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Start using java.time classes
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‎src/main/java/com/kosherjava/zmanim/hebrewcalendar/YerushalmiYomiCalculator.java‎

Lines changed: 134 additions & 148 deletions
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@@ -15,9 +15,8 @@
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*/
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package com.kosherjava.zmanim.hebrewcalendar;
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import java.util.Calendar;
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import java.util.GregorianCalendar;
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import java.time.ZoneId;
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import java.time.ZonedDateTime;
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/**
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* This class calculates the <a href="https://en.wikipedia.org/wiki/Jerusalem_Talmud">Talmud Yerusalmi</a> <a href=
@@ -27,149 +26,136 @@
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* @author &copy; Eliyahu Hershfeld 2017 - 2025
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*/
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public class YerushalmiYomiCalculator {
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/**
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* The start date of the first Daf Yomi Yerushalmi cycle of February 2, 1980 / 15 Shevat, 5740.
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*/
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private final static Calendar DAF_YOMI_START_DAY = new GregorianCalendar(1980, Calendar.FEBRUARY, 2);
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/** The number of milliseconds in a day. */
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private final static int DAY_MILIS = 1000 * 60 * 60 * 24;
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/** The number of pages in the Talmud Yerushalmi.*/
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private final static int WHOLE_SHAS_DAFS = 1554;
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/** The number of pages per <em>masechta</em> (tractate).*/
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private final static int[] BLATT_PER_MASECHTA = {
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68, 37, 34, 44, 31, 59, 26, 33, 28, 20, 13, 92, 65, 71, 22, 22, 42, 26, 26, 33, 34, 22,
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19, 85, 72, 47, 40, 47, 54, 48, 44, 37, 34, 44, 9, 57, 37, 19, 13};
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/**
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* Default constructor.
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*/
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public YerushalmiYomiCalculator() {
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// nothing here
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}
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/**
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* Returns the <a href="https://en.wikipedia.org/wiki/Daf_Yomi">Daf Yomi</a>
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* <a href="https://en.wikipedia.org/wiki/Jerusalem_Talmud">Yerusalmi</a> page ({@link Daf}) for a given date.
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* The first Daf Yomi cycle started on 15 Shevat (Tu Bishvat), 5740 (February, 2, 1980) and calculations
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* prior to this date will result in an IllegalArgumentException thrown. A null will be returned on Tisha B'Av or
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* Yom Kippur.
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*
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* @param calendar
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* the calendar date for calculation
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* @return the {@link Daf} or null if the date is on Tisha B'Av or Yom Kippur.
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*
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* @throws IllegalArgumentException
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* if the date is prior to the February 2, 1980, the start of the first Daf Yomi Yerushalmi cycle
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*/
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public static Daf getDafYomiYerushalmi(JewishCalendar calendar) {
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Calendar nextCycle = new GregorianCalendar();
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Calendar prevCycle = new GregorianCalendar();
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Calendar requested = calendar.getGregorianCalendar();
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int masechta = 0;
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Daf dafYomi = null;
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// There isn't Daf Yomi on Yom Kippur or Tisha B'Av.
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if ( calendar.getYomTovIndex() == JewishCalendar.YOM_KIPPUR ||
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calendar.getYomTovIndex() == JewishCalendar.TISHA_BEAV ) {
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return null;
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}
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if (requested.before(DAF_YOMI_START_DAY)) {
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throw new IllegalArgumentException(requested + " is prior to organized Daf Yomi Yerushalmi cycles that started on "
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+ DAF_YOMI_START_DAY);
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}
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// Start to calculate current cycle. init the start day
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nextCycle.setTime(DAF_YOMI_START_DAY.getTime());
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// Go cycle by cycle, until we get the next cycle
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while (requested.after(nextCycle)) {
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prevCycle.setTime(nextCycle.getTime());
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// Adds the number of whole shas dafs. and the number of days that not have daf.
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nextCycle.add(Calendar.DAY_OF_MONTH, WHOLE_SHAS_DAFS);
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nextCycle.add(Calendar.DAY_OF_MONTH, getNumOfSpecialDays(prevCycle, nextCycle));
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}
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// Get the number of days from cycle start until request.
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int dafNo = (int)(getDiffBetweenDays(prevCycle, requested));
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// Get the number of special day to subtract
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int specialDays = getNumOfSpecialDays(prevCycle, requested);
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int total = dafNo - specialDays;
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// Finally find the daf.
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for (int i : BLATT_PER_MASECHTA) {
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if (total < i) {
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dafYomi = new Daf(masechta, total + 1);
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break;
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}
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total -= i;
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masechta++;
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}
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return dafYomi;
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}
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/**
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* Return the number of special days (Yom Kippur and Tisha Beav, where there are no dafim), between the start date
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* (as a <code>Calendar</code>) and end date (also as a <code>Calendar</code>).
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*
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* @param start date to start calculating from
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* @param end date to finish calculating at
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* @return the number of special days between the start and end dates
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*/
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private static int getNumOfSpecialDays(Calendar start, Calendar end) {
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// Find the start and end Jewish years
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int startYear = new JewishCalendar(start).getJewishYear();
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int endYear = new JewishCalendar(end).getJewishYear();
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// Value to return
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int specialDays = 0;
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//Instant of special Dates
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JewishCalendar yom_kippur = new JewishCalendar(5770, 7, 10);
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JewishCalendar tisha_beav = new JewishCalendar(5770, 5, 9);
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// Go over the years and find special dates
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for (int i = startYear; i <= endYear; i++) {
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yom_kippur.setJewishYear(i);
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tisha_beav.setJewishYear(i);
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if (isBetween(start, yom_kippur.getGregorianCalendar(), end)) {
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specialDays++;
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}
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if (isBetween(start, tisha_beav.getGregorianCalendar(), end)) {
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specialDays++;
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}
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}
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return specialDays;
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}
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/**
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* Return if the date is between two dates
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*
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* @param start the start date
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* @param date the date being compared
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* @param end the end date
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* @return if the date is between the start and end dates
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*/
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private static boolean isBetween(Calendar start, Calendar date, Calendar end ) {
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return start.before(date) && end.after(date);
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}
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/**
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* Return the number of days between the dates passed in
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* @param start the start date
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* @param end the end date
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* @return the number of days between the start and end dates
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*/
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private static long getDiffBetweenDays(Calendar start, Calendar end) {
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return (end.getTimeInMillis() - start.getTimeInMillis()) / DAY_MILIS;
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}
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/** Start date of first Daf Yomi Yerushalmi cycle: 1980-02-02 */
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private static final ZonedDateTime DAF_YOMI_START_DAY =
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ZonedDateTime.of(1980, 2, 2, 0, 0, 0, 0, ZoneId.systemDefault());
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/** milliseconds in a day*/
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private static final int DAY_MILLIS = 1000 * 60 * 60 * 24;
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/** number of pages (<em>blatt/dafim</em>) in <em>Shas</em>*/
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private static final int WHOLE_SHAS_DAFS = 1554;
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/** number of pages (<em>blatt/dafim</em>) per <em>masechta</em>*/
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private static final int[] BLATT_PER_MASECHTA = {
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68, 37, 34, 44, 31, 59, 26, 33, 28, 20, 13, 92, 65, 71, 22, 22, 42, 26, 26, 33, 34, 22,
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19, 85, 72, 47, 40, 47, 54, 48, 44, 37, 34, 44, 9, 57, 37, 19, 13
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};
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/**
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* Default constructor.
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*/
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public YerushalmiYomiCalculator() {
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// No-op
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}
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/**
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* Returns the Daf Yomi Yerushalmi page for a given Jewish date.
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* Returns null on Yom Kippur or Tisha B’Av.
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* @param jewishCalendar the <code>JewishCalendar</code> to set.
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* @return the daf.
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*/
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public static Daf getDafYomiYerushalmi(JewishCalendar jewishCalendar) {
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ZonedDateTime requested = jewishCalendar.getGregorianCalendar().toInstant()
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.atZone(ZoneId.systemDefault());
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int masechta = 0;
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Daf dafYomi = null;
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// No Daf Yomi on Yom Kippur or Tisha B'Av
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if (jewishCalendar.getYomTovIndex() == JewishCalendar.YOM_KIPPUR ||
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jewishCalendar.getYomTovIndex() == JewishCalendar.TISHA_BEAV) {
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return null;
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}
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if (requested.isBefore(DAF_YOMI_START_DAY)) {
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throw new IllegalArgumentException(requested + " is prior to the first Daf Yomi cycle starting on "
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+ DAF_YOMI_START_DAY);
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}
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// Initialize cycle dates
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ZonedDateTime nextCycle = DAF_YOMI_START_DAY;
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ZonedDateTime prevCycle = DAF_YOMI_START_DAY;
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// Loop through cycles until we reach the requested date
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while (requested.isAfter(nextCycle)) {
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prevCycle = nextCycle;
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// Add whole cycle days
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nextCycle = nextCycle.plusDays(WHOLE_SHAS_DAFS);
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nextCycle = nextCycle.plusDays(getNumOfSpecialDays(prevCycle, nextCycle));
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}
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// Days between start of cycle and requested date
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int dafNo = (int) getDiffBetweenDays(prevCycle, requested);
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int specialDays = getNumOfSpecialDays(prevCycle, requested);
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int total = dafNo - specialDays;
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// Find the daf
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for (int blatt : BLATT_PER_MASECHTA) {
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if (total < blatt) {
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dafYomi = new Daf(masechta, total + 1);
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break;
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}
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total -= blatt;
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masechta++;
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}
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return dafYomi;
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}
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/**
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* Counts the number of "special days" (Yom Kippur, Tisha B’Av) between two ZonedDateTimes.
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* @param start the start date for the calculation
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* @param end the start date for the calculatio
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* @return the number of special days
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*/
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private static int getNumOfSpecialDays(ZonedDateTime start, ZonedDateTime end) {
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int startYear = new JewishCalendar(start).getJewishYear();
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int endYear = new JewishCalendar(end).getJewishYear();
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int specialDays = 0;
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// Loop over each Jewish year in range
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for (int year = startYear; year <= endYear; year++) {
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// Create Yom Kippur and Tisha B’Av for that Jewish year
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JewishCalendar yomKippur = new JewishCalendar(5770, 7, 10); // month/day are constants
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JewishCalendar tishaBeav = new JewishCalendar(5770, 5, 9);
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yomKippur.setJewishYear(year);
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tishaBeav.setJewishYear(year);
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ZonedDateTime ykDate = yomKippur.getGregorianCalendar().toInstant()
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.atZone(start.getZone());
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ZonedDateTime tbDate = tishaBeav.getGregorianCalendar().toInstant()
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.atZone(start.getZone());
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if (isBetween(start, ykDate, end)) specialDays++;
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if (isBetween(start, tbDate, end)) specialDays++;
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}
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return specialDays;
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}
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/**
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* Checks if a date is strictly between start and end.
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* @param start the start <code>ZonedDateTime</code>
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* @param date the <code>ZonedDateTime</code> to check
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* @param end the end <code>ZonedDateTime</code>
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* @return if the date is between the two dates
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*/
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private static boolean isBetween(ZonedDateTime start, ZonedDateTime date, ZonedDateTime end) {
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return start.isBefore(date) && end.isAfter(date);
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}
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/**
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* Returns the number of full days between two <code>ZonedDateTime</code>s.
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* @param start the start <code>ZonedDateTime</code>
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* @param end the end <code>ZonedDateTime</code>
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* @return the number of days between the dates.
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*/
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private static long getDiffBetweenDays(ZonedDateTime start, ZonedDateTime end) {
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return (end.toInstant().toEpochMilli() - start.toInstant().toEpochMilli()) / DAY_MILLIS;
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}
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}

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