ealet
Class Calendar

java.lang.Object
  ealet.Calendar

public class Calendar
extends java.lang.Object

Ethiopian calendar generator including monthly, annual, and moving holidays. It is limited to CE (Common Era); that is, from 00. The calendar calculation, religious and national holidays system is based on Dr. Getatchew Haile's book "Bahra Hassab" published in 2000.

This class can be used for these specific tasks.

• To generate annual Ethioian calendar
  
  

            Calendar cal = new Calendar(year) ;
         

• To convert from Ethiopian date to Gregorian
  
  

            Day day = Calendar.toGregorian(month, date, year) ;
         

• To convert from Gregorian date to Ethiopian
  
  

            Day day = Calendar.toEthiopian(month, date, year) ;
         

Each calendar is generated and organized in a set of linked-list data structure. The following crude figure shows how that structure looks like.

             ---------   ---------   ---------
    Year     |  Sep  |---|  Oct  |---|  Nov  |--- ...
             ---------   ---------   ---------
                 +           +           +
                 |           |           |
                 |           |           |
             ---------   ---------   ---------   -------------
    Day     |  Mon   |   |  Tue  |   |  Thu  |---|  holiday  |....
             ---------   ---------   ---------   -------------
                 .           .           .
                 .           .           .
                 .           .           .
 

Some important terms:

• abekitee refers to the difference or overlapping days between Lunar and Solar calendar. Lunar's calendar year is shorter than Solar's by 11 days and this number increases every year. The Ethiopian Orthodox Church calculates its some of fasting holidays based on lunar calendar year. In the process, when the difference reaches over the 30 days, it is modulated by 30 and the result is used.
• metqee is the number of days it takes for Lunar month to complete when it is overlapped with the beginning month of new year. metiqee is calculate by subtracting abekitte from 30. If the result is equal or less than to 8, metqee is said to occur in October; otherwise, in September
• Tintyon is a system by which one can determine the first day of each month if one is known. For instance, if the 1st day of September is Monday, April's 1st day will occur Monday and January's on Tuesday.
• CE (Common Era) is used in place of AD (anno Domini)
• BCE (Before Common Era) is used in place of BC (before Christ)

Constructor Summary

Calendar(int year)
Constructor: A linked-list for months is constructed.

Method Summary

static java.lang.String	getDay(int month, int date, int ce) Returns the day of the given date.
static int	getEthiopianDayIndex(int month, int date, int year) Determines what the day is for a given Ethiopian date.
java.util.LinkedList[]	getEthiopianGregorianCalendar() This method generates the calendar for the requested year.
java.lang.String	getGregorianDay(int ce, int month, int date) Returns the day of a given Gregorian date
int	getMetqee(int ce) Returns the metqee for the given year
java.lang.String	getNewYearDay(int ce) Returns the Ethiopian new year day which will be used as starting day for the given year
void	insertAnnualHoliday() The method prepares annual holidays with integer array.
void	insertMonthlyHoliday() It prepares monthly holidays with integer array.
void	insertMovingHolidays() Fasting holidays are variables since they are calcualted based on moon's epect.
static Day	toEthiopian(int month, int date, int year) The method performs conversion from Gregorian date to Ethiopian.
static Day	toGregorian(int month, int date, int year) The method performs conversion from Ethiopian date to Gregorian.
static int	whenIsEthNewYearInGregSeptember(int year) Ethiopian new year occurs either on Gregorian September 11/12.

Methods inherited from class java.lang.Object

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

Constructor Detail

Calendar

public Calendar(int year)

Constructor: A linked-list for months is constructed. *

Parameters:

year - the year to which a calendar will be built

Method Detail

getMetqee

public int getMetqee(int ce)

Returns the metqee for the given year

Parameters:

ce - a year for which metqee is generated

Returns:

metiqee is equal to 30 - abekitee

Since:

2.0

getNewYearDay

public java.lang.String getNewYearDay(int ce)

Returns the Ethiopian new year day which will be used as starting day for the given year

Parameters:

ce - A year for which metqee is generated

Returns:

The name of the first day in String form

Since:

2.0

getDay

public static java.lang.String getDay(int month,
                                      int date,
                                      int ce)

Returns the day of the given date. It starts counting from Tuesday of BCE era 1st day to arrive to the right one.

Parameters:

month - Ethiopian month

date - Ethiopian date

ce - Ethiopian Common Era year

Returns:

The day of the given date in String form

Since:

2.0

insertMonthlyHoliday

public void insertMonthlyHoliday()

It prepares monthly holidays with integer array. It fetches each Day instance and adds the monthly holidays to its list. These holidays will be mapped to proper names by the XMLer class during transformation. For that purpose, the XMLer class utilizes a properties file.

The properties file is "ealet_holiday_properties.xml" and has the following form.

The key and values ares

     1         abo
     ^          ^
    key       value
     ^          ^
     |          |
     |           ----- the name of the holiday
     | 
      ----- the date of the month to the holiday belongs
 

Since:

2.0

insertAnnualHoliday

public void insertAnnualHoliday()

The method prepares annual holidays with integer array. It fetches each Day instance from the calendar and inserts these holidays. The month and date where each annual holiday occurs is used in combination as a key in the holiday properties file and used by the XMLer class during transformation to retrieve the holiday names.

The properties file is "ealet_holiday_properties.xml" and has the following field and value content.

The key and values ares

    1-1     Enkutatash
     ^          ^
    key       value
     ^          ^
     |          |
     |           ----- the name of the holiday
     | 
      ----- the 1st is month while the 2nd is date
 

Since:

2.0

insertMovingHolidays

public void insertMovingHolidays()

Fasting holidays are variables since they are calcualted based on moon's epect. The 1st fasting holiday is Nenewei and it is calculated using metiqee and tewissak. The remaining fasting holidays can be determined based on Nenewei since their ranges are known.

As each fasting holiday is calculated, an instance of the Day class is created and inserted into the calendar under each proper month and date. This method must be called after the main calendar is built; that is. after the calendarYear linked list is completely built. Failing to do so will result fatal error.

Since:

2.0

getGregorianDay

public java.lang.String getGregorianDay(int ce,
                                        int month,
                                        int date)

Returns the day of a given Gregorian date

Parameters:

month - Gregorian calendar month

date - Gregorian calendar date

ce - Gregorian calendar year

Returns:

The name of the day on the given Gregorian date

Since:

2.0

whenIsEthNewYearInGregSeptember

public static int whenIsEthNewYearInGregSeptember(int year)

Ethiopian new year occurs either on Gregorian September 11/12. If the year preceeding the new year is a leap year, Paguemain will have 6 days; therefore, Ethiopian new year occurs on Gregorian September 12. This method determines when new year occurs on Gregorian September.

Parameters:

year - Ethiopian year

Returns:

The date of September when Ethiopian new year occurs

Since:

2.0

toGregorian

public static Day toGregorian(int month,
                              int date,
                              int year)

The method performs conversion from Ethiopian date to Gregorian. Breifely,

• Determines when Ethiopian new years occurs in Greg. September
• Initially, converts Eth year to Greg using the 7 years diff
• If Eth date falls after Dec, the Greg year must be up by 1 year
• Since the Eth new year is on September, its overlaps with Gregorian; thus to calculate the Greg month an order is introduced
• Once the Greg date is found, the day is easily obtained

Parameters:

month - Ethiopian calendar month

date - Ethiopian calendar date

year - Ethiopian calendar year

Returns:

Ethiopian day

toEthiopian

public static Day toEthiopian(int month,
                              int date,
                              int year)

The method performs conversion from Gregorian date to Ethiopian. Breifely,

• Determines when Ethiopian new years occurs in Greg. September
• Initially, converts Greg year to Eth using the 8 years diff
• If Greg date falls after Sept 10/11, the Eth year must be up by 1 year
• Since the Eth new year is on September, its overlaps with Gregorian; thus to calculate the Greg month an order is introduced
• The Eth month and date are determined

Parameters:

month - Gregorian calendar month

date - Gregorian calendar date

year - Gregorian calendar year

Returns:

Gregorian day

getEthiopianDayIndex

public static int getEthiopianDayIndex(int month,
                                       int date,
                                       int year)

Determines what the day is for a given Ethiopian date. It starts counting from 5500, the number of years in BCE, continuing the BC years. The 1st day starts with "Tuesday".

Parameters:

month - Ethiopian month

date - Ethiopian date

year - Ethiopian year

Returns:

Ethiopian day

getEthiopianGregorianCalendar

public java.util.LinkedList[] getEthiopianGregorianCalendar()

This method generates the calendar for the requested year. It involves a serious of steps.

• Determins the 1st day of both the Eth and Greg year
• Generates the equivalent Greg year for Eth
• If Greg leap year, March will have 29 days
• Using linked list for months and days, calendar is built
• Updates the calendar by adding holidays, and fasting holidays

Finally, it returns an array of a linked list consisting of the calendar.

Since:

2.0