code DAYS} unit, and assumes a seven day week. * * @param ordinal the week within the month, unbounded but typically from -5 to 5 * @param dayOfWeek the day-of-week, not null * @return the day-of-week in month adjuster, not null */ public static TemporalAdjuster dayOfWeekInMonth(int ordinal, DayOfWeek dayOfWeek) { Objects.requireNonNull(dayOfWeek, "dayOfWeek"); int dowValue = dayOfWeek.getValue(); if (ordinal >= 0) { return (temporal) -> { Temporal temp = temporal.with(DAY_OF_MONTH, 1); int curDow = temp.get(DAY_OF_WEEK); int dowDiff = (dowValue - curDow + 7) % 7; dowDiff += (ordinal - 1L) * 7L; // safe from overflow return temp.plus(dowDiff, DAYS); }; } else { return (temporal) -> { Temporal temp = temporal.with(DAY_OF_MONTH, temporal.range(DAY_OF_MONTH).getMaximum()); int curDow = temp.get(DAY_OF_WEEK); int daysDiff = dowValue - curDow; daysDiff = (daysDiff == 0 ? 0 : (daysDiff > 0 ? daysDiff - 7 : daysDiff)); daysDiff -= (-ordinal - 1L) * 7L; // safe from overflow return temp.plus(daysDiff, DAYS); }; } } //----------------------------------------------------------------------- /** * Returns the next day-of-week adjuster, which adjusts the date to the * first occurrence of the specified day-of-week after the date being adjusted. *
* The ISO calendar system behaves as follows:
* The input 2011-01-15 (a Saturday) for parameter (MONDAY) will return 2011-01-17 (two days later).
* The input 2011-01-15 (a Saturday) for parameter (WEDNESDAY) will return 2011-01-19 (four days later).
* The input 2011-01-15 (a Saturday) for parameter (SATURDAY) will return 2011-01-22 (seven days later).
*
* The behavior is suitable for use with most calendar systems. * It uses the {@code DAY_OF_WEEK} field and the {@code DAYS} unit, * and assumes a seven day week. * * @param dayOfWeek the day-of-week to move the date to, not null * @return the next day-of-week adjuster, not null */ public static TemporalAdjuster next(DayOfWeek dayOfWeek) { int dowValue = dayOfWeek.getValue(); return (temporal) -> { int calDow = temporal.get(DAY_OF_WEEK); int daysDiff = calDow - dowValue; return temporal.plus(daysDiff >= 0 ? 7 - daysDiff : -daysDiff, DAYS); }; } /** * Returns the next-or-same day-of-week adjuster, which adjusts the date to the * first occurrence of the specified day-of-week after the date being adjusted * unless it is already on that day in which case the same object is returned. *
* The ISO calendar system behaves as follows:
* The input 2011-01-15 (a Saturday) for parameter (MONDAY) will return 2011-01-17 (two days later).
* The input 2011-01-15 (a Saturday) for parameter (WEDNESDAY) will return 2011-01-19 (four days later).
* The input 2011-01-15 (a Saturday) for parameter (SATURDAY) will return 2011-01-15 (same as input).
*
* The behavior is suitable for use with most calendar systems. * It uses the {@code DAY_OF_WEEK} field and the {@code DAYS} unit, * and assumes a seven day week. * * @param dayOfWeek the day-of-week to check for or move the date to, not null * @return the next-or-same day-of-week adjuster, not null */ public static TemporalAdjuster nextOrSame(DayOfWeek dayOfWeek) { int dowValue = dayOfWeek.getValue(); return (temporal) -> { int calDow = temporal.get(DAY_OF_WEEK); if (calDow == dowValue) { return temporal; } int daysDiff = calDow - dowValue; return temporal.plus(daysDiff >= 0 ? 7 - daysDiff : -daysDiff, DAYS); }; } /** * Returns the previous day-of-week adjuster, which adjusts the date to the * first occurrence of the specified day-of-week before the date being adjusted. *
* The ISO calendar system behaves as follows:
* The input 2011-01-15 (a Saturday) for parameter (MONDAY) will return 2011-01-10 (five days earlier).
* The input 2011-01-15 (a Saturday) for parameter (WEDNESDAY) will return 2011-01-12 (three days earlier).
* The input 2011-01-15 (a Saturday) for parameter (SATURDAY) will return 2011-01-08 (seven days earlier).
*
* The behavior is suitable for use with most calendar systems. * It uses the {@code DAY_OF_WEEK} field and the {@code DAYS} unit, * and assumes a seven day week. * * @param dayOfWeek the day-of-week to move the date to, not null * @return the previous day-of-week adjuster, not null */ public static TemporalAdjuster previous(DayOfWeek dayOfWeek) { int dowValue = dayOfWeek.getValue(); return (temporal) -> { int calDow = temporal.get(DAY_OF_WEEK); int daysDiff = dowValue - calDow; return temporal.minus(daysDiff >= 0 ? 7 - daysDiff : -daysDiff, DAYS); }; } /** * Returns the previous-or-same day-of-week adjuster, which adjusts the date to the * first occurrence of the specified day-of-week before the date being adjusted * unless it is already on that day in which case the same object is returned. *
* The ISO calendar system behaves as follows:
* The input 2011-01-15 (a Saturday) for parameter (MONDAY) will return 2011-01-10 (five days earlier).
* The input 2011-01-15 (a Saturday) for parameter (WEDNESDAY) will return 2011-01-12 (three days earlier).
* The input 2011-01-15 (a Saturday) for parameter (SATURDAY) will return 2011-01-15 (same as input).
*
* The behavior is suitable for use with most calendar systems. * It uses the {@code DAY_OF_WEEK} field and the {@code DAYS} unit, * and assumes a seven day week. * * @param dayOfWeek the day-of-week to check for or move the date to, not null * @return the previous-or-same day-of-week adjuster, not null */ public static TemporalAdjuster previousOrSame(DayOfWeek dayOfWeek) { int dowValue = dayOfWeek.getValue(); return (temporal) -> { int calDow = temporal.get(DAY_OF_WEEK); if (calDow == dowValue) { return temporal; } int daysDiff = dowValue - calDow; return temporal.minus(daysDiff >= 0 ? 7 - daysDiff : -daysDiff, DAYS); }; } }