旧日時APIとの相互変換＆Java 6／7でDate-Time APIが使えるライブラリThreeTen Backport：ここが大変だよJava 8 Date-Time API（終）（3/3 ページ）

<dependency>
    <groupId>org.threeten</groupId>
    <artifactId>threetenbp</artifactId>
    <version>1.2</version>
</dependency>

package jp.co.atmark.datetimeapi.sample03;
 
import java.time.LocalDateTime;
import java.time.Period;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.time.temporal.ChronoUnit;
 
public class ThreetenSample01 {
    
    public static void main(String[] args) {
 
        System.out.println("LocalDateTimeの例");
        LocalDateTime localDateTime1 = LocalDateTime.of(2014, 1, 1, 0, 0, 0, 0);
        LocalDateTime localDateTime2 = LocalDateTime.of(2014, 2, 28, 3, 4, 5, 6);
        System.out.println("localDateTime1=" + localDateTime1);
        System.out.println("localDateTime2=" + localDateTime2);
 
        System.out.println();
        System.out.println("ZonedDateTimeの例");
        ZonedDateTime zonedDateTime1 = ZonedDateTime.of(localDateTime1, ZoneId.of("UTC"));
        ZonedDateTime zonedDateTime2 = ZonedDateTime.of(localDateTime2, ZoneId.systemDefault());
        System.out.println("zonedDateTime1=" + zonedDateTime1);
        System.out.println("zonedDateTime2=" + zonedDateTime2);
 
        System.out.println();
        System.out.println("日数の計算");
        Period period = Period.between(localDateTime1.toLocalDate(), localDateTime2.toLocalDate());
        System.out.println("Period.between(localDateTime1.toLocalDate(), localDateTime2.toLocalDate())=" + period);
 
        long days = ChronoUnit.DAYS.between(localDateTime1, localDateTime2);
        System.out.println("ChronoUnit.DAYS.between(localDateTime1, localDateTime2)=" + days);
        System.out.println();
        System.out.println("Formatterの例");
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("uuuu/M/d HH:mm:ss");
        System.out.println("formatter.format(localDateTime1)=" + formatter.format(localDateTime1));
        System.out.println("formatter.format(localDateTime2)=" + formatter.format(localDateTime2));
    }
}

package jp.co.atmark.datetimeapi.sample03;
 
import org.threeten.bp.LocalDateTime;
import org.threeten.bp.Period;
import org.threeten.bp.ZoneId;
import org.threeten.bp.ZonedDateTime;
import org.threeten.bp.format.DateTimeFormatter;
import org.threeten.bp.temporal.ChronoUnit;
 
public class ThreeTenSample01 {
 
    public static void main(String[] args) {
 
……省略（サンプル1と同じ記述）……
 
    }
}

package jp.co.atmark.datetimeapi.sample03;
 
import org.threeten.bp.LocalDateTime;
import org.threeten.bp.OffsetTime;
import org.threeten.bp.ZoneId;
import org.threeten.bp.ZonedDateTime;
 
public class ThreeTenSample02 {
 
    public static void main(String[] args) {
        LocalDateTime localDateTime = LocalDateTime.now();
        ZonedDateTime zonedDateTime = ZonedDateTime.of(localDateTime, ZoneId.of("America/Los_Angeles"));
        OffsetTime offsetTime = zonedDateTime.query(OffsetTime.FROM);
 
        System.out.println("localDateTime=" + localDateTime);
        System.out.println("zonedDateTime=" + zonedDateTime);
        System.out.println("offsetTime=" + offsetTime);
    }
}

LocalDate localDate = LocalDate.of(2014, 12, 25);
JapaneseDate japaneseDate = JapaneseDate.from(localDate);
 
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("GGGG yy/MM/dd");
 
System.out.println(localDate.format(formatter));
System.out.println(japaneseDate.format(formatter));