Java 8 – TemporalAdjustersの例
Java 8では、あらかじめ定義された `java.time.temporal.TemporalAdjusters`を使用して日付を調整したり、https://docs.oracle.com/javase/8/docs/api/java/time/temporal/Temporal.htmlを調整することができます[時代]
1.時間的調節器
firstDayOfMonth、firstDayOfNextMonth、次の月曜日などに日付を移動する例
TestDate.java
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); } }
出力
current date : 2016-11-15 firstDayOfMonth : 2016-11-01 lastDayOfMonth : 2016-11-30 next monday : 2016-11-21 firstDayOfNextMonth : 2016-12-01
2.カスタムTemporalAdjuster
次のクリスマスに日付を移動するための `TemporalAdjuster`を実装する例
NextChristmas.java
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); } }
TestDate.java
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); } }
出力
current date : 2016-11-15 Next Christmas : 2016-12-25
または、次のラムダ式を使用することもできます。
localDate = localDate.with( temporal -> temporal.with(ChronoField.MONTH__OF__YEAR, 12).with(ChronoField.DAY__OF__MONTH, 25) );
参考文献
-
リンク://java8/java-8-hijrahdate-how-to-calculate-the-ramadan-date/[Java
8 – HijrahDate、ラマダン日付の計算方法]。
https://docs/
JavaDoc]。
https://docs.oracle.com/javase/8/docs/api/java/time/temporal/TemporalAdjusters.html
[TemporalAdjusters
JavaDoc]。
https://docs.oracle.com/javase/8/docs/api/java/time/temporal/Temporal.html
[Temporal
JavaDoc]。
Wikipediaクリスマス
リンク://タグ/日付/[日付]リンク://タグ/java-time/[java.time]リンク://タグ/java8/[java8]
TemporalAdjusters