com.ibm.icu.util
Class ChineseCalendar

java.lang.Object
  extended by com.ibm.icu.util.Calendar
      extended by com.ibm.icu.util.ChineseCalendar
All Implemented Interfaces:
Serializable, Cloneable, Comparable

public class ChineseCalendar
extends Calendar

ChineseCalendar is a concrete subclass of Calendar that implements a traditional Chinese calendar. The traditional Chinese calendar is a lunisolar calendar: Each month starts on a new moon, and the months are numbered according to solar events, specifically, to guarantee that month 11 always contains the winter solstice. In order to accomplish this, leap months are inserted in certain years. Leap months are numbered the same as the month they follow. The decision of which month is a leap month depends on the relative movements of the sun and moon.

This class defines one addition field beyond those defined by Calendar: The IS_LEAP_MONTH field takes the value of 0 for normal months, or 1 for leap months.

All astronomical computations are performed with respect to a time zone of GMT+8:00 and a longitude of 120 degrees east. Although some calendars implement a historically more accurate convention of using Beijing's local longitude (116 degrees 25 minutes east) and time zone (GMT+7:45:40) for dates before 1929, we do not implement this here.

Years are counted in two different ways in the Chinese calendar. The first method is by sequential numbering from the 61st year of the reign of Huang Di, 2637 BCE, which is designated year 1 on the Chinese calendar. The second method uses 60-year cycles from the same starting point, which is designated year 1 of cycle 1. In this class, the EXTENDED_YEAR field contains the sequential year count. The ERA field contains the cycle number, and the YEAR field contains the year of the cycle, a value between 1 and 60.

There is some variation in what is considered the starting point of the calendar, with some sources starting in the first year of the reign of Huang Di, rather than the 61st. This gives continuous year numbers 60 years greater and cycle numbers one greater than what this class implements.

Because ChineseCalendar defines an additional field and redefines the way the ERA field is used, it requires a new format class, ChineseDateFormat. As always, use the methods DateFormat.getXxxInstance(Calendar cal,...) to obtain a formatter for this calendar.

References:

This class should not be subclassed.

ChineseCalendar usually should be instantiated using Calendar.getInstance(ULocale) passing in a ULocale with the tag "@calendar=chinese".

Author:
Alan Liu
See Also:
ChineseDateFormat, Calendar, Serialized Form

Field Summary
static int IS_LEAP_MONTH
          Field indicating whether or not the current month is a leap month.
 
Fields inherited from class com.ibm.icu.util.Calendar
AM, AM_PM, APRIL, AUGUST, BASE_FIELD_COUNT, DATE, DAY_OF_MONTH, DAY_OF_WEEK, DAY_OF_WEEK_IN_MONTH, DAY_OF_YEAR, DECEMBER, DOW_LOCAL, DST_OFFSET, EPOCH_JULIAN_DAY, ERA, EXTENDED_YEAR, FEBRUARY, FRIDAY, GREATEST_MINIMUM, HOUR, HOUR_OF_DAY, INTERNALLY_SET, JAN_1_1_JULIAN_DAY, JANUARY, JULIAN_DAY, JULY, JUNE, LEAST_MAXIMUM, MARCH, MAX_DATE, MAX_FIELD_COUNT, MAX_JULIAN, MAX_MILLIS, MAXIMUM, MAY, MILLISECOND, MILLISECONDS_IN_DAY, MIN_DATE, MIN_JULIAN, MIN_MILLIS, MINIMUM, MINIMUM_USER_STAMP, MINUTE, MONDAY, MONTH, NOVEMBER, OCTOBER, ONE_DAY, ONE_HOUR, ONE_MINUTE, ONE_SECOND, ONE_WEEK, PM, RESOLVE_REMAP, SATURDAY, SECOND, SEPTEMBER, SUNDAY, THURSDAY, TUESDAY, UNDECIMBER, UNSET, WEDNESDAY, WEEK_OF_MONTH, WEEK_OF_YEAR, WEEKDAY, WEEKEND, WEEKEND_CEASE, WEEKEND_ONSET, YEAR, YEAR_WOY, ZONE_OFFSET
 
Constructor Summary
ChineseCalendar()
          Construct a Chinese calendar with the default time zone and locale.
ChineseCalendar(TimeZone zone, Locale locale)
          Construct a Chinese calendar with the given time zone and locale.
ChineseCalendar(TimeZone zone, ULocale locale)
          Construct a Chinese calendar with the given time zone and locale.
 
Method Summary
 void add(int field, int amount)
          Override Calendar to handle leap months properly.
protected  int[][][] getFieldResolutionTable()
          Override Calendar to add IS_LEAP_MONTH to the field resolution table.
 String getType()
          Return the current Calendar type.
protected  void handleComputeFields(int julianDay)
          Override Calendar to compute several fields specific to the Chinese calendar system.
protected  int handleComputeMonthStart(int eyear, int month, boolean useMonth)
          Return the Julian day number of day before the first day of the given month in the given extended year.
protected  int[] handleCreateFields()
          Override Calendar to allocate our additional field.
protected  DateFormat handleGetDateFormat(String pattern, ULocale locale)
          Framework method to create a calendar-specific DateFormat object using the the given pattern.
protected  int handleGetExtendedYear()
          Implement abstract Calendar method to return the extended year defined by the current fields.
protected  int handleGetLimit(int field, int limitType)
          Override Calendar to return the limit value for the given field.
protected  int handleGetMonthLength(int extendedYear, int month)
          Override Calendar method to return the number of days in the given extended year and month.
 void roll(int field, int amount)
          Override Calendar to handle leap months properly.
 
Methods inherited from class com.ibm.icu.util.Calendar
after, before, clear, clear, clone, compareTo, compareTo, complete, computeFields, computeGregorianFields, computeGregorianMonthStart, computeJulianDay, computeMillisInDay, computeTime, computeZoneOffset, equals, fieldDifference, fieldName, floorDivide, floorDivide, floorDivide, floorDivide, get, getActualMaximum, getActualMinimum, getAvailableLocales, getAvailableULocales, getDateTimeFormat, getDateTimeFormat, getDayOfWeekType, getDisplayName, getDisplayName, getFieldCount, getFirstDayOfWeek, getGreatestMinimum, getGregorianDayOfMonth, getGregorianDayOfYear, getGregorianMonth, getGregorianYear, getInstance, getInstance, getInstance, getInstance, getInstance, getInstance, getLeastMaximum, getLimit, getLocale, getMaximum, getMinimalDaysInFirstWeek, getMinimum, getStamp, getTime, getTimeInMillis, getTimeZone, getWeekendTransition, gregorianMonthLength, gregorianPreviousMonthLength, handleComputeJulianDay, handleGetDateFormat, handleGetYearLength, hashCode, internalGet, internalGet, internalGetTimeInMillis, internalSet, isEquivalentTo, isGregorianLeapYear, isLenient, isSet, isWeekend, isWeekend, julianDayToDayOfWeek, julianDayToMillis, millisToJulianDay, newerField, newestStamp, pinField, prepareGetActual, resolveFields, roll, set, set, set, set, setFirstDayOfWeek, setLenient, setMinimalDaysInFirstWeek, setTime, setTimeInMillis, setTimeZone, toString, validateField, validateField, validateFields, weekNumber, weekNumber
 
Methods inherited from class java.lang.Object
finalize, getClass, notify, notifyAll, wait, wait, wait
 

Field Detail

IS_LEAP_MONTH

public static int IS_LEAP_MONTH
Field indicating whether or not the current month is a leap month. Should have a value of 0 for non-leap months, and 1 for leap months.

Constructor Detail

ChineseCalendar

public ChineseCalendar()
Construct a Chinese calendar with the default time zone and locale.


ChineseCalendar

public ChineseCalendar(TimeZone zone,
                       Locale locale)
Construct a Chinese calendar with the given time zone and locale.

Parameters:
zone - time zone for this calendar
locale - locale for this calendar

ChineseCalendar

public ChineseCalendar(TimeZone zone,
                       ULocale locale)
Construct a Chinese calendar with the given time zone and locale.

Parameters:
zone - time zone for this calendar
locale - ulocale for this calendar
Method Detail

handleCreateFields

protected int[] handleCreateFields()
Override Calendar to allocate our additional field.

Overrides:
handleCreateFields in class Calendar

handleGetLimit

protected int handleGetLimit(int field,
                             int limitType)
Override Calendar to return the limit value for the given field.

Specified by:
handleGetLimit in class Calendar
Parameters:
field - one of the above field numbers
limitType - one of MINIMUM, GREATEST_MINIMUM, LEAST_MAXIMUM, or MAXIMUM

handleGetExtendedYear

protected int handleGetExtendedYear()
Implement abstract Calendar method to return the extended year defined by the current fields. This will use either the ERA and YEAR field as the cycle and year-of-cycle, or the EXTENDED_YEAR field as the continuous year count, depending on which is newer.

Specified by:
handleGetExtendedYear in class Calendar
Returns:
the extended year

handleGetMonthLength

protected int handleGetMonthLength(int extendedYear,
                                   int month)
Override Calendar method to return the number of days in the given extended year and month.

Note: This method also reads the IS_LEAP_MONTH field to determine whether or not the given month is a leap month.

Overrides:
handleGetMonthLength in class Calendar

handleGetDateFormat

protected DateFormat handleGetDateFormat(String pattern,
                                         ULocale locale)
Framework method to create a calendar-specific DateFormat object using the the given pattern. This method is responsible for creating the calendar- specific DateFormat and DateFormatSymbols objects as needed.

Overrides:
handleGetDateFormat in class Calendar
Parameters:
pattern - the pattern, specific to the DateFormat subclass
locale - the locale for which the symbols should be drawn
Returns:
a DateFormat appropriate to this calendar

getFieldResolutionTable

protected int[][][] getFieldResolutionTable()
Override Calendar to add IS_LEAP_MONTH to the field resolution table.

Overrides:
getFieldResolutionTable in class Calendar
See Also:
Calendar.resolveFields(int[][][])

add

public void add(int field,
                int amount)
Override Calendar to handle leap months properly.

Overrides:
add in class Calendar
Parameters:
field - the time field.
amount - the amount to add to the field.
See Also:
Calendar.roll(int, int)

roll

public void roll(int field,
                 int amount)
Override Calendar to handle leap months properly.

Overrides:
roll in class Calendar
Parameters:
field - the calendar field to roll.
amount - the amount by which the field should be rolled.
See Also:
Calendar.roll(int, boolean), Calendar.add(int, int)

handleComputeFields

protected void handleComputeFields(int julianDay)
Override Calendar to compute several fields specific to the Chinese calendar system. These are: The DAY_OF_WEEK and DOW_LOCAL fields are already set when this method is called. The getGregorianXxx() methods return Gregorian calendar equivalents for the given Julian day.

Compute the ChineseCalendar-specific field IS_LEAP_MONTH.

Overrides:
handleComputeFields in class Calendar

handleComputeMonthStart

protected int handleComputeMonthStart(int eyear,
                                      int month,
                                      boolean useMonth)
Return the Julian day number of day before the first day of the given month in the given extended year.

Note: This method reads the IS_LEAP_MONTH field to determine whether the given month is a leap month.

Specified by:
handleComputeMonthStart in class Calendar
Parameters:
eyear - the extended year
month - the zero-based month. The month is also determined by reading the IS_LEAP_MONTH field.
useMonth - if false, compute the day before the first day of the given year, otherwise, compute the day before the first day of the given month
Returns:
the Julian day number of the day before the first day of the given month and year

getType

public String getType()
Return the current Calendar type.

Overrides:
getType in class Calendar
Returns:
type of calendar (gregorian, etc.)


Copyright (c) 2006 IBM Corporation and others.