public class GregorianCalendar extends Calendar
GregorianCalendar is a concrete subclass of
Calendar
and provides the standard calendar used by most of the world.
The standard (Gregorian) calendar has 2 eras, BC and AD.
This implementation handles a single discontinuity, which corresponds by
default to the date the Gregorian calendar was instituted (October 15, 1582
in some countries, later in others). The cutover date may be changed by the
caller by calling setGregorianChange().
Historically, in those countries which adopted the Gregorian calendar first,
October 4, 1582 was thus followed by October 15, 1582. This calendar models
this correctly. Before the Gregorian cutover, GregorianCalendar
implements the Julian calendar. The only difference between the Gregorian
and the Julian calendar is the leap year rule. The Julian calendar specifies
leap years every four years, whereas the Gregorian calendar omits century
years which are not divisible by 400.
GregorianCalendar implements proleptic Gregorian and
Julian calendars. That is, dates are computed by extrapolating the current
rules indefinitely far backward and forward in time. As a result,
GregorianCalendar may be used for all years to generate
meaningful and consistent results. However, dates obtained using
GregorianCalendar are historically accurate only from March 1, 4
AD onward, when modern Julian calendar rules were adopted. Before this date,
leap year rules were applied irregularly, and before 45 BC the Julian
calendar did not even exist.
Prior to the institution of the Gregorian calendar, New Year's Day was March 25. To avoid confusion, this calendar always uses January 1. A manual adjustment may be made if desired for dates that are prior to the Gregorian changeover and which fall between January 1 and March 24.
Values calculated for the WEEK_OF_YEAR field range from 1 to
53. Week 1 for a year is the earliest seven day period starting on
getFirstDayOfWeek() that contains at least
getMinimalDaysInFirstWeek() days from that year. It thus
depends on the values of getMinimalDaysInFirstWeek(),
getFirstDayOfWeek(), and the day of the week of January 1.
Weeks between week 1 of one year and week 1 of the following year are
numbered sequentially from 2 to 52 or 53 (as needed).
For example, January 1, 1998 was a Thursday. If
getFirstDayOfWeek() is MONDAY and
getMinimalDaysInFirstWeek() is 4 (these are the values
reflecting ISO 8601 and many national standards), then week 1 of 1998 starts
on December 29, 1997, and ends on January 4, 1998. If, however,
getFirstDayOfWeek() is SUNDAY, then week 1 of 1998
starts on January 4, 1998, and ends on January 10, 1998; the first three days
of 1998 then are part of week 53 of 1997.
Values calculated for the WEEK_OF_MONTH field range from 0 or
1 to 4 or 5. Week 1 of a month (the days with WEEK_OF_MONTH =
1) is the earliest set of at least
getMinimalDaysInFirstWeek() contiguous days in that month,
ending on the day before getFirstDayOfWeek(). Unlike
week 1 of a year, week 1 of a month may be shorter than 7 days, need
not start on getFirstDayOfWeek(), and will not include days of
the previous month. Days of a month before week 1 have a
WEEK_OF_MONTH of 0.
For example, if getFirstDayOfWeek() is SUNDAY
and getMinimalDaysInFirstWeek() is 4, then the first week of
January 1998 is Sunday, January 4 through Saturday, January 10. These days
have a WEEK_OF_MONTH of 1. Thursday, January 1 through
Saturday, January 3 have a WEEK_OF_MONTH of 0. If
getMinimalDaysInFirstWeek() is changed to 3, then January 1
through January 3 have a WEEK_OF_MONTH of 1.
Example:
// get the supported ids for GMT-08:00 (Pacific Standard Time)
String[] ids = TimeZone.getAvailableIDs(-8 * 60 * 60 * 1000);
// if no ids were returned, something is wrong. get out.
if (ids.length == 0)
System.exit(0);
// begin output
System.out.println("Current Time");
// create a Pacific Standard Time time zone
SimpleTimeZone pdt = new SimpleTimeZone(-8 * 60 * 60 * 1000, ids[0]);
// set up rules for daylight savings time
pdt.setStartRule(Calendar.MARCH, 2, Calendar.SUNDAY, 2 * 60 * 60 * 1000);
pdt.setEndRule(Calendar.NOVEMBER, 1, Calendar.SUNDAY, 2 * 60 * 60 * 1000);
// create a GregorianCalendar with the Pacific Daylight time zone
// and the current date and time
Calendar calendar = new GregorianCalendar(pdt);
Date trialTime = new Date();
calendar.setTime(trialTime);
// print out a bunch of interesting things
System.out.println("ERA: " + calendar.get(Calendar.ERA));
System.out.println("YEAR: " + calendar.get(Calendar.YEAR));
System.out.println("MONTH: " + calendar.get(Calendar.MONTH));
System.out.println("WEEK_OF_YEAR: " + calendar.get(Calendar.WEEK_OF_YEAR));
System.out.println("WEEK_OF_MONTH: " + calendar.get(Calendar.WEEK_OF_MONTH));
System.out.println("DATE: " + calendar.get(Calendar.DATE));
System.out.println("DAY_OF_MONTH: " + calendar.get(Calendar.DAY_OF_MONTH));
System.out.println("DAY_OF_YEAR: " + calendar.get(Calendar.DAY_OF_YEAR));
System.out.println("DAY_OF_WEEK: " + calendar.get(Calendar.DAY_OF_WEEK));
System.out.println("DAY_OF_WEEK_IN_MONTH: "
+ calendar.get(Calendar.DAY_OF_WEEK_IN_MONTH));
System.out.println("AM_PM: " + calendar.get(Calendar.AM_PM));
System.out.println("HOUR: " + calendar.get(Calendar.HOUR));
System.out.println("HOUR_OF_DAY: " + calendar.get(Calendar.HOUR_OF_DAY));
System.out.println("MINUTE: " + calendar.get(Calendar.MINUTE));
System.out.println("SECOND: " + calendar.get(Calendar.SECOND));
System.out.println("MILLISECOND: " + calendar.get(Calendar.MILLISECOND));
System.out.println("ZONE_OFFSET: "
+ (calendar.get(Calendar.ZONE_OFFSET)/(60*60*1000)));
System.out.println("DST_OFFSET: "
+ (calendar.get(Calendar.DST_OFFSET)/(60*60*1000)));
System.out.println("Current Time, with hour reset to 3");
calendar.clear(Calendar.HOUR_OF_DAY); // so doesn't override
calendar.set(Calendar.HOUR, 3);
System.out.println("ERA: " + calendar.get(Calendar.ERA));
System.out.println("YEAR: " + calendar.get(Calendar.YEAR));
System.out.println("MONTH: " + calendar.get(Calendar.MONTH));
System.out.println("WEEK_OF_YEAR: " + calendar.get(Calendar.WEEK_OF_YEAR));
System.out.println("WEEK_OF_MONTH: " + calendar.get(Calendar.WEEK_OF_MONTH));
System.out.println("DATE: " + calendar.get(Calendar.DATE));
System.out.println("DAY_OF_MONTH: " + calendar.get(Calendar.DAY_OF_MONTH));
System.out.println("DAY_OF_YEAR: " + calendar.get(Calendar.DAY_OF_YEAR));
System.out.println("DAY_OF_WEEK: " + calendar.get(Calendar.DAY_OF_WEEK));
System.out.println("DAY_OF_WEEK_IN_MONTH: "
+ calendar.get(Calendar.DAY_OF_WEEK_IN_MONTH));
System.out.println("AM_PM: " + calendar.get(Calendar.AM_PM));
System.out.println("HOUR: " + calendar.get(Calendar.HOUR));
System.out.println("HOUR_OF_DAY: " + calendar.get(Calendar.HOUR_OF_DAY));
System.out.println("MINUTE: " + calendar.get(Calendar.MINUTE));
System.out.println("SECOND: " + calendar.get(Calendar.SECOND));
System.out.println("MILLISECOND: " + calendar.get(Calendar.MILLISECOND));
System.out.println("ZONE_OFFSET: "
+ (calendar.get(Calendar.ZONE_OFFSET)/(60*60*1000))); // in hours
System.out.println("DST_OFFSET: "
+ (calendar.get(Calendar.DST_OFFSET)/(60*60*1000))); // in hours
GregorianCalendar usually should be instantiated using
Calendar.getInstance(ULocale) passing in a ULocale
with the tag "@calendar=gregorian".
Calendar,
TimeZone,
Serialized FormCalendar.FormatConfiguration, Calendar.WeekData| Modifier and Type | Field and Description |
|---|---|
static int |
AD
Value of the
ERA field indicating
the common era (Anno Domini), also known as CE. |
static int |
BC
Value of the
ERA field indicating
the period before the common era (before Christ), also known as BCE. |
protected boolean |
invertGregorian
Used by handleComputeJulianDay() and handleComputeMonthStart().
|
protected boolean |
isGregorian
Used by handleComputeJulianDay() and handleComputeMonthStart().
|
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, IS_LEAP_MONTH, 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, WALLTIME_FIRST, WALLTIME_LAST, WALLTIME_NEXT_VALID, WEDNESDAY, WEEK_OF_MONTH, WEEK_OF_YEAR, WEEKDAY, WEEKEND, WEEKEND_CEASE, WEEKEND_ONSET, YEAR, YEAR_WOY, ZONE_OFFSET| Constructor and Description |
|---|
GregorianCalendar()
Constructs a default GregorianCalendar using the current time
in the default time zone with the default
FORMAT locale. |
GregorianCalendar(int year,
int month,
int date)
Constructs a GregorianCalendar with the given date set
in the default time zone with the default
FORMAT locale. |
GregorianCalendar(int year,
int month,
int date,
int hour,
int minute)
Constructs a GregorianCalendar with the given date
and time set for the default time zone with the default
FORMAT locale. |
GregorianCalendar(int year,
int month,
int date,
int hour,
int minute,
int second)
Constructs a GregorianCalendar with the given date
and time set for the default time zone with the default
FORMAT locale. |
GregorianCalendar(Locale aLocale)
Constructs a GregorianCalendar based on the current time
in the default time zone with the given locale.
|
GregorianCalendar(TimeZone zone)
Constructs a GregorianCalendar based on the current time
in the given time zone with the default
FORMAT locale. |
GregorianCalendar(TimeZone zone,
Locale aLocale)
Constructs a GregorianCalendar based on the current time
in the given time zone with the given locale.
|
GregorianCalendar(TimeZone zone,
ULocale locale)
Constructs a GregorianCalendar based on the current time
in the given time zone with the given locale.
|
GregorianCalendar(ULocale locale)
Constructs a GregorianCalendar based on the current time
in the default time zone with the given locale.
|
| Modifier and Type | Method and Description |
|---|---|
int |
getActualMaximum(int field)
Return the maximum value that this field could have, given the current date.
|
int |
getActualMinimum(int field)
Return the minimum value that this field could have, given the current date.
|
Date |
getGregorianChange()
Gets the Gregorian Calendar change date.
|
String |
getType()
Returns the calendar type name string for this Calendar object.
|
protected void |
handleComputeFields(int julianDay)
Override Calendar to compute several fields specific to the hybrid
Gregorian-Julian calendar system.
|
protected int |
handleComputeJulianDay(int bestField)
Subclasses may override this.
|
protected int |
handleComputeMonthStart(int eyear,
int month,
boolean useMonth)
Return JD of start of given month/year
|
protected int |
handleGetExtendedYear()
Returns the extended year defined by the current fields.
|
protected int |
handleGetLimit(int field,
int limitType)
Subclass API for defining limits of different types.
|
protected int |
handleGetMonthLength(int extendedYear,
int month)
Returns the number of days in the given month of the given extended
year of this calendar system.
|
protected int |
handleGetYearLength(int eyear)
Returns the number of days in the given extended year of this
calendar system.
|
int |
hashCode()
Override hashCode.
|
boolean |
isEquivalentTo(Calendar other)
Returns true if the given Calendar object is equivalent to this
one.
|
boolean |
isLeapYear(int year)
Determines if the given year is a leap year.
|
void |
roll(int field,
int amount)
Roll a field by a signed amount.
|
void |
setGregorianChange(Date date)
Sets the GregorianCalendar change date.
|
add, after, before, clear, clear, clone, compareTo, complete, computeFields, computeGregorianFields, computeGregorianMonthStart, computeJulianDay, computeMillisInDay, computeTime, computeZoneOffset, equals, fieldDifference, fieldName, floorDivide, floorDivide, floorDivide, floorDivide, get, getAvailableLocales, getAvailableULocales, getDateTimeFormat, getDateTimeFormat, getDateTimePattern, getDayOfWeekType, getDefaultDayInMonth, getDefaultMonthInYear, getDisplayName, getDisplayName, getFieldCount, getFieldResolutionTable, getFirstDayOfWeek, getGreatestMinimum, getGregorianDayOfMonth, getGregorianDayOfYear, getGregorianMonth, getGregorianYear, getInstance, getInstance, getInstance, getInstance, getInstance, getInstance, getKeywordValuesForLocale, getLeastMaximum, getLimit, getLocale, getMaximum, getMinimalDaysInFirstWeek, getMinimum, getRelatedYear, getRepeatedWallTimeOption, getSkippedWallTimeOption, getStamp, getTime, getTimeInMillis, getTimeZone, getWeekData, getWeekDataForRegion, getWeekendTransition, gregorianMonthLength, gregorianPreviousMonthLength, handleCreateFields, handleGetDateFormat, handleGetDateFormat, handleGetDateFormat, handleGetDateFormat, haveDefaultCentury, internalGet, internalGet, internalGetTimeInMillis, internalSet, isGregorianLeapYear, isLenient, isSet, isWeekend, isWeekend, julianDayToDayOfWeek, julianDayToMillis, millisToJulianDay, newerField, newestStamp, pinField, prepareGetActual, resolveFields, roll, set, set, set, set, setFirstDayOfWeek, setLenient, setMinimalDaysInFirstWeek, setRelatedYear, setRepeatedWallTimeOption, setSkippedWallTimeOption, setTime, setTimeInMillis, setTimeZone, setWeekData, toString, validateField, validateField, validateFields, weekNumber, weekNumberpublic static final int BC
ERA field indicating
the period before the common era (before Christ), also known as BCE.
The sequence of years at the transition from BC to AD is
..., 2 BC, 1 BC, 1 AD, 2 AD,...Calendar.ERA,
Constant Field Valuespublic static final int AD
ERA field indicating
the common era (Anno Domini), also known as CE.
The sequence of years at the transition from BC to AD is
..., 2 BC, 1 BC, 1 AD, 2 AD,...Calendar.ERA,
Constant Field Valuesprotected transient boolean isGregorian
protected transient boolean invertGregorian
public GregorianCalendar()
FORMAT locale.ULocale.Category.FORMATpublic GregorianCalendar(TimeZone zone)
FORMAT locale.zone - the given time zone.ULocale.Category.FORMATpublic GregorianCalendar(Locale aLocale)
aLocale - the given locale.public GregorianCalendar(ULocale locale)
locale - the given ulocale.public GregorianCalendar(TimeZone zone, Locale aLocale)
zone - the given time zone.aLocale - the given locale.public GregorianCalendar(TimeZone zone, ULocale locale)
zone - the given time zone.locale - the given ulocale.public GregorianCalendar(int year,
int month,
int date)
FORMAT locale.year - the value used to set the YEAR time field in the calendar.month - the value used to set the MONTH time field in the calendar.
Month value is 0-based. e.g., 0 for January.date - the value used to set the DATE time field in the calendar.ULocale.Category.FORMATpublic GregorianCalendar(int year,
int month,
int date,
int hour,
int minute)
FORMAT locale.year - the value used to set the YEAR time field in the calendar.month - the value used to set the MONTH time field in the calendar.
Month value is 0-based. e.g., 0 for January.date - the value used to set the DATE time field in the calendar.hour - the value used to set the HOUR_OF_DAY time field
in the calendar.minute - the value used to set the MINUTE time field
in the calendar.ULocale.Category.FORMATpublic GregorianCalendar(int year,
int month,
int date,
int hour,
int minute,
int second)
FORMAT locale.year - the value used to set the YEAR time field in the calendar.month - the value used to set the MONTH time field in the calendar.
Month value is 0-based. e.g., 0 for January.date - the value used to set the DATE time field in the calendar.hour - the value used to set the HOUR_OF_DAY time field
in the calendar.minute - the value used to set the MINUTE time field
in the calendar.second - the value used to set the SECOND time field
in the calendar.ULocale.Category.FORMATprotected int handleGetLimit(int field,
int limitType)
CalendarERA YEAR MONTH WEEK_OF_YEAR WEEK_OF_MONTH DAY_OF_MONTH DAY_OF_YEAR DAY_OF_WEEK_IN_MONTH YEAR_WOY EXTENDED_YEAR
handleGetLimit in class Calendarfield - one of the above field numberslimitType - one of MINIMUM, GREATEST_MINIMUM,
LEAST_MAXIMUM, or MAXIMUMpublic void setGregorianChange(Date date)
To obtain a pure Julian calendar, set the change date to
Date(Long.MAX_VALUE). To obtain a pure Gregorian calendar,
set the change date to Date(Long.MIN_VALUE).
date - the given Gregorian cutover date.public final Date getGregorianChange()
public boolean isLeapYear(int year)
year - the given year.public boolean isEquivalentTo(Calendar other)
isEquivalentTo in class Calendarother - the Calendar to be compared with this Calendarpublic int hashCode()
hashCode in class CalendarObject.equals(java.lang.Object)public void roll(int field,
int amount)
roll in class Calendarfield - the calendar field to roll.amount - the amount by which the field should be rolled.Calendar.roll(int, boolean),
Calendar.add(int, int)public int getActualMinimum(int field)
getActualMinimum in class Calendarfield - the field whose actual minimum value is desired.Calendar.getMinimum(int),
Calendar.getGreatestMinimum(int)public int getActualMaximum(int field)
getActualMaximum in class Calendarfield - the field whose maximum is desiredCalendar.getMaximum(int),
Calendar.getLeastMaximum(int)protected int handleGetMonthLength(int extendedYear,
int month)
CalendarhandleGetMonthLength in class Calendarprotected int handleGetYearLength(int eyear)
CalendarhandleGetYearLength in class Calendarprotected void handleComputeFields(int julianDay)
handleComputeFields in class Calendarprotected int handleGetExtendedYear()
CalendarhandleGetExtendedYear in class Calendarprotected int handleComputeJulianDay(int bestField)
CalendarhandleComputeJulianDay in class Calendarprotected int handleComputeMonthStart(int eyear,
int month,
boolean useMonth)
handleComputeMonthStart in class Calendareyear - the extended yearmonth - the zero-based month, or 0 if useMonth is falseuseMonth - if false, compute the day before the first day of
the given year, otherwise, compute the day before the first day of
the given monthpublic String getType()
See type="old type name" for the calendar attribute of locale IDs at http://www.unicode.org/reports/tr35/#Key_Type_Definitions