Java 8 – TemporalAdjusters examples

In Java 8, you can use the predefined java.time.temporal.TemporalAdjusters to adjust a date or Temporal

1. TemporalAdjusters

Example to move a date to firstDayOfMonth, firstDayOfNextMonth, next Monday and etc.

package com.mkyong.time;

import java.time.DayOfWeek;
import java.time.LocalDate;
import java.time.temporal.TemporalAdjusters;

public class TestDate {

    public static void main(String[] args) {

        LocalDate localDate = LocalDate.now();
        System.out.println("current date : " + localDate);

        LocalDate with = localDate.with(TemporalAdjusters.firstDayOfMonth());
        System.out.println("firstDayOfMonth : " + with);

        LocalDate with1 = localDate.with(TemporalAdjusters.lastDayOfMonth());
        System.out.println("lastDayOfMonth : " + with1);

        LocalDate with2 = localDate.with(TemporalAdjusters.next(DayOfWeek.MONDAY));
        System.out.println("next monday : " + with2);

        LocalDate with3 = localDate.with(TemporalAdjusters.firstDayOfNextMonth());
        System.out.println("firstDayOfNextMonth : " + with3);

    }

}

Output

current date : 2016-11-15
firstDayOfMonth : 2016-11-01
lastDayOfMonth : 2016-11-30
next monday : 2016-11-21
firstDayOfNextMonth : 2016-12-01

2. Custom TemporalAdjuster

Example to implement TemporalAdjuster to move a date to next Christmas.

package com.mkyong.time;

import java.time.temporal.ChronoField;
import java.time.temporal.Temporal;
import java.time.temporal.TemporalAdjuster;

public class NextChristmas implements TemporalAdjuster {

    @Override
    public Temporal adjustInto(Temporal temporal) {

        return temporal.with(ChronoField.MONTH_OF_YEAR, 12).with(ChronoField.DAY_OF_MONTH, 25);

    }
}

package com.mkyong.time;

import java.time.LocalDate;

public class TestDate {

    public static void main(String[] args) {

        LocalDate localDate = LocalDate.now();
        System.out.println("current date : " + localDate);

        localDate = localDate.with(new NextChristmas());
        System.out.println("Next Christmas : " + localDate);

    }

}

Output

current date : 2016-11-15
Next Christmas : 2016-12-25

Alternatively, you can use the following lambda expression :

	localDate = localDate.with(
		temporal -> temporal.with(ChronoField.MONTH_OF_YEAR, 12).with(ChronoField.DAY_OF_MONTH, 25)
	);

References

1. Java 8 – HijrahDate, How to calculate the Ramadan date
2. TemporalAdjuster JavaDoc
3. TemporalAdjusters JavaDoc
4. Temporal JavaDoc
5. Wikipedia Christmas