IndianCalendar is a subclass of GregorianCalendar
* that numbers years since the birth of the Buddha. This is the civil calendar
* which is accepted by government of India as Indian National Calendar.
* The two calendars most widely used in India today are the Vikrama calendar
* followed in North India and the Shalivahana or Saka calendar which is followed
* in South India and Maharashtra.
* A variant of the Shalivahana Calendar was reformed and standardized as the
* Indian National calendar in 1957.
* * Some details of Indian National Calendar (to be implemented) : * The Months * Month Length Start date (Gregorian) * ================================================= * 1 Chaitra 30/31 March 22* * 2 Vaisakha 31 April 21 * 3 Jyaistha 31 May 22 * 4 Asadha 31 June 22 * 5 Sravana 31 July 23 * 6 Bhadra 31 August 23 * 7 Asvina 30 September 23 * 8 Kartika 30 October 23 * 9 Agrahayana 30 November 22 * 10 Pausa 30 December 22 * 11 Magha 30 January 21 * 12 Phalguna 30 February 20 * In leap years, Chaitra has 31 days and starts on March 21 instead. * The leap years of Gregorian calendar and Indian National Calendar are in synchornization. * So When its a leap year in Gregorian calendar then Chaitra has 31 days. * * The Years * Years are counted in the Saka Era, which starts its year 0 in 78AD (by gregorian calendar). * So for eg. 9th June 2006 by Gregorian Calendar, is same as 19th of Jyaistha in 1928 of Saka * era by Indian National Calendar. *
* The Indian Calendar has only one allowable era: Saka Era. If the
* calendar is not in lenient mode (see setLenient), dates before
* 1/1/1 Saka Era are rejected with an IllegalArgumentException.
*
* This class should not be subclassed.
*
* IndianCalendar usually should be instantiated using
* {@link android.icu.util.Calendar#getInstance(ULocale)} passing in a ULocale
* with the tag "@calendar=Indian".
ERA
* value for the Indian calendar.
*
* @see android.icu.util.Calendar#ERA
*/
public static final int IE = 0;
/**
* Constructs a IndianCalendar using the current time
* in the default time zone with the default FORMAT locale.
* @see Category#FORMAT
*/
public IndianCalendar() {
this(TimeZone.getDefault(), ULocale.getDefault(Category.FORMAT));
}
/**
* Constructs a IndianCalendar based on the current time
* in the given time zone with the default FORMAT locale.
*
* @param zone the given time zone.
* @see Category#FORMAT
*/
public IndianCalendar(TimeZone zone) {
this(zone, ULocale.getDefault(Category.FORMAT));
}
/**
* Constructs a IndianCalendar based on the current time
* in the default time zone with the given locale.
*
* @param aLocale the given locale.
*/
public IndianCalendar(Locale aLocale) {
this(TimeZone.getDefault(), aLocale);
}
/**
* Constructs a IndianCalendar based on the current time
* in the default time zone with the given locale.
*
* @param locale the given ulocale.
*/
public IndianCalendar(ULocale locale) {
this(TimeZone.getDefault(), locale);
}
/**
* Constructs a IndianCalendar based on the current time
* in the given time zone with the given locale.
*
* @param zone the given time zone.
*
* @param aLocale the given locale.
*/
public IndianCalendar(TimeZone zone, Locale aLocale) {
super(zone, aLocale);
setTimeInMillis(System.currentTimeMillis());
}
/**
* Constructs a IndianCalendar based on the current time
* in the given time zone with the given locale.
*
* @param zone the given time zone.
*
* @param locale the given ulocale.
*/
public IndianCalendar(TimeZone zone, ULocale locale) {
super(zone, locale);
setTimeInMillis(System.currentTimeMillis());
}
/**
* Constructs a IndianCalendar with the given date set
* in the default time zone with the default FORMAT locale.
*
* @param date The date to which the new calendar is set.
* @see Category#FORMAT
*/
public IndianCalendar(Date date) {
super(TimeZone.getDefault(), ULocale.getDefault(Category.FORMAT));
this.setTime(date);
}
/**
* Constructs a IndianCalendar with the given date set
* in the default time zone with the default FORMAT locale.
*
* @param year The value used to set the calendar's {@link #YEAR YEAR} time field.
*
* @param month The value used to set the calendar's {@link #MONTH MONTH} time field.
* The value is 0-based. e.g., 0 for January.
*
* @param date The value used to set the calendar's {@link #DATE DATE} time field.
* @see Category#FORMAT
*/
public IndianCalendar(int year, int month, int date) {
super(TimeZone.getDefault(), ULocale.getDefault(Category.FORMAT));
this.set(Calendar.YEAR, year);
this.set(Calendar.MONTH, month);
this.set(Calendar.DATE, date);
}
/**
* Constructs a IndianCalendar with the given date
* and time set for the default time zone with the default FORMAT locale.
*
* @param year The value used to set the calendar's {@link #YEAR YEAR} time field.
*
* @param month The value used to set the calendar's {@link #MONTH MONTH} time field.
* The value is 0-based. e.g., 0 for January.
*
* @param date The value used to set the calendar's {@link #DATE DATE} time field.
*
* @param hour The value used to set the calendar's {@link #HOUR_OF_DAY HOUR_OF_DAY} time field.
*
* @param minute The value used to set the calendar's {@link #MINUTE MINUTE} time field.
*
* @param second The value used to set the calendar's {@link #SECOND SECOND} time field.
* @see Category#FORMAT
*/
public IndianCalendar(int year, int month, int date, int hour,
int minute, int second)
{
super(TimeZone.getDefault(), ULocale.getDefault(Category.FORMAT));
this.set(Calendar.YEAR, year);
this.set(Calendar.MONTH, month);
this.set(Calendar.DATE, date);
this.set(Calendar.HOUR_OF_DAY, hour);
this.set(Calendar.MINUTE, minute);
this.set(Calendar.SECOND, second);
}
//-------------------------------------------------------------------------
// The only practical difference from a Gregorian calendar is that years
// are numbered since the Saka Era. A couple of overrides will
// take care of that....
//-------------------------------------------------------------------------
// Starts in 78 AD,
private static final int INDIAN_ERA_START = 78;
// The Indian year starts 80 days later than the Gregorian year.
private static final int INDIAN_YEAR_START = 80;
/**
* {@inheritDoc}
*/
protected int handleGetExtendedYear() {
int year;
if (newerField(EXTENDED_YEAR, YEAR) == EXTENDED_YEAR) {
year = internalGet(EXTENDED_YEAR, 1);
} else {
// Ignore the era, as there is only one
year = internalGet(YEAR, 1);
}
return year;
}
/**
* {@inheritDoc}
*/
protected int handleGetYearLength(int extendedYear) {
return super.handleGetYearLength(extendedYear);
}
/**
* {@inheritDoc}
*/
protected int handleGetMonthLength(int extendedYear, int month) {
if (month < 0 || month > 11) {
int[] remainder = new int[1];
extendedYear += floorDivide(month, 12, remainder);
month = remainder[0];
}
if(isGregorianLeap(extendedYear + INDIAN_ERA_START) && month == 0) {
return 31;
}
if(month >= 1 && month <=5) {
return 31;
}
return 30;
}
/**
* {@inheritDoc}
*/
protected void handleComputeFields(int julianDay){
double jdAtStartOfGregYear;
int leapMonth, IndianYear, yday, IndianMonth, IndianDayOfMonth, mday;
int[] gregorianDay; // Stores gregorian date corresponding to Julian day;
gregorianDay = jdToGregorian(julianDay); // Gregorian date for Julian day
IndianYear = gregorianDay[0] - INDIAN_ERA_START; // Year in Saka era
jdAtStartOfGregYear = gregorianToJD(gregorianDay[0], 1, 1); // JD at start of Gregorian year
yday = (int)(julianDay - jdAtStartOfGregYear); // Day number in Gregorian year (starting from 0)
if (yday < INDIAN_YEAR_START) {
// Day is at the end of the preceding Saka year
IndianYear -= 1;
leapMonth = isGregorianLeap(gregorianDay[0] - 1) ? 31 : 30; // Days in leapMonth this year, previous Gregorian year
yday += leapMonth + (31 * 5) + (30 * 3) + 10;
} else {
leapMonth = isGregorianLeap(gregorianDay[0]) ? 31 : 30; // Days in leapMonth this year
yday -= INDIAN_YEAR_START;
}
if (yday < leapMonth) {
IndianMonth = 0;
IndianDayOfMonth = yday + 1;
} else {
mday = yday - leapMonth;
if (mday < (31 * 5)) {
IndianMonth = mday / 31 + 1;
IndianDayOfMonth = (mday % 31) + 1;
} else {
mday -= 31 * 5;
IndianMonth = mday / 30 + 6;
IndianDayOfMonth = (mday % 30) + 1;
}
}
internalSet(ERA, 0);
internalSet(EXTENDED_YEAR, IndianYear);
internalSet(YEAR, IndianYear);
internalSet(MONTH, IndianMonth);
internalSet(DAY_OF_MONTH, IndianDayOfMonth );
internalSet(DAY_OF_YEAR, yday + 1); // yday is 0-based
}
private static final int LIMITS[][] = {
// Minimum Greatest Least Maximum
// Minimum Maximum
{ 0, 0, 0, 0}, // ERA
{ -5000000, -5000000, 5000000, 5000000}, // YEAR
{ 0, 0, 11, 11}, // MONTH
{ 1, 1, 52, 53}, // WEEK_OF_YEAR
{/* */}, // WEEK_OF_MONTH
{ 1, 1, 30, 31}, // DAY_OF_MONTH
{ 1, 1, 365, 366}, // DAY_OF_YEAR
{/* */}, // DAY_OF_WEEK
{ -1, -1, 5, 5}, // DAY_OF_WEEK_IN_MONTH
{/* */}, // AM_PM
{/* */}, // HOUR
{/* */}, // HOUR_OF_DAY
{/* */}, // MINUTE
{/* */}, // SECOND
{/* */}, // MILLISECOND
{/* */}, // ZONE_OFFSET
{/* */}, // DST_OFFSET
{ -5000000, -5000000, 5000000, 5000000}, // YEAR_WOY
{/* */}, // DOW_LOCAL
{ -5000000, -5000000, 5000000, 5000000}, // EXTENDED_YEAR
{/* */}, // JULIAN_DAY
{/* */}, // MILLISECONDS_IN_DAY
};
/**
* {@inheritDoc}
*/
protected int handleGetLimit(int field, int limitType) {
return LIMITS[field][limitType];
}
/**
* {@inheritDoc}
*/
protected int handleComputeMonthStart(int year, int month, boolean useMonth) {
//month is 0 based; converting it to 1-based
int imonth;
// If the month is out of range, adjust it into range, and adjust the extended year accordingly
if (month < 0 || month > 11) {
year += month / 12;
month %= 12;
}
if(month == 12) {
imonth = 1;
} else {
imonth = month +1;
}
double jd = IndianToJD(year ,imonth, 1);
return (int)jd;
}
/*
* This routine converts an Indian date to the corresponding Julian date"
* @param year The year in Saka Era according to Indian calendar.
* @param month The month according to Indian calendar (between 1 to 12)
* @param date The date in month
*/
private static double IndianToJD(int year, int month, int date) {
int leapMonth, gyear, m;
double start, jd;
gyear = year + INDIAN_ERA_START;
if(isGregorianLeap(gyear)) {
leapMonth = 31;
start = gregorianToJD(gyear, 3, 21);
} else {
leapMonth = 30;
start = gregorianToJD(gyear, 3, 22);
}
if (month == 1) {
jd = start + (date - 1);
} else {
jd = start + leapMonth;
m = month - 2;
m = Math.min(m, 5);
jd += m * 31;
if (month >= 8) {
m = month - 7;
jd += m * 30;
}
jd += date - 1;
}
return jd;
}
/*
* The following function is not needed for basic calendar functioning.
* This routine converts a gregorian date to the corresponding Julian date"
* @param year The year in standard Gregorian calendar (AD/BC) .
* @param month The month according to Gregorian calendar (between 0 to 11)
* @param date The date in month
*/
private static double gregorianToJD(int year, int month, int date) {
double JULIAN_EPOCH = 1721425.5;
int y = year - 1;
int result = (365 * y)
+ (y / 4)
- (y / 100)
+ (y / 400)
+ (((367 * month) - 362) / 12)
+ ((month <= 2) ? 0 : (isGregorianLeap(year) ? -1 : -2))
+ date;
return result - 1 + JULIAN_EPOCH;
}
/*
* The following function is not needed for basic calendar functioning.
* This routine converts a julian day (jd) to the corresponding date in Gregorian calendar"
* @param jd The Julian date in Julian Calendar which is to be converted to Indian date"
*/
private static int[] jdToGregorian(double jd) {
double JULIAN_EPOCH = 1721425.5;
double wjd, depoch, quadricent, dqc, cent, dcent, quad, dquad, yindex, yearday, leapadj;
int year, month, day;
wjd = Math.floor(jd - 0.5) + 0.5;
depoch = wjd - JULIAN_EPOCH;
quadricent = Math.floor(depoch / 146097);
dqc = depoch % 146097;
cent = Math.floor(dqc / 36524);
dcent = dqc % 36524;
quad = Math.floor(dcent / 1461);
dquad = dcent % 1461;
yindex = Math.floor(dquad / 365);
year = (int)((quadricent * 400) + (cent * 100) + (quad * 4) + yindex);
if (!((cent == 4) || (yindex == 4))) {
year++;
}
yearday = wjd - gregorianToJD(year, 1, 1);
leapadj = ((wjd < gregorianToJD(year, 3, 1)) ? 0
:
(isGregorianLeap(year) ? 1 : 2)
);
month = (int)Math.floor((((yearday + leapadj) * 12) + 373) / 367);
day = (int)(wjd - gregorianToJD(year, month, 1)) + 1;
int[] julianDate = new int[3];
julianDate[0] = year;
julianDate[1] = month;
julianDate[2] = day;
return julianDate;
}
/*
* The following function is not needed for basic calendar functioning.
* This routine checks if the Gregorian year is a leap year"
* @param year The year in Gregorian Calendar
*/
private static boolean isGregorianLeap(int year)
{
return ((year % 4) == 0) &&
(!(((year % 100) == 0) && ((year % 400) != 0)));
}
/**
* {@inheritDoc}
*/
public String getType() {
return "indian";
}
}