GregorianCalendar

public class GregorianCalendar extends Calendar

GregorianCalendar is a concrete subclass of Calendar and provides the standard calendar system used by most of the world.

GregorianCalendar is a hybrid calendar that supports both the Julian and Gregorian calendar systems with the support of a single discontinuity, which corresponds by default to the Gregorian date when 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 (Julian) was thus followed by October 15, 1582 (Gregorian). 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.

Week Of Year and Week Year

Values calculated for the WEEK_OF_YEAR field range from 1 to 53. The first week of a calendar 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 (exclusive) are numbered sequentially from 2 to 52 or 53 (except for year(s) involved in the Julian-Gregorian transition).

The getFirstDayOfWeek() and getMinimalDaysInFirstWeek() values are initialized using locale-dependent resources when constructing a GregorianCalendar. The week determination is compatible with the ISO 8601 standard when getFirstDayOfWeek() is MONDAY and getMinimalDaysInFirstWeek() is 4, which values are used in locales where the standard is preferred. These values can explicitly be set by calling setFirstDayOfWeek() and setMinimalDaysInFirstWeek().

A week year is in sync with a WEEK_OF_YEAR cycle. All weeks between the first and last weeks (inclusive) have the same week year value. Therefore, the first and last days of a week year may have different calendar year values.

For example, January 1, 1998 is a Thursday. If getFirstDayOfWeek() is MONDAY and getMinimalDaysInFirstWeek() is 4 (ISO 8601 standard compatible setting), then week 1 of 1998 starts on December 29, 1997, and ends on January 4, 1998. The week year is 1998 for the last three days of calendar year 1997. 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 and their week year is 1997.

Week Of Month

Values calculated for the WEEK_OF_MONTH field range from 0 to 6. 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.

Default Fields Values

The clear method sets calendar field(s) undefined. GregorianCalendar uses the following default value for each calendar field if its value is undefined.

Field	Default Value
ERA	AD
YEAR	1970
MONTH	JANUARY
DAY_OF_MONTH	1
DAY_OF_WEEK	the first day of week
WEEK_OF_MONTH	0
DAY_OF_WEEK_IN_MONTH	1
AM_PM	AM
HOUR, HOUR_OF_DAY, MINUTE, SECOND, MILLISECOND	0

Default values are not applicable for the fields not listed above.

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 Saving Time
 pdt.setStartRule(Calendar.APRIL, 1, Calendar.SUNDAY, 2 * 60 * 60 * 1000);
 pdt.setEndRule(Calendar.OCTOBER, -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
 

See Also

• TimeZone

Constant Summary

int	AD	Value of the ERA field indicating the common era (Anno Domini), also known as CE.
int	BC	Value of the ERA field indicating the period before the common era (before Christ), also known as BCE.

Inherited Constant Summary

From class java.util.Calendar

int	ALL_STYLES	A style specifier for getDisplayNames indicating names in all styles, such as "January" and "Jan".
int	AM	Value of the AM_PM field indicating the period of the day from midnight to just before noon.
int	AM_PM	Field number for get and set indicating whether the HOUR is before or after noon.
int	APRIL	Value of the MONTH field indicating the fourth month of the year in the Gregorian and Julian calendars.
int	AUGUST	Value of the MONTH field indicating the eighth month of the year in the Gregorian and Julian calendars.
int	DATE	Field number for get and set indicating the day of the month.
int	DAY_OF_MONTH	Field number for get and set indicating the day of the month.
int	DAY_OF_WEEK	Field number for get and set indicating the day of the week.
int	DAY_OF_WEEK_IN_MONTH	Field number for get and set indicating the ordinal number of the day of the week within the current month.
int	DAY_OF_YEAR	Field number for get and set indicating the day number within the current year.
int	DECEMBER	Value of the MONTH field indicating the twelfth month of the year in the Gregorian and Julian calendars.
int	DST_OFFSET	Field number for get and set indicating the daylight saving offset in milliseconds.
int	ERA	Field number for get and set indicating the era, e.g., AD or BC in the Julian calendar.
int	FEBRUARY	Value of the MONTH field indicating the second month of the year in the Gregorian and Julian calendars.
int	FIELD_COUNT	The number of distinct fields recognized by get and set.
int	FRIDAY	Value of the DAY_OF_WEEK field indicating Friday.
int	HOUR	Field number for get and set indicating the hour of the morning or afternoon.
int	HOUR_OF_DAY	Field number for get and set indicating the hour of the day.
int	JANUARY	Value of the MONTH field indicating the first month of the year in the Gregorian and Julian calendars.
int	JULY	Value of the MONTH field indicating the seventh month of the year in the Gregorian and Julian calendars.
int	JUNE	Value of the MONTH field indicating the sixth month of the year in the Gregorian and Julian calendars.
int	LONG	A style specifier for getDisplayName and getDisplayNames equivalent to LONG_FORMAT.
int	LONG_FORMAT	A style specifier for getDisplayName and getDisplayNames indicating a long name used for format.
int	LONG_STANDALONE	A style specifier for getDisplayName and getDisplayNames indicating a long name used independently, such as a month name as calendar headers.
int	MARCH	Value of the MONTH field indicating the third month of the year in the Gregorian and Julian calendars.
int	MAY	Value of the MONTH field indicating the fifth month of the year in the Gregorian and Julian calendars.
int	MILLISECOND	Field number for get and set indicating the millisecond within the second.
int	MINUTE	Field number for get and set indicating the minute within the hour.
int	MONDAY	Value of the DAY_OF_WEEK field indicating Monday.
int	MONTH	Field number for get and set indicating the month.
int	NARROW_FORMAT	A style specifier for getDisplayName and getDisplayNames indicating a narrow name used for format.
int	NARROW_STANDALONE	A style specifier for getDisplayName and getDisplayNames indicating a narrow name independently.
int	NOVEMBER	Value of the MONTH field indicating the eleventh month of the year in the Gregorian and Julian calendars.
int	OCTOBER	Value of the MONTH field indicating the tenth month of the year in the Gregorian and Julian calendars.
int	PM	Value of the AM_PM field indicating the period of the day from noon to just before midnight.
int	SATURDAY	Value of the DAY_OF_WEEK field indicating Saturday.
int	SECOND	Field number for get and set indicating the second within the minute.
int	SEPTEMBER	Value of the MONTH field indicating the ninth month of the year in the Gregorian and Julian calendars.
int	SHORT	A style specifier for getDisplayName and getDisplayNames equivalent to SHORT_FORMAT.
int	SHORT_FORMAT	A style specifier for getDisplayName and getDisplayNames indicating a short name used for format.
int	SHORT_STANDALONE	A style specifier for getDisplayName and getDisplayNames indicating a short name used independently, such as a month abbreviation as calendar headers.
int	SUNDAY	Value of the DAY_OF_WEEK field indicating Sunday.
int	THURSDAY	Value of the DAY_OF_WEEK field indicating Thursday.
int	TUESDAY	Value of the DAY_OF_WEEK field indicating Tuesday.
int	UNDECIMBER	Value of the MONTH field indicating the thirteenth month of the year.
int	WEDNESDAY	Value of the DAY_OF_WEEK field indicating Wednesday.
int	WEEK_OF_MONTH	Field number for get and set indicating the week number within the current month.
int	WEEK_OF_YEAR	Field number for get and set indicating the week number within the current year.
int	YEAR	Field number for get and set indicating the year.
int	ZONE_OFFSET	Field number for get and set indicating the raw offset from GMT in milliseconds.

Inherited Field Summary

From class java.util.Calendar

protected boolean	areFieldsSet	True if fields[] are in sync with the currently set time.
protected int[]	fields	The calendar field values for the currently set time for this calendar.
protected boolean[]	isSet	The flags which tell if a specified calendar field for the calendar is set.
protected boolean	isTimeSet	True if then the value of time is valid.
protected long	time	The currently set time for this calendar, expressed in milliseconds after January 1, 1970, 0:00:00 GMT.

Public Constructor Summary

	GregorianCalendar() Constructs a default GregorianCalendar using the current time in the default time zone with the default FORMAT locale.
	GregorianCalendar(TimeZone zone) Constructs a GregorianCalendar based on the current time in the given 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, Locale aLocale) Constructs a GregorianCalendar based on the current time in the given time zone with the given locale.
	GregorianCalendar(int year, int month, int dayOfMonth) Constructs a GregorianCalendar with the given date set in the default time zone with the default locale.
	GregorianCalendar(int year, int month, int dayOfMonth, int hourOfDay, int minute) Constructs a GregorianCalendar with the given date and time set for the default time zone with the default locale.
	GregorianCalendar(int year, int month, int dayOfMonth, int hourOfDay, int minute, int second) Constructs a GregorianCalendar with the given date and time set for the default time zone with the default locale.

Public Method Summary

void	add(int field, int amount) Adds the specified (signed) amount of time to the given calendar field, based on the calendar's rules.
Object	clone() Creates and returns a copy of this object.
boolean	equals(Object obj) Compares this GregorianCalendar to the specified Object.
int	getActualMaximum(int field) Returns the maximum value that this calendar field could have, taking into consideration the given time value and the current values of the getFirstDayOfWeek, getMinimalDaysInFirstWeek, getGregorianChange and getTimeZone methods.
int	getActualMinimum(int field) Returns the minimum value that this calendar field could have, taking into consideration the given time value and the current values of the getFirstDayOfWeek, getMinimalDaysInFirstWeek, getGregorianChange and getTimeZone methods.
String	getCalendarType() Returns "gregory" as the calendar type.
int	getGreatestMinimum(int field) Returns the highest minimum value for the given calendar field of this GregorianCalendar instance.
final Date	getGregorianChange() Gets the Gregorian Calendar change date.
int	getLeastMaximum(int field) Returns the lowest maximum value for the given calendar field of this GregorianCalendar instance.
int	getMaximum(int field) Returns the maximum value for the given calendar field of this GregorianCalendar instance.
int	getMinimum(int field) Returns the minimum value for the given calendar field of this GregorianCalendar instance.
TimeZone	getTimeZone() Gets the time zone.
int	getWeekYear() Returns the week year represented by this GregorianCalendar.
int	getWeeksInWeekYear() Returns the number of weeks in the week year represented by this GregorianCalendar.
int	hashCode() Generates the hash code for this GregorianCalendar object.
boolean	isLeapYear(int year) Determines if the given year is a leap year.
final boolean	isWeekDateSupported() Returns true indicating this GregorianCalendar supports week dates.
void	roll(int field, boolean up) Adds or subtracts (up/down) a single unit of time on the given time field without changing larger fields.
void	roll(int field, int amount) Adds a signed amount to the specified calendar field without changing larger fields.
void	setGregorianChange(Date date) Sets the GregorianCalendar change date.
void	setTimeZone(TimeZone zone) Sets the time zone with the given time zone value.
void	setWeekDate(int weekYear, int weekOfYear, int dayOfWeek) Sets this GregorianCalendar to the date given by the date specifiers - weekYear, weekOfYear, and dayOfWeek.

Protected Method Summary

void	computeFields() Converts the time value (millisecond offset from the Epoch) to calendar field values.
void	computeTime() Converts calendar field values to the time value (millisecond offset from the Epoch).

Inherited Method Summary

From class java.util.Calendar

abstract void	add(int field, int amount) Adds or subtracts the specified amount of time to the given calendar field, based on the calendar's rules.
boolean	after(Object when) Returns whether this Calendar represents a time after the time represented by the specified Object.
boolean	before(Object when) Returns whether this Calendar represents a time before the time represented by the specified Object.
final void	clear() Sets all the calendar field values and the time value (millisecond offset from the Epoch) of this Calendar undefined.
final void	clear(int field) Sets the given calendar field value and the time value (millisecond offset from the Epoch) of this Calendar undefined.
Object	clone() Creates and returns a copy of this object.
int	compareTo(Calendar anotherCalendar) Compares the time values (millisecond offsets from the Epoch) represented by two Calendar objects.
void	complete() Fills in any unset fields in the calendar fields.
abstract void	computeFields() Converts the current millisecond time value time to calendar field values in fields[].
abstract void	computeTime() Converts the current calendar field values in fields[] to the millisecond time value time.
boolean	equals(Object obj) Compares this Calendar to the specified Object.
int	get(int field) Returns the value of the given calendar field.
int	getActualMaximum(int field) Returns the maximum value that the specified calendar field could have, given the time value of this Calendar.
int	getActualMinimum(int field) Returns the minimum value that the specified calendar field could have, given the time value of this Calendar.
static Set<String>	getAvailableCalendarTypes() Returns an unmodifiable Set containing all calendar types supported by Calendar in the runtime environment.
synchronized static Locale[]	getAvailableLocales() Returns an array of all locales for which the getInstance methods of this class can return localized instances.
String	getCalendarType() Returns the calendar type of this Calendar.
String	getDisplayName(int field, int style, Locale locale) Returns the string representation of the calendar field value in the given style and locale.
Map<String, Integer>	getDisplayNames(int field, int style, Locale locale) Returns a Map containing all names of the calendar field in the given style and locale and their corresponding field values.
int	getFirstDayOfWeek() Gets what the first day of the week is; e.g., SUNDAY in the U.S., MONDAY in France.
abstract int	getGreatestMinimum(int field) Returns the highest minimum value for the given calendar field of this Calendar instance.
static Calendar	getInstance() Gets a calendar using the default time zone and locale.
static Calendar	getInstance(Locale aLocale) Gets a calendar using the default time zone and specified locale.
static Calendar	getInstance(TimeZone zone, Locale aLocale) Gets a calendar with the specified time zone and locale.
static Calendar	getInstance(TimeZone zone) Gets a calendar using the specified time zone and default locale.
abstract int	getLeastMaximum(int field) Returns the lowest maximum value for the given calendar field of this Calendar instance.
abstract int	getMaximum(int field) Returns the maximum value for the given calendar field of this Calendar instance.
int	getMinimalDaysInFirstWeek() Gets what the minimal days required in the first week of the year are; e.g., if the first week is defined as one that contains the first day of the first month of a year, this method returns 1.
abstract int	getMinimum(int field) Returns the minimum value for the given calendar field of this Calendar instance.
final Date	getTime() Returns a Date object representing this Calendar's time value (millisecond offset from the Epoch").
long	getTimeInMillis() Returns this Calendar's time value in milliseconds.
TimeZone	getTimeZone() Gets the time zone.
int	getWeekYear() Returns the week year represented by this Calendar.
int	getWeeksInWeekYear() Returns the number of weeks in the week year represented by this Calendar.
int	hashCode() Returns a hash code for this calendar.
final int	internalGet(int field) Returns the value of the given calendar field.
boolean	isLenient() Tells whether date/time interpretation is to be lenient.
final boolean	isSet(int field) Determines if the given calendar field has a value set, including cases that the value has been set by internal fields calculations triggered by a get method call.
boolean	isWeekDateSupported() Returns whether this Calendar supports week dates.
abstract void	roll(int field, boolean up) Adds or subtracts (up/down) a single unit of time on the given time field without changing larger fields.
void	roll(int field, int amount) Adds the specified (signed) amount to the specified calendar field without changing larger fields.
final void	set(int year, int month, int date, int hourOfDay, int minute, int second) Sets the values for the fields YEAR, MONTH, DAY_OF_MONTH, HOUR_OF_DAY, MINUTE, and SECOND.
final void	set(int year, int month, int date, int hourOfDay, int minute) Sets the values for the calendar fields YEAR, MONTH, DAY_OF_MONTH, HOUR_OF_DAY, and MINUTE.
void	set(int field, int value) Sets the given calendar field to the given value.
final void	set(int year, int month, int date) Sets the values for the calendar fields YEAR, MONTH, and DAY_OF_MONTH.
void	setFirstDayOfWeek(int value) Sets what the first day of the week is; e.g., SUNDAY in the U.S., MONDAY in France.
void	setLenient(boolean lenient) Specifies whether or not date/time interpretation is to be lenient.
void	setMinimalDaysInFirstWeek(int value) Sets what the minimal days required in the first week of the year are; For example, if the first week is defined as one that contains the first day of the first month of a year, call this method with value 1.
final void	setTime(Date date) Sets this Calendar's time with the given Date.
void	setTimeInMillis(long millis) Sets this Calendar's current time from the given long value.
void	setTimeZone(TimeZone value) Sets the time zone with the given time zone value.
void	setWeekDate(int weekYear, int weekOfYear, int dayOfWeek) Sets the date of this Calendar with the the given date specifiers - week year, week of year, and day of week.
String	toString() Return a string representation of this calendar.

From class java.lang.Object

Object	clone() Creates and returns a copy of this Object.
boolean	equals(Object obj) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Invoked when the garbage collector has detected that this instance is no longer reachable.
final Class<?>	getClass() Returns the unique instance of Class that represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait(long timeout, int nanos) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait(long timeout) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait() Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object.

From interface java.lang.Comparable

abstract int

compareTo(Calendar o) Compares this object with the specified object for order.

Constants

public static final int AD

Value of the 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,...

See Also

• Calendar.ERA

Constant Value: 1

public static final int BC

Value of the 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,...

See Also

• Calendar.ERA

Constant Value: 0

Public Constructors

public GregorianCalendar ()

Constructs a default GregorianCalendar using the current time in the default time zone with the default FORMAT locale.

public GregorianCalendar (TimeZone zone)

Constructs a GregorianCalendar based on the current time in the given time zone with the default FORMAT locale.

Parameters

zone	the given time zone.

public GregorianCalendar (Locale aLocale)

Constructs a GregorianCalendar based on the current time in the default time zone with the given locale.

Parameters

aLocale	the given locale.

public GregorianCalendar (TimeZone zone, Locale aLocale)

Constructs a GregorianCalendar based on the current time in the given time zone with the given locale.

Parameters

zone	the given time zone.
aLocale	the given locale.

public GregorianCalendar (int year, int month, int dayOfMonth)

Constructs a GregorianCalendar with the given date set in the default time zone with the default locale.

Parameters

year	the value used to set the YEAR calendar field in the calendar.
month	the value used to set the MONTH calendar field in the calendar. Month value is 0-based. e.g., 0 for January.
dayOfMonth	the value used to set the DAY_OF_MONTH calendar field in the calendar.

public GregorianCalendar (int year, int month, int dayOfMonth, int hourOfDay, int minute)

Constructs a GregorianCalendar with the given date and time set for the default time zone with the default locale.

Parameters

year	the value used to set the YEAR calendar field in the calendar.
month	the value used to set the MONTH calendar field in the calendar. Month value is 0-based. e.g., 0 for January.
dayOfMonth	the value used to set the DAY_OF_MONTH calendar field in the calendar.
hourOfDay	the value used to set the HOUR_OF_DAY calendar field in the calendar.
minute	the value used to set the MINUTE calendar field in the calendar.

public GregorianCalendar (int year, int month, int dayOfMonth, int hourOfDay, int minute, int second)

Constructs a GregorianCalendar with the given date and time set for the default time zone with the default locale.

Parameters

year	the value used to set the YEAR calendar field in the calendar.
month	the value used to set the MONTH calendar field in the calendar. Month value is 0-based. e.g., 0 for January.
dayOfMonth	the value used to set the DAY_OF_MONTH calendar field in the calendar.
hourOfDay	the value used to set the HOUR_OF_DAY calendar field in the calendar.
minute	the value used to set the MINUTE calendar field in the calendar.
second	the value used to set the SECOND calendar field in the calendar.

Public Methods

public void add (int field, int amount)

Adds the specified (signed) amount of time to the given calendar field, based on the calendar's rules.

Add rule 1. The value of field after the call minus the value of field before the call is amount, modulo any overflow that has occurred in field. Overflow occurs when a field value exceeds its range and, as a result, the next larger field is incremented or decremented and the field value is adjusted back into its range.

Add rule 2. If a smaller field is expected to be invariant, but it is impossible for it to be equal to its prior value because of changes in its minimum or maximum after field is changed, then its value is adjusted to be as close as possible to its expected value. A smaller field represents a smaller unit of time. HOUR is a smaller field than DAY_OF_MONTH. No adjustment is made to smaller fields that are not expected to be invariant. The calendar system determines what fields are expected to be invariant.

Parameters

field	the calendar field.
amount	the amount of date or time to be added to the field.

Throws

IllegalArgumentException	if field is ZONE_OFFSET, DST_OFFSET, or unknown, or if any calendar fields have out-of-range values in non-lenient mode.

public Object clone ()

Creates and returns a copy of this object.

Returns

• a copy of this object.

public boolean equals (Object obj)

Compares this GregorianCalendar to the specified Object. The result is true if and only if the argument is a GregorianCalendar object that represents the same time value (millisecond offset from the Epoch) under the same Calendar parameters and Gregorian change date as this object.

Parameters

obj	the object to compare with.

Returns

• true if this object is equal to obj; false otherwise.

See Also

• Calendar.compareTo(Calendar)

public int getActualMaximum (int field)

Returns the maximum value that this calendar field could have, taking into consideration the given time value and the current values of the getFirstDayOfWeek, getMinimalDaysInFirstWeek, getGregorianChange and getTimeZone methods. For example, if the date of this instance is February 1, 2004, the actual maximum value of the DAY_OF_MONTH field is 29 because 2004 is a leap year, and if the date of this instance is February 1, 2005, it's 28.

This method calculates the maximum value of WEEK_OF_YEAR based on the YEAR (calendar year) value, not the week year. Call getWeeksInWeekYear() to get the maximum value of WEEK_OF_YEAR in the week year of this GregorianCalendar.

Parameters

field	the calendar field

Returns

• the maximum of the given field for the time value of this GregorianCalendar

See Also

• getMinimum(int)
• getMaximum(int)
• getGreatestMinimum(int)
• getLeastMaximum(int)
• getActualMinimum(int)

public int getActualMinimum (int field)

Returns the minimum value that this calendar field could have, taking into consideration the given time value and the current values of the getFirstDayOfWeek, getMinimalDaysInFirstWeek, getGregorianChange and getTimeZone methods.

For example, if the Gregorian change date is January 10, 1970 and the date of this GregorianCalendar is January 20, 1970, the actual minimum value of the DAY_OF_MONTH field is 10 because the previous date of January 10, 1970 is December 27, 1996 (in the Julian calendar). Therefore, December 28, 1969 to January 9, 1970 don't exist.

Parameters

field	the calendar field

Returns

• the minimum of the given field for the time value of this GregorianCalendar

See Also

• getMinimum(int)
• getMaximum(int)
• getGreatestMinimum(int)
• getLeastMaximum(int)
• getActualMaximum(int)

public String getCalendarType ()

Returns "gregory" as the calendar type.

Returns

• "gregory"

public int getGreatestMinimum (int field)

Returns the highest minimum value for the given calendar field of this GregorianCalendar instance. The highest minimum value is defined as the largest value returned by getActualMinimum(int) for any possible time value, taking into consideration the current values of the getFirstDayOfWeek, getMinimalDaysInFirstWeek, getGregorianChange and getTimeZone methods.

Parameters

field	the calendar field.

Returns

• the highest minimum value for the given calendar field.

See Also

• getMinimum(int)
• getMaximum(int)
• getLeastMaximum(int)
• getActualMinimum(int)
• getActualMaximum(int)

public final Date getGregorianChange ()

Gets the Gregorian Calendar change date. This is the point when the switch from Julian dates to Gregorian dates occurred. Default is October 15, 1582 (Gregorian). Previous to this, dates will be in the Julian calendar.

Returns

• the Gregorian cutover date for this GregorianCalendar object.

public int getLeastMaximum (int field)

Returns the lowest maximum value for the given calendar field of this GregorianCalendar instance. The lowest maximum value is defined as the smallest value returned by getActualMaximum(int) for any possible time value, taking into consideration the current values of the getFirstDayOfWeek, getMinimalDaysInFirstWeek, getGregorianChange and getTimeZone methods.

Parameters

field	the calendar field

Returns

• the lowest maximum value for the given calendar field.

See Also

• getMinimum(int)
• getMaximum(int)
• getGreatestMinimum(int)
• getActualMinimum(int)
• getActualMaximum(int)

public int getMaximum (int field)

Returns the maximum value for the given calendar field of this GregorianCalendar instance. The maximum value is defined as the largest value returned by the get method for any possible time value, taking into consideration the current values of the getFirstDayOfWeek, getMinimalDaysInFirstWeek, getGregorianChange and getTimeZone methods.

Parameters

field	the calendar field.

Returns

• the maximum value for the given calendar field.

See Also

• getMinimum(int)
• getGreatestMinimum(int)
• getLeastMaximum(int)
• getActualMinimum(int)
• getActualMaximum(int)

public int getMinimum (int field)

Returns the minimum value for the given calendar field of this GregorianCalendar instance. The minimum value is defined as the smallest value returned by the get method for any possible time value, taking into consideration the current values of the getFirstDayOfWeek, getMinimalDaysInFirstWeek, getGregorianChange and getTimeZone methods.

Parameters

field	the calendar field.

Returns

• the minimum value for the given calendar field.

See Also

• getMaximum(int)
• getGreatestMinimum(int)
• getLeastMaximum(int)
• getActualMinimum(int)
• getActualMaximum(int)

public TimeZone getTimeZone ()

Gets the time zone.

Returns

• the time zone object associated with this calendar.

public int