Руководство Java HijrahDate

AH = (CE − 622) × 33 ÷ 32

CE = AH + 622 − (AH ÷ 32)

LocalDate localDate = LocalDate.of(2000, 1, 1);
HijrahDate hijrahDate = HijrahDate.from(localDate);

System.out.printf("localDate: %s%n", localDate); // 2000-01-01
System.out.printf("hijrahDate: %s%n%n", hijrahDate); // Hijrah-umalqura AH 1420-09-24

HijrahEra era = hijrahDate.getEra(); // HijrahEra.AH
System.out.printf(" > era.name(): %s%n%n", era.name()); // AH

HijrahChronology chronology = hijrahDate.getChronology();
System.out.printf(" > chronology.getId(): %s%n", chronology.getId()); // Hijrah-umalqura
System.out.printf(" > chronology.getCalendarType(): %s", chronology.getCalendarType()); // islamic-umalqura

package org.o7planning.hijrahdate.ex;

import java.time.LocalDate;
import java.time.chrono.Chronology;
import java.time.chrono.HijrahChronology;
import java.time.chrono.HijrahDate;
import java.time.temporal.ChronoField;
import java.time.temporal.TemporalAdjusters;
import java.time.temporal.ValueRange;

public class HijrahDate_date_range_ex1 {
    public static void main(String[] args) {
        Chronology chronology = HijrahChronology.INSTANCE;
        ValueRange range = chronology.range(ChronoField.YEAR);
        int minYear = (int) range.getMinimum();
        int maxYear = (int) range.getMaximum();

        System.out.println("minYear: " + minYear);
        System.out.println("maxYear: " + maxYear);

        // ----- Find the first supported date --------
        // A Hijrah Month have 29 or 30 days.
        HijrahDate hijrahDate = null;
        try {
            hijrahDate = HijrahDate.of(minYear, 12, 30);
        } catch (Exception e) {
            hijrahDate = HijrahDate.of(minYear, 12, 29);
        }
        HijrahDate firstDate = hijrahDate.with(TemporalAdjusters.firstDayOfYear());
        System.out.println("First date: " + firstDate + " --> " + LocalDate.from(firstDate));

        // ----- Find the last supported date --------
        hijrahDate = HijrahDate.of(maxYear, 1, 1);

        hijrahDate.range(ChronoField.DAY_OF_YEAR);
        HijrahDate lastDate = hijrahDate.with(TemporalAdjusters.lastDayOfYear());
        System.out.println("Last date: " + lastDate + " --> " + LocalDate.from(lastDate));
    }
}

int[] hijrahYears = new int[] { 1441, 1442, 1443, 1444, 1445 };

HijrahDate hijrahDate = HijrahDate.of(hijrahYears[0], 1, 1);
System.out.println("Hijrah Year: " + hijrahYears[0]); // 1441
System.out.println("ISO Year: " + LocalDate.from(hijrahDate).getYear()); // 2019
System.out.println();

for (int month = 1; month <= 12; month++) {
    for (int hijrahYear : hijrahYears) {
        hijrahDate = HijrahDate.of(hijrahYear, month, 1);

        System.out.printf("Year: %s  Month: %s  --> %d%n", hijrahYear, month, hijrahDate.lengthOfMonth());
    }
}