- java.lang.Object
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- java.util.Calendar
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- java.util.GregorianCalendar
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- All Implemented Interfaces:
Serializable,Cloneable,Comparable<Calendar>
public class GregorianCalendar extends Calendar
GregorianCalendaris a concrete subclass ofCalendarand provides the standard calendar system used by most of the world.GregorianCalendaris 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 callingsetGregorianChange().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,
GregorianCalendarimplements 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.GregorianCalendarimplements 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,GregorianCalendarmay be used for all years to generate meaningful and consistent results. However, dates obtained usingGregorianCalendarare 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_YEARfield range from 1 to 53. The first week of a calendar year is the earliest seven day period starting ongetFirstDayOfWeek()that contains at leastgetMinimalDaysInFirstWeek()days from that year. It thus depends on the values ofgetMinimalDaysInFirstWeek(),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()andgetMinimalDaysInFirstWeek()values are initialized using locale-dependent resources when constructing aGregorianCalendar. The week determination is compatible with the ISO 8601 standard whengetFirstDayOfWeek()isMONDAYandgetMinimalDaysInFirstWeek()is 4, which values are used in locales where the standard is preferred. These values can explicitly be set by callingsetFirstDayOfWeek()andsetMinimalDaysInFirstWeek().A week year is in sync with a
WEEK_OF_YEARcycle. 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()isMONDAYandgetMinimalDaysInFirstWeek()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()isSUNDAY, 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_MONTHfield range from 0 to 6. Week 1 of a month (the days withWEEK_OF_MONTH = 1) is the earliest set of at leastgetMinimalDaysInFirstWeek()contiguous days in that month, ending on the day beforegetFirstDayOfWeek(). Unlike week 1 of a year, week 1 of a month may be shorter than 7 days, need not start ongetFirstDayOfWeek(), and will not include days of the previous month. Days of a month before week 1 have aWEEK_OF_MONTHof 0.For example, if
getFirstDayOfWeek()isSUNDAYandgetMinimalDaysInFirstWeek()is 4, then the first week of January 1998 is Sunday, January 4 through Saturday, January 10. These days have aWEEK_OF_MONTHof 1. Thursday, January 1 through Saturday, January 3 have aWEEK_OF_MONTHof 0. IfgetMinimalDaysInFirstWeek()is changed to 3, then January 1 through January 3 have aWEEK_OF_MONTHof 1.Default Fields Values
The
clearmethod sets calendar field(s) undefined.GregorianCalendaruses the following default value for each calendar field if its value is undefined.Field Default Value ERAADYEAR1970MONTHJANUARYDAY_OF_MONTH1DAY_OF_WEEKthe first day of weekWEEK_OF_MONTH0DAY_OF_WEEK_IN_MONTH1AM_PMAMHOUR, HOUR_OF_DAY, MINUTE, SECOND, MILLISECOND0
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- Since:
- 1.1
- See Also:
TimeZone, Serialized Form
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Nested Class Summary
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Nested classes/interfaces declared in class java.util.Calendar
Calendar.Builder
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Field Summary
Fields Modifier and Type Field Description static intADValue of theERAfield indicating the common era (Anno Domini), also known as CE.static intBCValue of theERAfield indicating the period before the common era (before Christ), also known as BCE.-
Fields declared in class java.util.Calendar
ALL_STYLES, AM, AM_PM, APRIL, areFieldsSet, AUGUST, DATE, DAY_OF_MONTH, DAY_OF_WEEK, DAY_OF_WEEK_IN_MONTH, DAY_OF_YEAR, DECEMBER, DST_OFFSET, ERA, FEBRUARY, FIELD_COUNT, fields, FRIDAY, HOUR, HOUR_OF_DAY, isSet, isTimeSet, JANUARY, JULY, JUNE, LONG, LONG_FORMAT, LONG_STANDALONE, MARCH, MAY, MILLISECOND, MINUTE, MONDAY, MONTH, NARROW_FORMAT, NARROW_STANDALONE, NOVEMBER, OCTOBER, PM, SATURDAY, SECOND, SEPTEMBER, SHORT, SHORT_FORMAT, SHORT_STANDALONE, SUNDAY, THURSDAY, time, TUESDAY, UNDECIMBER, WEDNESDAY, WEEK_OF_MONTH, WEEK_OF_YEAR, YEAR, ZONE_OFFSET
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Constructor Summary
Constructors Constructor Description GregorianCalendar()Constructs a defaultGregorianCalendarusing the current time in the default time zone with the defaultFORMATlocale.GregorianCalendar(int year, int month, int dayOfMonth)Constructs aGregorianCalendarwith 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 aGregorianCalendarwith 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.GregorianCalendar(Locale aLocale)Constructs aGregorianCalendarbased on the current time in the default time zone with the given locale.GregorianCalendar(TimeZone zone)Constructs aGregorianCalendarbased on the current time in the given time zone with the defaultFORMATlocale.GregorianCalendar(TimeZone zone, Locale aLocale)Constructs aGregorianCalendarbased on the current time in the given time zone with the given locale.
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description voidadd(int field, int amount)Adds the specified (signed) amount of time to the given calendar field, based on the calendar's rules.protected voidcomputeFields()Converts the time value (millisecond offset from the Epoch) to calendar field values.protected voidcomputeTime()Converts calendar field values to the time value (millisecond offset from the Epoch).booleanequals(Object obj)Compares thisGregorianCalendarto the specifiedObject.static GregorianCalendarfrom(ZonedDateTime zdt)Obtains an instance ofGregorianCalendarwith the default locale from aZonedDateTimeobject.intgetActualMaximum(int field)Returns the maximum value that this calendar field could have, taking into consideration the given time value and the current values of thegetFirstDayOfWeek,getMinimalDaysInFirstWeek,getGregorianChangeandgetTimeZonemethods.intgetActualMinimum(int field)Returns the minimum value that this calendar field could have, taking into consideration the given time value and the current values of thegetFirstDayOfWeek,getMinimalDaysInFirstWeek,getGregorianChangeandgetTimeZonemethods.StringgetCalendarType()Returns"gregory"as the calendar type.intgetGreatestMinimum(int field)Returns the highest minimum value for the given calendar field of thisGregorianCalendarinstance.DategetGregorianChange()Gets the Gregorian Calendar change date.intgetLeastMaximum(int field)Returns the lowest maximum value for the given calendar field of thisGregorianCalendarinstance.intgetMaximum(int field)Returns the maximum value for the given calendar field of thisGregorianCalendarinstance.intgetMinimum(int field)Returns the minimum value for the given calendar field of thisGregorianCalendarinstance.intgetWeeksInWeekYear()Returns the number of weeks in the week year represented by thisGregorianCalendar.intgetWeekYear()Returns the week year represented by thisGregorianCalendar.inthashCode()Generates the hash code for thisGregorianCalendarobject.booleanisLeapYear(int year)Determines if the given year is a leap year.booleanisWeekDateSupported()Returnstrueindicating thisGregorianCalendarsupports week dates.voidroll(int field, boolean up)Adds or subtracts (up/down) a single unit of time on the given time field without changing larger fields.voidroll(int field, int amount)Adds a signed amount to the specified calendar field without changing larger fields.voidsetGregorianChange(Date date)Sets theGregorianCalendarchange date.voidsetWeekDate(int weekYear, int weekOfYear, int dayOfWeek)Sets thisGregorianCalendarto the date given by the date specifiers -weekYear,weekOfYear, anddayOfWeek.ZonedDateTimetoZonedDateTime()Converts this object to aZonedDateTimethat represents the same point on the time-line as thisGregorianCalendar.-
Methods declared in class java.util.Calendar
after, before, clear, clear, clone, compareTo, complete, get, getAvailableCalendarTypes, getAvailableLocales, getDisplayName, getDisplayNames, getFirstDayOfWeek, getInstance, getInstance, getInstance, getInstance, getMinimalDaysInFirstWeek, getTime, getTimeInMillis, getTimeZone, internalGet, isLenient, isSet, set, set, set, set, setFirstDayOfWeek, setLenient, setMinimalDaysInFirstWeek, setTime, setTimeInMillis, setTimeZone, toInstant, toString
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Field Detail
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BC
public static final int BC
Value of theERAfield indicating the period before the common era (before Christ), also known as BCE. The sequence of years at the transition fromBCtoADis ..., 2 BC, 1 BC, 1 AD, 2 AD,...- See Also:
Calendar.ERA, Constant Field Values
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AD
public static final int AD
Value of theERAfield indicating the common era (Anno Domini), also known as CE. The sequence of years at the transition fromBCtoADis ..., 2 BC, 1 BC, 1 AD, 2 AD,...- See Also:
Calendar.ERA, Constant Field Values
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Constructor Detail
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GregorianCalendar
public GregorianCalendar()
Constructs a defaultGregorianCalendarusing the current time in the default time zone with the defaultFORMATlocale.
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GregorianCalendar
public GregorianCalendar(TimeZone zone)
Constructs aGregorianCalendarbased on the current time in the given time zone with the defaultFORMATlocale.- Parameters:
zone- the given time zone.
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GregorianCalendar
public GregorianCalendar(Locale aLocale)
Constructs aGregorianCalendarbased on the current time in the default time zone with the given locale.- Parameters:
aLocale- the given locale.
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GregorianCalendar
public GregorianCalendar(TimeZone zone, Locale aLocale)
Constructs aGregorianCalendarbased on the current time in the given time zone with the given locale.- Parameters:
zone- the given time zone.aLocale- the given locale.
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GregorianCalendar
public GregorianCalendar(int year, int month, int dayOfMonth)Constructs aGregorianCalendarwith the given date set in the default time zone with the default locale.- Parameters:
year- the value used to set theYEARcalendar field in the calendar.month- the value used to set theMONTHcalendar field in the calendar. Month value is 0-based. e.g., 0 for January.dayOfMonth- the value used to set theDAY_OF_MONTHcalendar field in the calendar.
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GregorianCalendar
public GregorianCalendar(int year, int month, int dayOfMonth, int hourOfDay, int minute)Constructs aGregorianCalendarwith the given date and time set for the default time zone with the default locale.- Parameters:
year- the value used to set theYEARcalendar field in the calendar.month- the value used to set theMONTHcalendar field in the calendar. Month value is 0-based. e.g., 0 for January.dayOfMonth- the value used to set theDAY_OF_MONTHcalendar field in the calendar.hourOfDay- the value used to set theHOUR_OF_DAYcalendar field in the calendar.minute- the value used to set theMINUTEcalendar field in the calendar.
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GregorianCalendar
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 theYEARcalendar field in the calendar.month- the value used to set theMONTHcalendar field in the calendar. Month value is 0-based. e.g., 0 for January.dayOfMonth- the value used to set theDAY_OF_MONTHcalendar field in the calendar.hourOfDay- the value used to set theHOUR_OF_DAYcalendar field in the calendar.minute- the value used to set theMINUTEcalendar field in the calendar.second- the value used to set theSECONDcalendar field in the calendar.
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Method Detail
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setGregorianChange
public void setGregorianChange(Date date)
Sets theGregorianCalendarchange 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.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 toDate(Long.MIN_VALUE).- Parameters:
date- the given Gregorian cutover date.
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getGregorianChange
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
GregorianCalendarobject.
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isLeapYear
public boolean isLeapYear(int year)
Determines if the given year is a leap year. Returnstrueif the given year is a leap year. To specify BC year numbers,1 - year numbermust be given. For example, year BC 4 is specified as -3.- Parameters:
year- the given year.- Returns:
trueif the given year is a leap year;falseotherwise.
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getCalendarType
public String getCalendarType()
Returns"gregory"as the calendar type.- Overrides:
getCalendarTypein classCalendar- Returns:
"gregory"- Since:
- 1.8
- See Also:
- Locale extensions,
Locale.Builder.setLocale(Locale),Locale.Builder.setUnicodeLocaleKeyword(String, String)
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equals
public boolean equals(Object obj)
Compares thisGregorianCalendarto the specifiedObject. The result istrueif and only if the argument is aGregorianCalendarobject that represents the same time value (millisecond offset from the Epoch) under the sameCalendarparameters and Gregorian change date as this object.- Overrides:
equalsin classCalendar- Parameters:
obj- the object to compare with.- Returns:
trueif this object is equal toobj;falseotherwise.- See Also:
Calendar.compareTo(Calendar)
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hashCode
public int hashCode()
Generates the hash code for thisGregorianCalendarobject.- Overrides:
hashCodein classCalendar- Returns:
- a hash code value for this object.
- See Also:
Object.equals(java.lang.Object)
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add
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
fieldafter the call minus the value offieldbefore the call isamount, modulo any overflow that has occurred infield. 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
fieldis 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.HOURis a smaller field thanDAY_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.- Specified by:
addin classCalendar- Parameters:
field- the calendar field.amount- the amount of date or time to be added to the field.- Throws:
IllegalArgumentException- iffieldisZONE_OFFSET,DST_OFFSET, or unknown, or if any calendar fields have out-of-range values in non-lenient mode.- See Also:
Calendar.roll(int,int),Calendar.set(int,int)
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roll
public 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.Example: Consider a
GregorianCalendaroriginally set to December 31, 1999. Callingroll(Calendar.MONTH, true)sets the calendar to January 31, 1999. TheYEARfield is unchanged because it is a larger field thanMONTH.- Specified by:
rollin classCalendar- Parameters:
up- indicates if the value of the specified calendar field is to be rolled up or rolled down. Usetrueif rolling up,falseotherwise.field- the time field.- Throws:
IllegalArgumentException- iffieldisZONE_OFFSET,DST_OFFSET, or unknown, or if any calendar fields have out-of-range values in non-lenient mode.- See Also:
add(int,int),Calendar.set(int,int)
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roll
public void roll(int field, int amount)Adds a signed amount to the specified calendar field without changing larger fields. A negative roll amount means to subtract from field without changing larger fields. If the specified amount is 0, this method performs nothing.This method calls
Calendar.complete()before adding the amount so that all the calendar fields are normalized. If there is any calendar field having an out-of-range value in non-lenient mode, then anIllegalArgumentExceptionis thrown.Example: Consider a
GregorianCalendaroriginally set to August 31, 1999. Callingroll(Calendar.MONTH, 8)sets the calendar to April 30, 1999. Using aGregorianCalendar, theDAY_OF_MONTHfield cannot be 31 in the month April.DAY_OF_MONTHis set to the closest possible value, 30. TheYEARfield maintains the value of 1999 because it is a larger field thanMONTH.Example: Consider a
GregorianCalendaroriginally set to Sunday June 6, 1999. Callingroll(Calendar.WEEK_OF_MONTH, -1)sets the calendar to Tuesday June 1, 1999, whereas callingadd(Calendar.WEEK_OF_MONTH, -1)sets the calendar to Sunday May 30, 1999. This is because the roll rule imposes an additional constraint: TheMONTHmust not change when theWEEK_OF_MONTHis rolled. Taken together with add rule 1, the resultant date must be between Tuesday June 1 and Saturday June 5. According to add rule 2, theDAY_OF_WEEK, an invariant when changing theWEEK_OF_MONTH, is set to Tuesday, the closest possible value to Sunday (where Sunday is the first day of the week).- Overrides:
rollin classCalendar- Parameters:
field- the calendar field.amount- the signed amount to add tofield.- Throws:
IllegalArgumentException- iffieldisZONE_OFFSET,DST_OFFSET, or unknown, or if any calendar fields have out-of-range values in non-lenient mode.- Since:
- 1.2
- See Also:
roll(int,boolean),add(int,int),Calendar.set(int,int)
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getMinimum
public int getMinimum(int field)
Returns the minimum value for the given calendar field of thisGregorianCalendarinstance. The minimum value is defined as the smallest value returned by thegetmethod for any possible time value, taking into consideration the current values of thegetFirstDayOfWeek,getMinimalDaysInFirstWeek,getGregorianChangeandgetTimeZonemethods.- Specified by:
getMinimumin classCalendar- 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)
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getMaximum
public int getMaximum(int field)
Returns the maximum value for the given calendar field of thisGregorianCalendarinstance. The maximum value is defined as the largest value returned by thegetmethod for any possible time value, taking into consideration the current values of thegetFirstDayOfWeek,getMinimalDaysInFirstWeek,getGregorianChangeandgetTimeZonemethods.- Specified by:
getMaximumin classCalendar- 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)
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getGreatestMinimum
public int getGreatestMinimum(int field)
Returns the highest minimum value for the given calendar field of thisGregorianCalendarinstance. The highest minimum value is defined as the largest value returned bygetActualMinimum(int)for any possible time value, taking into consideration the current values of thegetFirstDayOfWeek,getMinimalDaysInFirstWeek,getGregorianChangeandgetTimeZonemethods.- Specified by:
getGreatestMinimumin classCalendar- 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)
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getLeastMaximum
public int getLeastMaximum(int field)
Returns the lowest maximum value for the given calendar field of thisGregorianCalendarinstance. The lowest maximum value is defined as the smallest value returned bygetActualMaximum(int)for any possible time value, taking into consideration the current values of thegetFirstDayOfWeek,getMinimalDaysInFirstWeek,getGregorianChangeandgetTimeZonemethods.- Specified by:
getLeastMaximumin classCalendar- 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)
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getActualMinimum
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 thegetFirstDayOfWeek,getMinimalDaysInFirstWeek,getGregorianChangeandgetTimeZonemethods.For example, if the Gregorian change date is January 10, 1970 and the date of this
GregorianCalendaris January 20, 1970, the actual minimum value of theDAY_OF_MONTHfield 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.- Overrides:
getActualMinimumin classCalendar- Parameters:
field- the calendar field- Returns:
- the minimum of the given field for the time value of
this
GregorianCalendar - Since:
- 1.2
- See Also:
getMinimum(int),getMaximum(int),getGreatestMinimum(int),getLeastMaximum(int),getActualMaximum(int)
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getActualMaximum
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 thegetFirstDayOfWeek,getMinimalDaysInFirstWeek,getGregorianChangeandgetTimeZonemethods. For example, if the date of this instance is February 1, 2004, the actual maximum value of theDAY_OF_MONTHfield 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_YEARbased on theYEAR(calendar year) value, not the week year. CallgetWeeksInWeekYear()to get the maximum value ofWEEK_OF_YEARin the week year of thisGregorianCalendar.- Overrides:
getActualMaximumin classCalendar- Parameters:
field- the calendar field- Returns:
- the maximum of the given field for the time value of
this
GregorianCalendar - Since:
- 1.2
- See Also:
getMinimum(int),getMaximum(int),getGreatestMinimum(int),getLeastMaximum(int),getActualMinimum(int)
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isWeekDateSupported
public final boolean isWeekDateSupported()
Returnstrueindicating thisGregorianCalendarsupports week dates.- Overrides:
isWeekDateSupportedin classCalendar- Returns:
true(always)- Since:
- 1.7
- See Also:
getWeekYear(),setWeekDate(int,int,int),getWeeksInWeekYear()
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getWeekYear
public int getWeekYear()
Returns the week year represented by thisGregorianCalendar. The dates in the weeks between 1 and the maximum week number of the week year have the same week year value that may be one year before or after theYEAR(calendar year) value.This method calls
Calendar.complete()before calculating the week year.- Overrides:
getWeekYearin classCalendar- Returns:
- the week year represented by this
GregorianCalendar. If theERAvalue isBC, the year is represented by 0 or a negative number: BC 1 is 0, BC 2 is -1, BC 3 is -2, and so on. - Throws:
IllegalArgumentException- if any of the calendar fields is invalid in non-lenient mode.- Since:
- 1.7
- See Also:
isWeekDateSupported(),getWeeksInWeekYear(),Calendar.getFirstDayOfWeek(),Calendar.getMinimalDaysInFirstWeek()
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setWeekDate
public void setWeekDate(int weekYear, int weekOfYear, int dayOfWeek)Sets thisGregorianCalendarto the date given by the date specifiers -weekYear,weekOfYear, anddayOfWeek.weekOfYearfollows theWEEK_OF_YEARnumbering. ThedayOfWeekvalue must be one of theDAY_OF_WEEKvalues:SUNDAYtoSATURDAY.Note that the numeric day-of-week representation differs from the ISO 8601 standard, and that the
weekOfYearnumbering is compatible with the standard whengetFirstDayOfWeek()isMONDAYandgetMinimalDaysInFirstWeek()is 4.Unlike the
setmethod, all of the calendar fields and the instant of time value are calculated upon return.If
weekOfYearis out of the valid week-of-year range inweekYear, theweekYearandweekOfYearvalues are adjusted in lenient mode, or anIllegalArgumentExceptionis thrown in non-lenient mode.- Overrides:
setWeekDatein classCalendar- Parameters:
weekYear- the week yearweekOfYear- the week number based onweekYeardayOfWeek- the day of week value: one of the constants for theDAY_OF_WEEKfield:SUNDAY, ...,SATURDAY.- Throws:
IllegalArgumentException- if any of the given date specifiers is invalid, or if any of the calendar fields are inconsistent with the given date specifiers in non-lenient mode- Since:
- 1.7
- See Also:
isWeekDateSupported(),Calendar.getFirstDayOfWeek(),Calendar.getMinimalDaysInFirstWeek()
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getWeeksInWeekYear
public int getWeeksInWeekYear()
Returns the number of weeks in the week year represented by thisGregorianCalendar.For example, if this
GregorianCalendar's date is December 31, 2008 with the ISO 8601 compatible setting, this method will return 53 for the period: December 29, 2008 to January 3, 2010 whilegetActualMaximum(WEEK_OF_YEAR)will return 52 for the period: December 31, 2007 to December 28, 2008.- Overrides:
getWeeksInWeekYearin classCalendar- Returns:
- the number of weeks in the week year.
- Since:
- 1.7
- See Also:
Calendar.WEEK_OF_YEAR,getWeekYear(),getActualMaximum(int)
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computeFields
protected void computeFields()
Converts the time value (millisecond offset from the Epoch) to calendar field values. The time is not recomputed first; to recompute the time, then the fields, call thecompletemethod.- Specified by:
computeFieldsin classCalendar- See Also:
Calendar.complete()
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computeTime
protected void computeTime()
Converts calendar field values to the time value (millisecond offset from the Epoch).- Specified by:
computeTimein classCalendar- Throws:
IllegalArgumentException- if any calendar fields are invalid.- See Also:
Calendar.complete(),Calendar.computeFields()
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toZonedDateTime
public ZonedDateTime toZonedDateTime()
Converts this object to aZonedDateTimethat represents the same point on the time-line as thisGregorianCalendar.Since this object supports a Julian-Gregorian cutover date and
ZonedDateTimedoes not, it is possible that the resulting year, month and day will have different values. The result will represent the correct date in the ISO calendar system, which will also be the same value for Modified Julian Days.- Returns:
- a zoned date-time representing the same point on the time-line as this gregorian calendar
- Since:
- 1.8
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from
public static GregorianCalendar from(ZonedDateTime zdt)
Obtains an instance ofGregorianCalendarwith the default locale from aZonedDateTimeobject.Since
ZonedDateTimedoes not support a Julian-Gregorian cutover date and uses ISO calendar system, the return GregorianCalendar is a pure Gregorian calendar and uses ISO 8601 standard for week definitions, which hasMONDAYas theFirstDayOfWeekand4as the value of theMinimalDaysInFirstWeek.ZoneDateTimecan store points on the time-line further in the future and further in the past thanGregorianCalendar. In this scenario, this method will throw anIllegalArgumentExceptionexception.- Parameters:
zdt- the zoned date-time object to convert- Returns:
- the gregorian calendar representing the same point on the time-line as the zoned date-time provided
- Throws:
NullPointerException- ifzdtis nullIllegalArgumentException- if the zoned date-time is too large to represent as aGregorianCalendar- Since:
- 1.8
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