java8-datetime-temporaladjusters

Reference: https://docs.oracle.com/javase/8/docs/api/java/time/temporal/TemporalAdjusters.html

preview

TemporalAdjuster dayOfWeekInMonth(int ordinal, DayOfWeek dayOfWeek) - Returns the day-of-week in month adjuster, which returns a new date in the same month with the ordinal day-of-week.

var firstMondayInMonth = TemporalAdjusters.dayOfWeekInMonth(1, DayOfWeek.MONDAY);
var secondTuesdayInMonth = TemporalAdjusters.dayOfWeekInMonth(2, DayOfWeek.TUESDAY);

assertThat(LocalDate.parse("2019-01-12").with(firstMondayInMonth), 
        is(LocalDate.parse("2019-01-07")));
assertThat(LocalDate.parse("2019-01-12").with(secondTuesdayInMonth), 
        is(LocalDate.parse("2019-01-08")));

TemporalAdjuster firstDayOfMonth() - Returns the "first day of month" adjuster, which returns a new date set to the first day of the current month.

assertThat(LocalDate.parse("2019-01-12").with(TemporalAdjusters.firstDayOfMonth()), 
        is(LocalDate.parse("2019-01-01")));

assertThat(LocalDate.parse("2019-02-22").with(TemporalAdjusters.firstDayOfMonth()),
        is(LocalDate.parse("2019-02-01")));

TemporalAdjuster firstDayOfNextMonth() - Returns the "first day of next month" adjuster, which returns a new date set to the first day of the next month.

assertThat(LocalDate.parse("2019-01-12").with(TemporalAdjusters.firstDayOfNextMonth()),
        is(LocalDate.parse("2019-02-01")));

assertThat(LocalDate.parse("2019-02-22").with(TemporalAdjusters.firstDayOfNextMonth()),
        is(LocalDate.parse("2019-03-01")));

TemporalAdjuster firstDayOfNextYear() - Returns the "first day of next year" adjuster, which returns a new date set to the first day of the next year.
```
assertThat(LocalDate.parse("2019-01-12").with(TemporalAdjusters.firstDayOfNextYear()),
        is(LocalDate.parse("2020-01-01")));
```
TemporalAdjuster firstDayOfYear() - Returns the "first day of year" adjuster, which returns a new date set to the first day of the current year.
```
assertThat(LocalDate.parse("2019-01-12").with(TemporalAdjusters.firstDayOfYear()),
        is(LocalDate.parse("2019-01-01")));
```
TemporalAdjuster firstInMonth(DayOfWeek dayOfWeek) - Returns the first in month adjuster, which returns a new date in the same month with the first matching day-of-week.
```
assertThat(LocalDate.parse("2019-01-01").with(TemporalAdjusters.firstInMonth(DayOfWeek.SATURDAY)),
        is(LocalDate.parse("2019-01-05")));
```
TemporalAdjuster lastDayOfMonth() - Returns the "last day of month" adjuster, which returns a new date set to the last day of the current month.
```
assertThat(LocalDate.parse("2019-01-01").with(TemporalAdjusters.lastDayOfMonth()),
        is(LocalDate.parse("2019-01-31")));
```
TemporalAdjuster lastDayOfYear() - Returns the "last day of year" adjuster, which returns a new date set to the last day of the current year.
```
assertThat(LocalDate.parse("2019-01-01").with(TemporalAdjusters.lastDayOfYear()),
        is(LocalDate.parse("2019-12-31")));
```
TemporalAdjuster lastInMonth(DayOfWeek dayOfWeek) - Returns the last in month adjuster, which returns a new date in the same month with the last matching day-of-week.
```
assertThat(LocalDate.parse("2019-01-01").with(TemporalAdjusters.lastInMonth(DayOfWeek.FRIDAY)),
        is(LocalDate.parse("2019-01-25")));
```

TemporalAdjuster next(DayOfWeek dayOfWeek) - 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.

assertThat(LocalDate.parse("2019-01-03").with(TemporalAdjusters.next(DayOfWeek.FRIDAY)),
        is(LocalDate.parse("2019-01-04")));

assertThat(LocalDate.parse("2019-01-04").with(TemporalAdjusters.next(DayOfWeek.FRIDAY)),
        is(LocalDate.parse("2019-01-11")));

TemporalAdjuster nextOrSame(DayOfWeek dayOfWeek) - 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.

assertThat(LocalDate.parse("2019-01-03").with(TemporalAdjusters.nextOrSame(DayOfWeek.FRIDAY)),
        is(LocalDate.parse("2019-01-04")));

assertThat(LocalDate.parse("2019-01-04").with(TemporalAdjusters.nextOrSame(DayOfWeek.FRIDAY)),
        is(LocalDate.parse("2019-01-04")));

TemporalAdjuster ofDateAdjuster(UnaryOperator<LocalDate> dateBasedAdjuster) - Obtains a TemporalAdjuster that wraps a date adjuster.

assertThat(LocalDate.parse("2019-01-01").with(TemporalAdjusters.ofDateAdjuster(date -> date.plusWeeks(4))),
        is(LocalDate.parse("2019-01-29")));

TemporalAdjuster previous(DayOfWeek dayOfWeek) - 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.

assertThat(LocalDate.parse("2019-01-04").with(TemporalAdjusters.previous(DayOfWeek.FRIDAY)),
        is(LocalDate.parse("2018-12-28")));

assertThat(LocalDate.parse("2019-01-11").with(TemporalAdjusters.previous(DayOfWeek.FRIDAY)),
        is(LocalDate.parse("2019-01-04")));

TemporalAdjuster previousOrSame(DayOfWeek dayOfWeek) - 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.

assertThat(LocalDate.parse("2019-01-05").with(TemporalAdjusters.previousOrSame(DayOfWeek.FRIDAY)),
        is(LocalDate.parse("2019-01-04")));

assertThat(LocalDate.parse("2019-01-04").with(TemporalAdjusters.previousOrSame(DayOfWeek.FRIDAY)),
        is(LocalDate.parse("2019-01-04")));

project description

We will show how to implement custom adjusters (CustomAdjusters):

find the next working day

static TemporalAdjuster nextWorkingDay() {
    return temporal -> {
        var workingDay = temporal;
        switch (DayOfWeek.of(temporal.get(DAY_OF_WEEK))) {
            case SUNDAY: {
                workingDay = temporal.plus(1, DAYS);
                break;
            }
            case SATURDAY: {
                workingDay = temporal.plus(2, DAYS);
                break;
            }
        }
        return workingDay;
    };
}

find the first working day of month

static TemporalAdjuster firstWorkingDayOfMonth() {
    return temporal -> nextWorkingDay().adjustInto(temporal.with(TemporalAdjusters.firstDayOfMonth()));
}

tests

@Test
public void firstWorkingDayOfMonth_starts_not_weekend() {
    assertThat(LocalDate.parse("2019-01-15").with(CustomAdjusters.firstWorkingDayOfMonth()), 
            is(LocalDate.parse("2019-01-01")));
}

@Test
public void firstWorkingDayOfMonth_starts_saturday() {
    assertThat(LocalDate.parse("2019-06-15").with(CustomAdjusters.firstWorkingDayOfMonth()),
            is(LocalDate.parse("2019-06-03")));
}

@Test
public void firstWorkingDayOfMonth_starts_sunday() {
    assertThat(LocalDate.parse("2019-09-15").with(CustomAdjusters.firstWorkingDayOfMonth()),
            is(LocalDate.parse("2019-09-02")));
}

@Test
public void firstWorkingDayOfMonth_weekend() {
    assertThat(LocalDate.parse("2019-01-03").with(CustomAdjusters.nextWorkingDay()),
            is(LocalDate.parse("2019-01-03")));
}

@Test
public void firstWorkingDayOfMonth_saturday() {
    assertThat(LocalDate.parse("2019-01-05").with(CustomAdjusters.nextWorkingDay()),
            is(LocalDate.parse("2019-01-07")));
}

@Test
public void firstWorkingDayOfMonth_sunday() {
    assertThat(LocalDate.parse("2019-01-06").with(CustomAdjusters.nextWorkingDay()),
            is(LocalDate.parse("2019-01-07")));
}

mtumilowicz/java8-datetime-temporaladjusters

java8-datetime-temporaladjusters

preview

project description