jdk/src/share/classes/java/time/chrono/HijrahChronology.java
changeset 15658 55b829ca2334
child 16852 60207b2b4b42
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/java/time/chrono/HijrahChronology.java	Tue Feb 12 09:25:43 2013 -0800
@@ -0,0 +1,1383 @@
+/*
+ * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * Copyright (c) 2012, Stephen Colebourne & Michael Nascimento Santos
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *  * Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *
+ *  * Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ *  * Neither the name of JSR-310 nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package java.time.chrono;
+
+import static java.time.temporal.ChronoField.EPOCH_DAY;
+
+import java.io.IOException;
+import java.io.Serializable;
+import java.text.ParseException;
+import java.time.Clock;
+import java.time.DateTimeException;
+import java.time.Instant;
+import java.time.LocalDate;
+import java.time.ZoneId;
+import java.time.temporal.ChronoField;
+import java.time.temporal.TemporalAccessor;
+import java.time.temporal.ValueRange;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Locale;
+
+/**
+ * The Hijrah calendar system.
+ * <p>
+ * This chronology defines the rules of the Hijrah calendar system.
+ * <p>
+ * The implementation follows the Freeman-Grenville algorithm (*1) and has following features.
+ * <p><ul>
+ * <li>A year has 12 months.</li>
+ * <li>Over a cycle of 30 years there are 11 leap years.</li>
+ * <li>There are 30 days in month number 1, 3, 5, 7, 9, and 11,
+ * and 29 days in month number 2, 4, 6, 8, 10, and 12.</li>
+ * <li>In a leap year month 12 has 30 days.</li>
+ * <li>In a 30 year cycle, year 2, 5, 7, 10, 13, 16, 18, 21, 24,
+ * 26, and 29 are leap years.</li>
+ * <li>Total of 10631 days in a 30 years cycle.</li>
+ * </ul><p>
+ * <P>
+ * The table shows the features described above.
+ * <blockquote>
+ * <table border="1">
+ *   <caption>Hijrah Calendar Months</caption>
+ *   <tbody>
+ *     <tr>
+ *       <th># of month</th>
+ *       <th>Name of month</th>
+ *       <th>Number of days</th>
+ *     </tr>
+ *     <tr>
+ *       <td>1</td>
+ *       <td>Muharram</td>
+ *       <td>30</td>
+ *     </tr>
+ *     <tr>
+ *       <td>2</td>
+ *       <td>Safar</td>
+ *       <td>29</td>
+ *     </tr>
+ *     <tr>
+ *       <td>3</td>
+ *       <td>Rabi'al-Awwal</td>
+ *       <td>30</td>
+ *     </tr>
+ *     <tr>
+ *       <td>4</td>
+ *       <td>Rabi'ath-Thani</td>
+ *       <td>29</td>
+ *     </tr>
+ *     <tr>
+ *       <td>5</td>
+ *       <td>Jumada l-Ula</td>
+ *       <td>30</td>
+ *     </tr>
+ *     <tr>
+ *       <td>6</td>
+ *       <td>Jumada t-Tania</td>
+ *       <td>29</td>
+ *     </tr>
+ *     <tr>
+ *       <td>7</td>
+ *       <td>Rajab</td>
+ *       <td>30</td>
+ *     </tr>
+ *     <tr>
+ *       <td>8</td>
+ *       <td>Sha`ban</td>
+ *       <td>29</td>
+ *     </tr>
+ *     <tr>
+ *       <td>9</td>
+ *       <td>Ramadan</td>
+ *       <td>30</td>
+ *     </tr>
+ *     <tr>
+ *       <td>10</td>
+ *       <td>Shawwal</td>
+ *       <td>29</td>
+ *     </tr>
+ *     <tr>
+ *       <td>11</td>
+ *       <td>Dhu 'l-Qa`da</td>
+ *       <td>30</td>
+ *     </tr>
+ *     <tr>
+ *       <td>12</td>
+ *       <td>Dhu 'l-Hijja</td>
+ *       <td>29, but 30 days in years 2, 5, 7, 10,<br>
+ * 13, 16, 18, 21, 24, 26, and 29</td>
+ *     </tr>
+ *   </tbody>
+ * </table>
+ * </blockquote>
+ * <p>
+ * (*1) The algorithm is taken from the book,
+ * The Muslim and Christian Calendars by G.S.P. Freeman-Grenville.
+ * <p>
+ *
+ * <h3>Specification for implementors</h3>
+ * This class is immutable and thread-safe.
+ *
+ * @since 1.8
+ */
+public final class HijrahChronology extends Chronology implements Serializable {
+
+    /**
+     * The Hijrah Calendar id.
+     */
+    private final String typeId;
+
+    /**
+     * The Hijrah calendarType.
+     */
+    private final String calendarType;
+
+    /**
+     * The singleton instance for the era before the current one - Before Hijrah -
+     * which has the value 0.
+     */
+    public static final Era ERA_BEFORE_AH = HijrahEra.BEFORE_AH;
+    /**
+     * The singleton instance for the current era - Hijrah - which has the value 1.
+     */
+    public static final Era ERA_AH = HijrahEra.AH;
+    /**
+     * Serialization version.
+     */
+    private static final long serialVersionUID = 3127340209035924785L;
+    /**
+     * The minimum valid year-of-era.
+     */
+    public static final int MIN_YEAR_OF_ERA = 1;
+    /**
+     * The maximum valid year-of-era.
+     * This is currently set to 9999 but may be changed to increase the valid range
+     * in a future version of the specification.
+     */
+    public static final int MAX_YEAR_OF_ERA = 9999;
+
+    /**
+     * Number of Gregorian day of July 19, year 622 (Gregorian), which is epoch day
+     * of Hijrah calendar.
+     */
+    private static final int HIJRAH_JAN_1_1_GREGORIAN_DAY = -492148;
+    /**
+     * 0-based, for number of day-of-year in the beginning of month in normal
+     * year.
+     */
+    private static final int NUM_DAYS[] =
+        {0, 30, 59, 89, 118, 148, 177, 207, 236, 266, 295, 325};
+    /**
+     * 0-based, for number of day-of-year in the beginning of month in leap year.
+     */
+    private static final int LEAP_NUM_DAYS[] =
+        {0, 30, 59, 89, 118, 148, 177, 207, 236, 266, 295, 325};
+    /**
+     * 0-based, for day-of-month in normal year.
+     */
+    private static final int MONTH_LENGTH[] =
+        {30, 29, 30, 29, 30, 29, 30, 29, 30, 29, 30, 29};
+    /**
+     * 0-based, for day-of-month in leap year.
+     */
+    private static final int LEAP_MONTH_LENGTH[] =
+        {30, 29, 30, 29, 30, 29, 30, 29, 30, 29, 30, 30};
+
+    /**
+     * <pre>
+     *                            Greatest       Least
+     * Field name        Minimum   Minimum     Maximum     Maximum
+     * ----------        -------   -------     -------     -------
+     * ERA                     0         0           1           1
+     * YEAR_OF_ERA             1         1        9999        9999
+     * MONTH_OF_YEAR           1         1          12          12
+     * DAY_OF_MONTH            1         1          29          30
+     * DAY_OF_YEAR             1         1         354         355
+     * </pre>
+     *
+     * Minimum values.
+     */
+    private static final int MIN_VALUES[] =
+        {
+        0,
+        MIN_YEAR_OF_ERA,
+        0,
+        1,
+        0,
+        1,
+        1
+        };
+
+    /**
+     * Least maximum values.
+     */
+    private static final int LEAST_MAX_VALUES[] =
+        {
+        1,
+        MAX_YEAR_OF_ERA,
+        11,
+        51,
+        5,
+        29,
+        354
+        };
+
+    /**
+     * Maximum values.
+     */
+    private static final int MAX_VALUES[] =
+        {
+        1,
+        MAX_YEAR_OF_ERA,
+        11,
+        52,
+        6,
+        30,
+        355
+        };
+
+   /**
+     * Position of day-of-month. This value is used to get the min/max value
+     * from an array.
+     */
+    private static final int POSITION_DAY_OF_MONTH = 5;
+    /**
+     * Position of day-of-year. This value is used to get the min/max value from
+     * an array.
+     */
+    private static final int POSITION_DAY_OF_YEAR = 6;
+    /**
+     * Zero-based start date of cycle year.
+     */
+    private static final int CYCLEYEAR_START_DATE[] =
+        {
+        0,
+        354,
+        709,
+        1063,
+        1417,
+        1772,
+        2126,
+        2481,
+        2835,
+        3189,
+        3544,
+        3898,
+        4252,
+        4607,
+        4961,
+        5315,
+        5670,
+        6024,
+        6379,
+        6733,
+        7087,
+        7442,
+        7796,
+        8150,
+        8505,
+        8859,
+        9214,
+        9568,
+        9922,
+        10277
+        };
+
+    /**
+     * Holding the adjusted month days in year. The key is a year (Integer) and
+     * the value is the all the month days in year (int[]).
+     */
+    private final HashMap<Integer, int[]> ADJUSTED_MONTH_DAYS = new HashMap<>();
+    /**
+     * Holding the adjusted month length in year. The key is a year (Integer)
+     * and the value is the all the month length in year (int[]).
+     */
+    private final HashMap<Integer, int[]> ADJUSTED_MONTH_LENGTHS = new HashMap<>();
+    /**
+     * Holding the adjusted days in the 30 year cycle. The key is a cycle number
+     * (Integer) and the value is the all the starting days of the year in the
+     * cycle (int[]).
+     */
+    private final HashMap<Integer, int[]> ADJUSTED_CYCLE_YEARS = new HashMap<>();
+    /**
+     * Holding the adjusted cycle in the 1 - 30000 year. The key is the cycle
+     * number (Integer) and the value is the starting days in the cycle in the
+     * term.
+     */
+    private final long[] ADJUSTED_CYCLES;
+    /**
+     * Holding the adjusted min values.
+     */
+    private final int[] ADJUSTED_MIN_VALUES;
+    /**
+     * Holding the adjusted max least max values.
+     */
+    private final int[] ADJUSTED_LEAST_MAX_VALUES;
+    /**
+     * Holding adjusted max values.
+     */
+    private final int[] ADJUSTED_MAX_VALUES;
+    /**
+     * Holding the non-adjusted month days in year for non leap year.
+     */
+    private static final int[] DEFAULT_MONTH_DAYS;
+    /**
+     * Holding the non-adjusted month days in year for leap year.
+     */
+    private static final int[] DEFAULT_LEAP_MONTH_DAYS;
+    /**
+     * Holding the non-adjusted month length for non leap year.
+     */
+    private static final int[] DEFAULT_MONTH_LENGTHS;
+    /**
+     * Holding the non-adjusted month length for leap year.
+     */
+    private static final int[] DEFAULT_LEAP_MONTH_LENGTHS;
+    /**
+     * Holding the non-adjusted 30 year cycle starting day.
+     */
+    private static final int[] DEFAULT_CYCLE_YEARS;
+    /**
+     * number of 30-year cycles to hold the deviation data.
+     */
+    private static final int MAX_ADJUSTED_CYCLE = 334; // to support year 9999
+
+
+    /**
+     * Narrow names for eras.
+     */
+    private static final HashMap<String, String[]> ERA_NARROW_NAMES = new HashMap<>();
+    /**
+     * Short names for eras.
+     */
+    private static final HashMap<String, String[]> ERA_SHORT_NAMES = new HashMap<>();
+    /**
+     * Full names for eras.
+     */
+    private static final HashMap<String, String[]> ERA_FULL_NAMES = new HashMap<>();
+    /**
+     * Fallback language for the era names.
+     */
+    private static final String FALLBACK_LANGUAGE = "en";
+
+    /**
+     * Singleton instance of the Hijrah chronology.
+     * Must be initialized after the rest of the static initialization.
+     */
+    public static final HijrahChronology INSTANCE;
+
+    /**
+     * Name data.
+     */
+    static {
+        ERA_NARROW_NAMES.put(FALLBACK_LANGUAGE, new String[]{"BH", "HE"});
+        ERA_SHORT_NAMES.put(FALLBACK_LANGUAGE, new String[]{"B.H.", "H.E."});
+        ERA_FULL_NAMES.put(FALLBACK_LANGUAGE, new String[]{"Before Hijrah", "Hijrah Era"});
+
+        DEFAULT_MONTH_DAYS = Arrays.copyOf(NUM_DAYS, NUM_DAYS.length);
+
+        DEFAULT_LEAP_MONTH_DAYS = Arrays.copyOf(LEAP_NUM_DAYS, LEAP_NUM_DAYS.length);
+
+        DEFAULT_MONTH_LENGTHS = Arrays.copyOf(MONTH_LENGTH, MONTH_LENGTH.length);
+
+        DEFAULT_LEAP_MONTH_LENGTHS = Arrays.copyOf(LEAP_MONTH_LENGTH, LEAP_MONTH_LENGTH.length);
+
+        DEFAULT_CYCLE_YEARS = Arrays.copyOf(CYCLEYEAR_START_DATE, CYCLEYEAR_START_DATE.length);
+
+        INSTANCE = new HijrahChronology();
+
+        String extraCalendars = java.security.AccessController.doPrivileged(
+            new sun.security.action.GetPropertyAction("java.time.chrono.HijrahCalendars"));
+        if (extraCalendars != null) {
+            try {
+                // Split on whitespace
+                String[] splits = extraCalendars.split("\\s");
+                for (String cal : splits) {
+                    if (!cal.isEmpty()) {
+                        // Split on the delimiter between typeId "-" calendarType
+                        String[] type = cal.split("-");
+                        Chronology cal2 = new HijrahChronology(type[0], type.length > 1 ? type[1] : type[0]);
+                    }
+                }
+            } catch (Exception ex) {
+                // Log the error
+                // ex.printStackTrace();
+            }
+        }
+    }
+
+    /**
+     * Restricted constructor.
+     */
+    private HijrahChronology() {
+        this("Hijrah", "islamicc");
+    }
+    /**
+     * Constructor for name and type HijrahChronology.
+     * @param id the id of the calendar
+     * @param calendarType the calendar type
+     */
+    private HijrahChronology(String id, String calendarType) {
+        this.typeId = id;
+        this.calendarType = calendarType;
+
+        ADJUSTED_CYCLES = new long[MAX_ADJUSTED_CYCLE];
+        for (int i = 0; i < ADJUSTED_CYCLES.length; i++) {
+            ADJUSTED_CYCLES[i] = (10631L * i);
+        }
+        // Initialize min values, least max values and max values.
+        ADJUSTED_MIN_VALUES = Arrays.copyOf(MIN_VALUES, MIN_VALUES.length);
+        ADJUSTED_LEAST_MAX_VALUES = Arrays.copyOf(LEAST_MAX_VALUES, LEAST_MAX_VALUES.length);
+        ADJUSTED_MAX_VALUES = Arrays.copyOf(MAX_VALUES,MAX_VALUES.length);
+
+        try {
+            // Implicitly reads deviation data for this HijrahChronology.
+            boolean any = HijrahDeviationReader.readDeviation(typeId, calendarType, this::addDeviationAsHijrah);
+        } catch (IOException | ParseException e) {
+            // do nothing. Log deviation config errors.
+            //e.printStackTrace();
+        }
+    }
+
+    /**
+     * Resolve singleton.
+     *
+     * @return the singleton instance, not null
+     */
+    private Object readResolve() {
+        return INSTANCE;
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Gets the ID of the chronology - 'Hijrah'.
+     * <p>
+     * The ID uniquely identifies the {@code Chronology}.
+     * It can be used to lookup the {@code Chronology} using {@link #of(String)}.
+     *
+     * @return the chronology ID - 'Hijrah'
+     * @see #getCalendarType()
+     */
+    @Override
+    public String getId() {
+        return typeId;
+    }
+
+    /**
+     * Gets the calendar type of the underlying calendar system - 'islamicc'.
+     * <p>
+     * The calendar type is an identifier defined by the
+     * <em>Unicode Locale Data Markup Language (LDML)</em> specification.
+     * It can be used to lookup the {@code Chronology} using {@link #of(String)}.
+     * It can also be used as part of a locale, accessible via
+     * {@link Locale#getUnicodeLocaleType(String)} with the key 'ca'.
+     *
+     * @return the calendar system type - 'islamicc'
+     * @see #getId()
+     */
+    @Override
+    public String getCalendarType() {
+        return calendarType;
+    }
+
+    //-----------------------------------------------------------------------
+    @Override
+    public HijrahDate date(int prolepticYear, int month, int dayOfMonth) {
+        return HijrahDate.of(this, prolepticYear, month, dayOfMonth);
+    }
+
+    @Override
+    public HijrahDate dateYearDay(int prolepticYear, int dayOfYear) {
+        return HijrahDate.of(this, prolepticYear, 1, 1).plusDays(dayOfYear - 1);  // TODO better
+    }
+
+    @Override
+    public HijrahDate date(TemporalAccessor temporal) {
+        if (temporal instanceof HijrahDate) {
+            return (HijrahDate) temporal;
+        }
+        return HijrahDate.ofEpochDay(this, temporal.getLong(EPOCH_DAY));
+    }
+
+    @Override
+    public HijrahDate date(Era era, int yearOfEra, int month, int dayOfMonth) {
+        return date(prolepticYear(era, yearOfEra), month, dayOfMonth);
+
+    }
+
+    @Override
+    public HijrahDate dateYearDay(Era era, int yearOfEra, int dayOfYear) {
+        return dateYearDay(prolepticYear(era, yearOfEra), dayOfYear);
+    }
+
+    @Override
+    public HijrahDate dateNow() {
+        return dateNow(Clock.systemDefaultZone());
+    }
+
+    @Override
+    public HijrahDate dateNow(ZoneId zone) {
+        return dateNow(Clock.system(zone));
+    }
+
+    @Override
+    public HijrahDate dateNow(Clock clock) {
+        return date(LocalDate.now(clock));
+    }
+
+    @Override
+    public ChronoLocalDateTime<HijrahDate> localDateTime(TemporalAccessor temporal) {
+        return (ChronoLocalDateTime<HijrahDate>)super.localDateTime(temporal);
+    }
+
+    @Override
+    public ChronoZonedDateTime<HijrahDate> zonedDateTime(TemporalAccessor temporal) {
+        return (ChronoZonedDateTime<HijrahDate>)super.zonedDateTime(temporal);
+    }
+
+    @Override
+    public ChronoZonedDateTime<HijrahDate> zonedDateTime(Instant instant, ZoneId zone) {
+        return (ChronoZonedDateTime<HijrahDate>)super.zonedDateTime(instant, zone);
+    }
+
+    //-----------------------------------------------------------------------
+    @Override
+    public boolean isLeapYear(long prolepticYear) {
+        return isLeapYear0(prolepticYear);
+    }
+    /**
+     * Returns if the year is a leap year.
+     * @param prolepticYear he year to compute from
+     * @return {@code true} if the year is a leap year, otherwise {@code false}
+     */
+    private static boolean isLeapYear0(long prolepticYear) {
+        return (14 + 11 * (prolepticYear > 0 ? prolepticYear : -prolepticYear)) % 30 < 11;
+    }
+
+    @Override
+    public int prolepticYear(Era era, int yearOfEra) {
+        if (era instanceof HijrahEra == false) {
+            throw new DateTimeException("Era must be HijrahEra");
+        }
+        return (era == HijrahEra.AH ? yearOfEra : 1 - yearOfEra);
+    }
+
+    @Override
+    public Era eraOf(int eraValue) {
+        switch (eraValue) {
+            case 0:
+                return HijrahEra.BEFORE_AH;
+            case 1:
+                return HijrahEra.AH;
+            default:
+                throw new DateTimeException("invalid Hijrah era");
+        }
+    }
+
+    @Override
+    public List<Era> eras() {
+        return Arrays.<Era>asList(HijrahEra.values());
+    }
+
+    //-----------------------------------------------------------------------
+    @Override
+    public ValueRange range(ChronoField field) {
+        return field.range();
+    }
+
+    /**
+     * Check the validity of a yearOfEra.
+     * @param yearOfEra the year to check
+     */
+    void checkValidYearOfEra(int yearOfEra) {
+         if (yearOfEra < MIN_YEAR_OF_ERA  ||
+                 yearOfEra > MAX_YEAR_OF_ERA) {
+             throw new DateTimeException("Invalid year of Hijrah Era");
+         }
+    }
+
+    void checkValidDayOfYear(int dayOfYear) {
+         if (dayOfYear < 1  ||
+                 dayOfYear > getMaximumDayOfYear()) {
+             throw new DateTimeException("Invalid day of year of Hijrah date");
+         }
+    }
+
+    void checkValidMonth(int month) {
+         if (month < 1 || month > 12) {
+             throw new DateTimeException("Invalid month of Hijrah date");
+         }
+    }
+
+    void checkValidDayOfMonth(int dayOfMonth) {
+         if (dayOfMonth < 1  ||
+                 dayOfMonth > getMaximumDayOfMonth()) {
+             throw new DateTimeException("Invalid day of month of Hijrah date, day "
+                     + dayOfMonth + " greater than " + getMaximumDayOfMonth() + " or less than 1");
+         }
+    }
+
+    //-----------------------------------------------------------------------
+    /**
+     * Returns the int array containing the following field from the julian day.
+     *
+     * int[0] = ERA
+     * int[1] = YEAR
+     * int[2] = MONTH
+     * int[3] = DATE
+     * int[4] = DAY_OF_YEAR
+     * int[5] = DAY_OF_WEEK
+     *
+     * @param gregorianDays  a julian day.
+     */
+    int[] getHijrahDateInfo(long gregorianDays) {
+        int era, year, month, date, dayOfWeek, dayOfYear;
+
+        int cycleNumber, yearInCycle, dayOfCycle;
+
+        long epochDay = gregorianDays - HIJRAH_JAN_1_1_GREGORIAN_DAY;
+
+        if (epochDay >= 0) {
+            cycleNumber = getCycleNumber(epochDay); // 0 - 99.
+            dayOfCycle = getDayOfCycle(epochDay, cycleNumber); // 0 - 10631.
+            yearInCycle = getYearInCycle(cycleNumber, dayOfCycle); // 0 - 29.
+            dayOfYear = getDayOfYear(cycleNumber, dayOfCycle, yearInCycle);
+            // 0 - 354/355
+            year = cycleNumber * 30 + yearInCycle + 1; // 1-based year.
+            month = getMonthOfYear(dayOfYear, year); // 0-based month-of-year
+            date = getDayOfMonth(dayOfYear, month, year); // 0-based date
+            ++date; // Convert from 0-based to 1-based
+            era = HijrahEra.AH.getValue();
+        } else {
+            cycleNumber = (int) epochDay / 10631; // 0 or negative number.
+            dayOfCycle = (int) epochDay % 10631; // -10630 - 0.
+            if (dayOfCycle == 0) {
+                dayOfCycle = -10631;
+                cycleNumber++;
+            }
+            yearInCycle = getYearInCycle(cycleNumber, dayOfCycle); // 0 - 29.
+            dayOfYear = getDayOfYear(cycleNumber, dayOfCycle, yearInCycle);
+            year = cycleNumber * 30 - yearInCycle; // negative number.
+            year = 1 - year;
+            dayOfYear = (isLeapYear(year) ? (dayOfYear + 355)
+                    : (dayOfYear + 354));
+            month = getMonthOfYear(dayOfYear, year);
+            date = getDayOfMonth(dayOfYear, month, year);
+            ++date; // Convert from 0-based to 1-based
+            era = HijrahEra.BEFORE_AH.getValue();
+        }
+        // Hijrah day zero is a Friday
+        dayOfWeek = (int) ((epochDay + 5) % 7);
+        dayOfWeek += (dayOfWeek <= 0) ? 7 : 0;
+
+        int dateInfo[] = new int[6];
+        dateInfo[0] = era;
+        dateInfo[1] = year;
+        dateInfo[2] = month + 1; // change to 1-based.
+        dateInfo[3] = date;
+        dateInfo[4] = dayOfYear + 1; // change to 1-based.
+        dateInfo[5] = dayOfWeek;
+        return dateInfo;
+    }
+
+    /**
+     * Return Gregorian epoch day from Hijrah year, month, and day.
+     *
+     * @param prolepticYear  the year to represent, caller calculated
+     * @param monthOfYear  the month-of-year to represent, caller calculated
+     * @param dayOfMonth  the day-of-month to represent, caller calculated
+     * @return a julian day
+     */
+    long getGregorianEpochDay(int prolepticYear, int monthOfYear, int dayOfMonth) {
+        long day = yearToGregorianEpochDay(prolepticYear);
+        day += getMonthDays(monthOfYear - 1, prolepticYear);
+        day += dayOfMonth;
+        return day;
+    }
+
+    /**
+     * Returns the Gregorian epoch day from the proleptic year
+     * @param prolepticYear the proleptic year
+     * @return the Epoch day
+     */
+    private long yearToGregorianEpochDay(int prolepticYear) {
+
+        int cycleNumber = (prolepticYear - 1) / 30; // 0-based.
+        int yearInCycle = (prolepticYear - 1) % 30; // 0-based.
+
+        int dayInCycle = getAdjustedCycle(cycleNumber)[Math.abs(yearInCycle)]
+                ;
+
+        if (yearInCycle < 0) {
+            dayInCycle = -dayInCycle;
+        }
+
+        Long cycleDays;
+
+        try {
+            cycleDays = ADJUSTED_CYCLES[cycleNumber];
+        } catch (ArrayIndexOutOfBoundsException e) {
+            cycleDays = null;
+        }
+
+        if (cycleDays == null) {
+            cycleDays = new Long(cycleNumber * 10631);
+        }
+
+        return (cycleDays.longValue() + dayInCycle + HIJRAH_JAN_1_1_GREGORIAN_DAY - 1);
+    }
+
+    /**
+     * Returns the 30 year cycle number from the epoch day.
+     *
+     * @param epochDay  an epoch day
+     * @return a cycle number
+     */
+    private int getCycleNumber(long epochDay) {
+        long[] days = ADJUSTED_CYCLES;
+        int cycleNumber;
+        try {
+            for (int i = 0; i < days.length; i++) {
+                if (epochDay < days[i]) {
+                    return i - 1;
+                }
+            }
+            cycleNumber = (int) epochDay / 10631;
+        } catch (ArrayIndexOutOfBoundsException e) {
+            cycleNumber = (int) epochDay / 10631;
+        }
+        return cycleNumber;
+    }
+
+    /**
+     * Returns day of cycle from the epoch day and cycle number.
+     *
+     * @param epochDay  an epoch day
+     * @param cycleNumber  a cycle number
+     * @return a day of cycle
+     */
+    private int getDayOfCycle(long epochDay, int cycleNumber) {
+        Long day;
+
+        try {
+            day = ADJUSTED_CYCLES[cycleNumber];
+        } catch (ArrayIndexOutOfBoundsException e) {
+            day = null;
+        }
+        if (day == null) {
+            day = new Long(cycleNumber * 10631);
+        }
+        return (int) (epochDay - day.longValue());
+    }
+
+    /**
+     * Returns the year in cycle from the cycle number and day of cycle.
+     *
+     * @param cycleNumber  a cycle number
+     * @param dayOfCycle  day of cycle
+     * @return a year in cycle
+     */
+    private int getYearInCycle(int cycleNumber, long dayOfCycle) {
+        int[] cycles = getAdjustedCycle(cycleNumber);
+        if (dayOfCycle == 0) {
+            return 0;
+        }
+
+        if (dayOfCycle > 0) {
+            for (int i = 0; i < cycles.length; i++) {
+                if (dayOfCycle < cycles[i]) {
+                    return i - 1;
+                }
+            }
+            return 29;
+        } else {
+            dayOfCycle = -dayOfCycle;
+            for (int i = 0; i < cycles.length; i++) {
+                if (dayOfCycle <= cycles[i]) {
+                    return i - 1;
+                }
+            }
+            return 29;
+        }
+    }
+
+    /**
+     * Returns adjusted 30 year cycle starting day as Integer array from the
+     * cycle number specified.
+     *
+     * @param cycleNumber  a cycle number
+     * @return an Integer array
+     */
+    int[] getAdjustedCycle(int cycleNumber) {
+        int[] cycles;
+        try {
+            cycles = ADJUSTED_CYCLE_YEARS.get(cycleNumber);
+        } catch (ArrayIndexOutOfBoundsException e) {
+            cycles = null;
+        }
+        if (cycles == null) {
+            cycles = DEFAULT_CYCLE_YEARS;
+        }
+        return cycles;
+    }
+
+    /**
+     * Returns adjusted month days as Integer array form the year specified.
+     *
+     * @param year  a year
+     * @return an Integer array
+     */
+    int[] getAdjustedMonthDays(int year) {
+        int[] newMonths;
+        try {
+            newMonths = ADJUSTED_MONTH_DAYS.get(year);
+        } catch (ArrayIndexOutOfBoundsException e) {
+            newMonths = null;
+        }
+        if (newMonths == null) {
+            if (isLeapYear0(year)) {
+                newMonths = DEFAULT_LEAP_MONTH_DAYS;
+            } else {
+                newMonths = DEFAULT_MONTH_DAYS;
+            }
+        }
+        return newMonths;
+    }
+
+    /**
+     * Returns adjusted month length as Integer array form the year specified.
+     *
+     * @param year  a year
+     * @return an Integer array
+     */
+    int[] getAdjustedMonthLength(int year) {
+        int[] newMonths;
+        try {
+            newMonths = ADJUSTED_MONTH_LENGTHS.get(year);
+        } catch (ArrayIndexOutOfBoundsException e) {
+            newMonths = null;
+        }
+        if (newMonths == null) {
+            if (isLeapYear0(year)) {
+                newMonths = DEFAULT_LEAP_MONTH_LENGTHS;
+            } else {
+                newMonths = DEFAULT_MONTH_LENGTHS;
+            }
+        }
+        return newMonths;
+    }
+
+    /**
+     * Returns day-of-year.
+     *
+     * @param cycleNumber  a cycle number
+     * @param dayOfCycle  day of cycle
+     * @param yearInCycle  year in cycle
+     * @return day-of-year
+     */
+    private int getDayOfYear(int cycleNumber, int dayOfCycle, int yearInCycle) {
+        int[] cycles = getAdjustedCycle(cycleNumber);
+
+        if (dayOfCycle > 0) {
+            return dayOfCycle - cycles[yearInCycle];
+        } else {
+            return cycles[yearInCycle] + dayOfCycle;
+        }
+    }
+
+    /**
+     * Returns month-of-year. 0-based.
+     *
+     * @param dayOfYear  day-of-year
+     * @param year  a year
+     * @return month-of-year
+     */
+    private int getMonthOfYear(int dayOfYear, int year) {
+
+        int[] newMonths = getAdjustedMonthDays(year);
+
+        if (dayOfYear >= 0) {
+            for (int i = 0; i < newMonths.length; i++) {
+                if (dayOfYear < newMonths[i]) {
+                    return i - 1;
+                }
+            }
+            return 11;
+        } else {
+            dayOfYear = (isLeapYear0(year) ? (dayOfYear + 355)
+                    : (dayOfYear + 354));
+            for (int i = 0; i < newMonths.length; i++) {
+                if (dayOfYear < newMonths[i]) {
+                    return i - 1;
+                }
+            }
+            return 11;
+        }
+    }
+
+    /**
+     * Returns day-of-month.
+     *
+     * @param dayOfYear  day of  year
+     * @param month  month
+     * @param year  year
+     * @return day-of-month
+     */
+    private int getDayOfMonth(int dayOfYear, int month, int year) {
+
+        int[] newMonths = getAdjustedMonthDays(year);
+
+        if (dayOfYear >= 0) {
+            if (month > 0) {
+                return dayOfYear - newMonths[month];
+            } else {
+                return dayOfYear;
+            }
+        } else {
+            dayOfYear = (isLeapYear0(year) ? (dayOfYear + 355)
+                    : (dayOfYear + 354));
+            if (month > 0) {
+                return dayOfYear - newMonths[month];
+            } else {
+                return dayOfYear;
+            }
+        }
+    }
+
+
+    /**
+     * Returns month days from the beginning of year.
+     *
+     * @param month  month (0-based)
+     * @parma year  year
+     * @return month days from the beginning of year
+     */
+    private int getMonthDays(int month, int year) {
+        int[] newMonths = getAdjustedMonthDays(year);
+        return newMonths[month];
+    }
+
+    /**
+     * Returns month length.
+     *
+     * @param month  month (0-based)
+     * @param year  year
+     * @return month length
+     */
+    private int getMonthLength(int month, int year) {
+      int[] newMonths = getAdjustedMonthLength(year);
+      return newMonths[month];
+    }
+
+    /**
+     * Returns year length.
+     *
+     * @param year  year
+     * @return year length
+     */
+    int getYearLength(int year) {
+
+        int cycleNumber = (year - 1) / 30;
+        int[] cycleYears;
+        try {
+            cycleYears = ADJUSTED_CYCLE_YEARS.get(cycleNumber);
+        } catch (ArrayIndexOutOfBoundsException e) {
+            cycleYears = null;
+        }
+        if (cycleYears != null) {
+            int yearInCycle = (year - 1) % 30;
+            if (yearInCycle == 29) {
+                return (int)(ADJUSTED_CYCLES[cycleNumber + 1]
+                        - ADJUSTED_CYCLES[cycleNumber]
+                        - cycleYears[yearInCycle]);
+            }
+            return cycleYears[yearInCycle + 1]
+                    - cycleYears[yearInCycle];
+        } else {
+            return isLeapYear0(year) ? 355 : 354;
+        }
+    }
+
+
+    /**
+     * Returns maximum day-of-month.
+     *
+     * @return maximum day-of-month
+     */
+    int getMaximumDayOfMonth() {
+        return ADJUSTED_MAX_VALUES[POSITION_DAY_OF_MONTH];
+    }
+
+    /**
+     * Returns smallest maximum day-of-month.
+     *
+     * @return smallest maximum day-of-month
+     */
+    int getSmallestMaximumDayOfMonth() {
+        return ADJUSTED_LEAST_MAX_VALUES[POSITION_DAY_OF_MONTH];
+    }
+
+    /**
+     * Returns maximum day-of-year.
+     *
+     * @return maximum day-of-year
+     */
+    int getMaximumDayOfYear() {
+        return ADJUSTED_MAX_VALUES[POSITION_DAY_OF_YEAR];
+    }
+
+    /**
+     * Returns smallest maximum day-of-year.
+     *
+     * @return smallest maximum day-of-year
+     */
+    int getSmallestMaximumDayOfYear() {
+        return ADJUSTED_LEAST_MAX_VALUES[POSITION_DAY_OF_YEAR];
+    }
+
+    // ----- Deviation handling -----//
+
+    /**
+     * Adds deviation definition. The year and month specified should be the
+     * calculated Hijrah year and month. The month is 1 based. e.g. 9 for
+     * Ramadan (9th month) Addition of anything minus deviation days is
+     * calculated negatively in the case the user wants to subtract days from
+     * the calendar. For example, adding -1 days will subtract one day from the
+     * current date.
+     *
+     * @param startYear  start year, 1 origin
+     * @param startMonth  start month, 1 origin
+     * @param endYear  end year, 1 origin
+     * @param endMonth  end month, 1 origin
+     * @param offset  offset -2, -1, +1, +2
+     */
+    private void addDeviationAsHijrah(Deviation entry) {
+        int startYear = entry.startYear;
+        int startMonth = entry.startMonth - 1 ;
+        int endYear = entry.endYear;
+        int endMonth = entry.endMonth - 1;
+        int offset = entry.offset;
+
+        if (startYear < 1) {
+            throw new IllegalArgumentException("startYear < 1");
+        }
+        if (endYear < 1) {
+            throw new IllegalArgumentException("endYear < 1");
+        }
+        if (startMonth < 0 || startMonth > 11) {
+            throw new IllegalArgumentException(
+                    "startMonth < 0 || startMonth > 11");
+        }
+        if (endMonth < 0 || endMonth > 11) {
+            throw new IllegalArgumentException("endMonth < 0 || endMonth > 11");
+        }
+        if (endYear > 9999) {
+            throw new IllegalArgumentException("endYear > 9999");
+        }
+        if (endYear < startYear) {
+            throw new IllegalArgumentException("startYear > endYear");
+        }
+        if (endYear == startYear && endMonth < startMonth) {
+            throw new IllegalArgumentException(
+                    "startYear == endYear && endMonth < startMonth");
+        }
+
+        // Adjusting start year.
+        boolean isStartYLeap = isLeapYear0(startYear);
+
+        // Adjusting the number of month.
+        int[] orgStartMonthNums = ADJUSTED_MONTH_DAYS.get(startYear);
+        if (orgStartMonthNums == null) {
+            if (isStartYLeap) {
+                orgStartMonthNums = Arrays.copyOf(LEAP_NUM_DAYS, LEAP_NUM_DAYS.length);
+            } else {
+                orgStartMonthNums = Arrays.copyOf(NUM_DAYS, NUM_DAYS.length);
+            }
+        }
+
+        int[] newStartMonthNums = new int[orgStartMonthNums.length];
+
+        for (int month = 0; month < 12; month++) {
+            if (month > startMonth) {
+                newStartMonthNums[month] = (orgStartMonthNums[month] - offset);
+            } else {
+                newStartMonthNums[month] = (orgStartMonthNums[month]);
+            }
+        }
+
+        ADJUSTED_MONTH_DAYS.put(startYear, newStartMonthNums);
+
+        // Adjusting the days of month.
+
+        int[] orgStartMonthLengths = ADJUSTED_MONTH_LENGTHS.get(startYear);
+        if (orgStartMonthLengths == null) {
+            if (isStartYLeap) {
+                orgStartMonthLengths = Arrays.copyOf(LEAP_MONTH_LENGTH, LEAP_MONTH_LENGTH.length);
+            } else {
+                orgStartMonthLengths = Arrays.copyOf(MONTH_LENGTH, MONTH_LENGTH.length);
+            }
+        }
+
+        int[] newStartMonthLengths = new int[orgStartMonthLengths.length];
+
+        for (int month = 0; month < 12; month++) {
+            if (month == startMonth) {
+                newStartMonthLengths[month] = orgStartMonthLengths[month] - offset;
+            } else {
+                newStartMonthLengths[month] = orgStartMonthLengths[month];
+            }
+        }
+
+        ADJUSTED_MONTH_LENGTHS.put(startYear, newStartMonthLengths);
+
+        if (startYear != endYear) {
+            // System.out.println("over year");
+            // Adjusting starting 30 year cycle.
+            int sCycleNumber = (startYear - 1) / 30;
+            int sYearInCycle = (startYear - 1) % 30; // 0-based.
+            int[] startCycles = ADJUSTED_CYCLE_YEARS.get(sCycleNumber);
+            if (startCycles == null) {
+                startCycles = Arrays.copyOf(CYCLEYEAR_START_DATE, CYCLEYEAR_START_DATE.length);
+            }
+
+            for (int j = sYearInCycle + 1; j < CYCLEYEAR_START_DATE.length; j++) {
+                startCycles[j] = startCycles[j] - offset;
+            }
+
+            // System.out.println(sCycleNumber + ":" + sYearInCycle);
+            ADJUSTED_CYCLE_YEARS.put(sCycleNumber, startCycles);
+
+            int sYearInMaxY = (startYear - 1) / 30;
+            int sEndInMaxY = (endYear - 1) / 30;
+
+            if (sYearInMaxY != sEndInMaxY) {
+                // System.out.println("over 30");
+                // Adjusting starting 30 * MAX_ADJUSTED_CYCLE year cycle.
+                // System.out.println(sYearInMaxY);
+
+                for (int j = sYearInMaxY + 1; j < ADJUSTED_CYCLES.length; j++) {
+                    ADJUSTED_CYCLES[j] = ADJUSTED_CYCLES[j] - offset;
+                }
+
+                // Adjusting ending 30 * MAX_ADJUSTED_CYCLE year cycles.
+                for (int j = sEndInMaxY + 1; j < ADJUSTED_CYCLES.length; j++) {
+                    ADJUSTED_CYCLES[j] = ADJUSTED_CYCLES[j] + offset;
+                }
+            }
+
+            // Adjusting ending 30 year cycle.
+            int eCycleNumber = (endYear - 1) / 30;
+            int sEndInCycle = (endYear - 1) % 30; // 0-based.
+            int[] endCycles = ADJUSTED_CYCLE_YEARS.get(eCycleNumber);
+            if (endCycles == null) {
+                endCycles = Arrays.copyOf(CYCLEYEAR_START_DATE, CYCLEYEAR_START_DATE.length);
+            }
+            for (int j = sEndInCycle + 1; j < CYCLEYEAR_START_DATE.length; j++) {
+                endCycles[j] = endCycles[j] + offset;
+            }
+            ADJUSTED_CYCLE_YEARS.put(eCycleNumber, endCycles);
+        }
+
+        // Adjusting ending year.
+        boolean isEndYLeap = isLeapYear0(endYear);
+
+        int[] orgEndMonthDays = ADJUSTED_MONTH_DAYS.get(endYear);
+
+        if (orgEndMonthDays == null) {
+            if (isEndYLeap) {
+                orgEndMonthDays = Arrays.copyOf(LEAP_NUM_DAYS, LEAP_NUM_DAYS.length);
+            } else {
+                orgEndMonthDays = Arrays.copyOf(NUM_DAYS, NUM_DAYS.length);
+            }
+        }
+
+        int[] newEndMonthDays = new int[orgEndMonthDays.length];
+
+        for (int month = 0; month < 12; month++) {
+            if (month > endMonth) {
+                newEndMonthDays[month] = orgEndMonthDays[month] + offset;
+            } else {
+                newEndMonthDays[month] = orgEndMonthDays[month];
+            }
+        }
+
+        ADJUSTED_MONTH_DAYS.put(endYear, newEndMonthDays);
+
+        // Adjusting the days of month.
+        int[] orgEndMonthLengths = ADJUSTED_MONTH_LENGTHS.get(endYear);
+
+        if (orgEndMonthLengths == null) {
+            if (isEndYLeap) {
+                orgEndMonthLengths = Arrays.copyOf(LEAP_MONTH_LENGTH, LEAP_MONTH_LENGTH.length);
+            } else {
+                orgEndMonthLengths = Arrays.copyOf(MONTH_LENGTH, MONTH_LENGTH.length);
+            }
+        }
+
+        int[] newEndMonthLengths = new int[orgEndMonthLengths.length];
+
+        for (int month = 0; month < 12; month++) {
+            if (month == endMonth) {
+                newEndMonthLengths[month] = orgEndMonthLengths[month] + offset;
+            } else {
+                newEndMonthLengths[month] = orgEndMonthLengths[month];
+            }
+        }
+
+        ADJUSTED_MONTH_LENGTHS.put(endYear, newEndMonthLengths);
+
+        int[] startMonthLengths = ADJUSTED_MONTH_LENGTHS.get(startYear);
+        int[] endMonthLengths = ADJUSTED_MONTH_LENGTHS.get(endYear);
+        int[] startMonthDays = ADJUSTED_MONTH_DAYS.get(startYear);
+        int[] endMonthDays = ADJUSTED_MONTH_DAYS.get(endYear);
+
+        int startMonthLength = startMonthLengths[startMonth];
+        int endMonthLength = endMonthLengths[endMonth];
+        int startMonthDay = startMonthDays[11] + startMonthLengths[11];
+        int endMonthDay = endMonthDays[11] + endMonthLengths[11];
+
+        int maxMonthLength = ADJUSTED_MAX_VALUES[POSITION_DAY_OF_MONTH];
+        int leastMaxMonthLength = ADJUSTED_LEAST_MAX_VALUES[POSITION_DAY_OF_MONTH];
+
+        if (maxMonthLength < startMonthLength) {
+            maxMonthLength = startMonthLength;
+        }
+        if (maxMonthLength < endMonthLength) {
+            maxMonthLength = endMonthLength;
+        }
+        ADJUSTED_MAX_VALUES[POSITION_DAY_OF_MONTH] = maxMonthLength;
+
+        if (leastMaxMonthLength > startMonthLength) {
+            leastMaxMonthLength = startMonthLength;
+        }
+        if (leastMaxMonthLength > endMonthLength) {
+            leastMaxMonthLength = endMonthLength;
+        }
+        ADJUSTED_LEAST_MAX_VALUES[POSITION_DAY_OF_MONTH] = leastMaxMonthLength;
+
+        int maxMonthDay = ADJUSTED_MAX_VALUES[POSITION_DAY_OF_YEAR];
+        int leastMaxMonthDay = ADJUSTED_LEAST_MAX_VALUES[POSITION_DAY_OF_YEAR];
+
+        if (maxMonthDay < startMonthDay) {
+            maxMonthDay = startMonthDay;
+        }
+        if (maxMonthDay < endMonthDay) {
+            maxMonthDay = endMonthDay;
+        }
+
+        ADJUSTED_MAX_VALUES[POSITION_DAY_OF_YEAR] = maxMonthDay;
+
+        if (leastMaxMonthDay > startMonthDay) {
+            leastMaxMonthDay = startMonthDay;
+        }
+        if (leastMaxMonthDay > endMonthDay) {
+            leastMaxMonthDay = endMonthDay;
+        }
+        ADJUSTED_LEAST_MAX_VALUES[POSITION_DAY_OF_YEAR] = leastMaxMonthDay;
+    }
+
+    /**
+     * Package private Entry for suppling deviations from the Reader.
+     * Each entry consists of a range using the Hijrah calendar,
+     * start year, month, end year, end month, and an offset.
+     * The offset is used to modify the length of the month +2, +1, -1, -2.
+     */
+    static final class Deviation {
+
+        Deviation(int startYear, int startMonth, int endYear, int endMonth, int offset) {
+            this.startYear = startYear;
+            this.startMonth = startMonth;
+            this.endYear = endYear;
+            this.endMonth = endMonth;
+            this.offset = offset;
+        }
+
+        final int startYear;
+        final int startMonth;
+        final int endYear;
+        final int endMonth;
+        final int offset;
+
+        int getStartYear() {
+            return startYear;
+        }
+
+        int getStartMonth() {
+            return startMonth;
+        }
+
+        int getEndYear() {
+            return endYear;
+        }
+
+        int getEndMonth() {
+            return endMonth;
+        }
+
+        int getOffset() {
+            return offset;
+        }
+
+        @Override
+        public String toString() {
+            return String.format("[year: %4d, month: %2d, offset: %+d]", startYear, startMonth, offset);
+        }
+    }
+
+}