Java example source code file (TemporalAdjusters.java)
The TemporalAdjusters.java Java example source code/*
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* Copyright (c) 2012-2013, Stephen Colebourne & Michael Nascimento Santos
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package java.time.temporal;
import static java.time.temporal.ChronoField.DAY_OF_MONTH;
import static java.time.temporal.ChronoField.DAY_OF_WEEK;
import static java.time.temporal.ChronoField.DAY_OF_YEAR;
import static java.time.temporal.ChronoUnit.DAYS;
import static java.time.temporal.ChronoUnit.MONTHS;
import static java.time.temporal.ChronoUnit.YEARS;
import java.time.DayOfWeek;
import java.time.LocalDate;
import java.util.Objects;
import java.util.function.UnaryOperator;
/**
* Common and useful TemporalAdjusters.
* <p>
* 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.
* <p>
* 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)}:
* <pre>
* // these two lines are equivalent, but the second approach is recommended
* temporal = thisAdjuster.adjustInto(temporal);
* temporal = temporal.with(thisAdjuster);
* </pre>
* It is recommended to use the second approach, {@code with(TemporalAdjuster)},
* as it is a lot clearer to read in code.
* <p>
* This class contains a standard set of adjusters, available as static methods.
* These include:
* <ul>
* <li>finding the first or last day of the month
* <li>finding the first day of next month
* <li>finding the first or last day of the year
* <li>finding the first day of next year
* <li>finding the first or last day-of-week within a month, such as "first Wednesday in June"
* <li>finding the next or previous day-of-week, such as "next Thursday"
* </ul>
*
* @implSpec
* All the implementations supplied by the static methods are immutable.
*
* @see TemporalAdjuster
* @since 1.8
*/
public final class TemporalAdjusters {
/**
* Private constructor since this is a utility class.
*/
private TemporalAdjusters() {
}
//-----------------------------------------------------------------------
/**
* Obtains a {@code TemporalAdjuster} that wraps a date adjuster.
* <p>
* 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.
* <p>
* In general, user-written adjusters should be static constants:
* <pre>{@code
* static TemporalAdjuster TWO_DAYS_LATER =
* TemporalAdjusters.ofDateAdjuster(date -> date.plusDays(2));
* }</pre>
*
* @param dateBasedAdjuster the date-based adjuster, not null
* @return the temporal adjuster wrapping on the date adjuster, not null
*/
public static TemporalAdjuster ofDateAdjuster(UnaryOperator<LocalDate> dateBasedAdjuster) {
Objects.requireNonNull(dateBasedAdjuster, "dateBasedAdjuster");
return (temporal) -> {
LocalDate input = LocalDate.from(temporal);
LocalDate output = dateBasedAdjuster.apply(input);
return temporal.with(output);
};
}
//-----------------------------------------------------------------------
/**
* Returns the "first day of month" adjuster, which returns a new date set to
* the first day of the current month.
* <p>
* The ISO calendar system behaves as follows:<br>
* The input 2011-01-15 will return 2011-01-01.<br>
* The input 2011-02-15 will return 2011-02-01.
* <p>
* The behavior is suitable for use with most calendar systems.
* It is equivalent to:
* <pre>
* temporal.with(DAY_OF_MONTH, 1);
* </pre>
*
* @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.
* <p>
* The ISO calendar system behaves as follows:<br>
* The input 2011-01-15 will return 2011-01-31.<br>
* The input 2011-02-15 will return 2011-02-28.<br>
* The input 2012-02-15 will return 2012-02-29 (leap year).<br>
* The input 2011-04-15 will return 2011-04-30.
* <p>
* The behavior is suitable for use with most calendar systems.
* It is equivalent to:
* <pre>
* long lastDay = temporal.range(DAY_OF_MONTH).getMaximum();
* temporal.with(DAY_OF_MONTH, lastDay);
* </pre>
*
* @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.
* <p>
* The ISO calendar system behaves as follows:<br>
* The input 2011-01-15 will return 2011-02-01.<br>
* The input 2011-02-15 will return 2011-03-01.
* <p>
* The behavior is suitable for use with most calendar systems.
* It is equivalent to:
* <pre>
* temporal.with(DAY_OF_MONTH, 1).plus(1, MONTHS);
* </pre>
*
* @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.
* <p>
* The ISO calendar system behaves as follows:<br>
* The input 2011-01-15 will return 2011-01-01.<br>
* The input 2011-02-15 will return 2011-01-01.<br>
* <p>
* The behavior is suitable for use with most calendar systems.
* It is equivalent to:
* <pre>
* temporal.with(DAY_OF_YEAR, 1);
* </pre>
*
* @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.
* <p>
* The ISO calendar system behaves as follows:<br>
* The input 2011-01-15 will return 2011-12-31.<br>
* The input 2011-02-15 will return 2011-12-31.<br>
* <p>
* The behavior is suitable for use with most calendar systems.
* It is equivalent to:
* <pre>
* long lastDay = temporal.range(DAY_OF_YEAR).getMaximum();
* temporal.with(DAY_OF_YEAR, lastDay);
* </pre>
*
* @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.
* <p>
* The ISO calendar system behaves as follows:<br>
* The input 2011-01-15 will return 2012-01-01.
* <p>
* The behavior is suitable for use with most calendar systems.
* It is equivalent to:
* <pre>
* temporal.with(DAY_OF_YEAR, 1).plus(1, YEARS);
* </pre>
*
* @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'.
* <p>
* The ISO calendar system behaves as follows:<br>
* The input 2011-12-15 for (MONDAY) will return 2011-12-05.<br>
* The input 2011-12-15 for (FRIDAY) will return 2011-12-02.<br>
* <p>
* 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'.
* <p>
* The ISO calendar system behaves as follows:<br>
* The input 2011-12-15 for (MONDAY) will return 2011-12-26.<br>
* The input 2011-12-15 for (FRIDAY) will return 2011-12-30.<br>
* <p>
* 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'.
* <p>
* The ISO calendar system behaves as follows:<br>
* The input 2011-12-15 for (1,TUESDAY) will return 2011-12-06.<br>
* The input 2011-12-15 for (2,TUESDAY) will return 2011-12-13.<br>
* The input 2011-12-15 for (3,TUESDAY) will return 2011-12-20.<br>
* The input 2011-12-15 for (4,TUESDAY) will return 2011-12-27.<br>
* The input 2011-12-15 for (5,TUESDAY) will return 2012-01-03.<br>
* The input 2011-12-15 for (-1,TUESDAY) will return 2011-12-27 (last in month).<br>
* The input 2011-12-15 for (-4,TUESDAY) will return 2011-12-06 (3 weeks before last in month).<br>
* The input 2011-12-15 for (-5,TUESDAY) will return 2011-11-29 (4 weeks before last in month).<br>
* The input 2011-12-15 for (0,TUESDAY) will return 2011-11-29 (last in previous month).<br>
* <p>
* 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.
* <p>
* 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.
* <p>
* The ISO calendar system behaves as follows:<br>
* The input 2011-01-15 (a Saturday) for parameter (MONDAY) will return 2011-01-17 (two days later).<br>
* The input 2011-01-15 (a Saturday) for parameter (WEDNESDAY) will return 2011-01-19 (four days later).<br>
* The input 2011-01-15 (a Saturday) for parameter (SATURDAY) will return 2011-01-22 (seven days later).
* <p>
* 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.
* <p>
* The ISO calendar system behaves as follows:<br>
* The input 2011-01-15 (a Saturday) for parameter (MONDAY) will return 2011-01-17 (two days later).<br>
* The input 2011-01-15 (a Saturday) for parameter (WEDNESDAY) will return 2011-01-19 (four days later).<br>
* The input 2011-01-15 (a Saturday) for parameter (SATURDAY) will return 2011-01-15 (same as input).
* <p>
* 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.
* <p>
* The ISO calendar system behaves as follows:<br>
* The input 2011-01-15 (a Saturday) for parameter (MONDAY) will return 2011-01-10 (five days earlier).<br>
* The input 2011-01-15 (a Saturday) for parameter (WEDNESDAY) will return 2011-01-12 (three days earlier).<br>
* The input 2011-01-15 (a Saturday) for parameter (SATURDAY) will return 2011-01-08 (seven days earlier).
* <p>
* 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.
* <p>
* The ISO calendar system behaves as follows:<br>
* The input 2011-01-15 (a Saturday) for parameter (MONDAY) will return 2011-01-10 (five days earlier).<br>
* The input 2011-01-15 (a Saturday) for parameter (WEDNESDAY) will return 2011-01-12 (three days earlier).<br>
* The input 2011-01-15 (a Saturday) for parameter (SATURDAY) will return 2011-01-15 (same as input).
* <p>
* 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);
};
}
}
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