Class JulianCalendar

java.lang.Object

org.episteme.social.history.calendars.AlternateCalendar

org.episteme.social.history.calendars.SevenDaysWeek

org.episteme.social.history.calendars.MonthDayYear

org.episteme.social.history.calendars.GregorianCalendar

org.episteme.social.history.calendars.JulianCalendar

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

CopticCalendar

public class JulianCalendar
extends GregorianCalendar

Implementation of the proleptic Julian calendar. The Julian calendar was introduced by Julius Caesar in 46 BCE and was the predominant calendar in the Roman world and subsequently in the Western world until the Gregorian reform of 1582.

Key differences from the Gregorian calendar:

• Leap year rule: every year divisible by 4 (no century exception)
• Drifts approximately 1 day per 128 years relative to the tropical year
• Uses astronomical year numbering (year 0 = 1 BCE)

* @version 2.0

Since:

1.0

Author:

Silvere Martin-Michiellot, Gemini AI (Google DeepMind)

See Also:

• Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
static long	EPOCH	The Julian epoch: December 30, 1 BCE (proleptic Gregorian) = January 1, 1 CE (Julian).

Fields inherited from class GregorianCalendar

MONTHS

Fields inherited from class MonthDayYear

day, month, year

Fields inherited from class SevenDaysWeek

DAY_NAMES, FRIDAY, MONDAY, SATURDAY, SUNDAY, THURSDAY, TUESDAY, WEDNESDAY

Fields inherited from class AlternateCalendar

JD_EPOCH, rd, unicode

Constructor Summary

Constructors

Constructor	Description
JulianCalendar()	Creates a Julian calendar set to the epoch (January 1, 1 CE).
JulianCalendar(int year, int month, int day)	Creates a Julian calendar set to the specified date.
JulianCalendar(long rataDie)	Creates a Julian calendar set to the specified Rata Die.
JulianCalendar(AlternateCalendar calendar)	Creates a Julian calendar from another calendar's date.

Method Summary

Modifier and Type	Method	Description
protected String	getSuffix()	Returns the era suffix for display.
static boolean	isLeapYear(int year)	Determines if the specified year is a leap year in the Julian calendar.
protected void	recomputeFromRD()	Recomputes the year, month, and day fields from the current Rata Die.
protected void	recomputeRD()	Recomputes the Rata Die from the current year, month, and day fields.
void	set(long rataDie)	Sets this calendar to the specified Rata Die and recomputes the date fields.
String	toString()	Returns a string representation of this date.

Methods inherited from class GregorianCalendar

dayNumber, daysLeft, getMonths, monthName

Methods inherited from class MonthDayYear

getDay, getMonth, getYear, set

Methods inherited from class SevenDaysWeek

kDayAfter, kDayBefore, kDayNearest, kDayOnOrAfter, kDayOnOrBefore, nthKDay, weekDay, weekDayName

Methods inherited from class AlternateCalendar

add, amod, difference, difference, floorDiv, fromJD, isAfter, isBefore, mod, mod, subtract, toJD, toJD, toRD

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Details

EPOCH

public static long EPOCH

The Julian epoch: December 30, 1 BCE (proleptic Gregorian) = January 1, 1 CE (Julian).

Constructor Details

JulianCalendar

public JulianCalendar(long rataDie)

Creates a Julian calendar set to the specified Rata Die.

Parameters:

rataDie - the day number

JulianCalendar

public JulianCalendar()

Creates a Julian calendar set to the epoch (January 1, 1 CE).

JulianCalendar

public JulianCalendar(AlternateCalendar calendar)

Creates a Julian calendar from another calendar's date.

Parameters:

calendar - the source calendar

JulianCalendar

public JulianCalendar(int year,
 int month,
 int day)

Creates a Julian calendar set to the specified date.

Parameters:

year - the year (negative for BCE, using astronomical year numbering)

month - the month (1-12)

day - the day of month (1-31)

Method Details

recomputeRD

protected void recomputeRD()

Recomputes the Rata Die from the current year, month, and day fields.

Overrides:

recomputeRD in class GregorianCalendar

recomputeFromRD

protected void recomputeFromRD()

Recomputes the year, month, and day fields from the current Rata Die.

Overrides:

recomputeFromRD in class GregorianCalendar

set

public void set(long rataDie)

Sets this calendar to the specified Rata Die and recomputes the date fields.

Overrides:

set in class GregorianCalendar

Parameters:

rataDie - the new Rata Die value

isLeapYear

public static boolean isLeapYear(int year)

Determines if the specified year is a leap year in the Julian calendar. In the Julian calendar, every year divisible by 4 is a leap year.

Parameters:

year - the year to check (using astronomical year numbering)

Returns:

true if it's a leap year

getSuffix

protected String getSuffix()

Returns the era suffix for display.

Overrides:

getSuffix in class GregorianCalendar

Returns:

" C.E." for positive years, " B.C.E." for non-positive years

toString

public String toString()

Returns a string representation of this date.

Overrides:

toString in class GregorianCalendar

Returns:

formatted date string