java.lang.Object | ||
↳ | java.util.Calendar | |
↳ | java.util.GregorianCalendar |
Known Direct Subclasses |
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.
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
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.
The clear
methods set 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
|
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.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
Constants | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
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. |
[Expand]
Inherited Constants | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
From class
java.util.Calendar
|
[Expand]
Inherited Fields | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
From class
java.util.Calendar
|
Public Constructors | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Constructs a default
GregorianCalendar using the current time
in the default time zone with the default locale. | |||||||||||
Constructs a
GregorianCalendar based on the current time
in the given time zone with the default locale. | |||||||||||
Constructs a
GregorianCalendar based on the current time
in the default time zone with the given locale. | |||||||||||
Constructs a
GregorianCalendar based on the current time
in the given time zone with the given locale. | |||||||||||
Constructs a
GregorianCalendar with the given date set
in the default time zone with the default locale. | |||||||||||
Constructs a
GregorianCalendar with the given date
and time set for the default time zone with the default locale. | |||||||||||
Constructs a GregorianCalendar with the given date
and time set for the default time zone with the default locale.
|
Public Methods | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Adds the specified (signed) amount of time to the given calendar field,
based on the calendar's rules.
| |||||||||||
Creates and returns a copy of this object.
| |||||||||||
Compares this
GregorianCalendar to the specified
Object . | |||||||||||
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. | |||||||||||
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. | |||||||||||
Returns the highest minimum value for the given calendar field
of this
GregorianCalendar instance. | |||||||||||
Gets the Gregorian Calendar change date.
| |||||||||||
Returns the lowest maximum value for the given calendar field
of this
GregorianCalendar instance. | |||||||||||
Returns the maximum value for the given calendar field of this
GregorianCalendar instance. | |||||||||||
Returns the minimum value for the given calendar field of this
GregorianCalendar instance. | |||||||||||
Gets the time zone.
| |||||||||||
Generates the hash code for this
GregorianCalendar object. | |||||||||||
Determines if the given year is a leap year.
| |||||||||||
Adds or subtracts (up/down) a single unit of time on the given time
field without changing larger fields.
| |||||||||||
Adds a signed amount to the specified calendar field without changing larger fields.
| |||||||||||
Sets the
GregorianCalendar change date. | |||||||||||
Sets the time zone with the given time zone value.
|
Protected Methods | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Converts the time value (millisecond offset from the Epoch) to calendar field values.
| |||||||||||
Converts calendar field values to the time value (millisecond
offset from the Epoch).
|
[Expand]
Inherited Methods | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
From class
java.util.Calendar
| |||||||||||
From class
java.lang.Object
| |||||||||||
From interface
java.lang.Comparable
|
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,...
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,...
Constructs a default GregorianCalendar
using the current time
in the default time zone with the default locale.
Constructs a GregorianCalendar
based on the current time
in the given time zone with the default locale.
zone | the given time zone. |
---|
Constructs a GregorianCalendar
based on the current time
in the default time zone with the given locale.
aLocale | the given locale. |
---|
Constructs a GregorianCalendar
based on the current time
in the given time zone with the given locale.
zone | the given time zone. |
---|---|
aLocale | the given locale. |
Constructs a GregorianCalendar
with the given date set
in the default time zone with the default locale.
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.
|
Constructs a GregorianCalendar
with the given date
and time set for the default time zone with the default locale.
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.
|
Constructs a GregorianCalendar with the given date and time set for the default time zone with the default locale.
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.
|
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.
field | the calendar field. |
---|---|
amount | the amount of date or time to be added to the field. |
IllegalArgumentException | if field is
ZONE_OFFSET , DST_OFFSET , or unknown,
or if any calendar fields have out-of-range values in
non-lenient mode.
|
---|
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.
obj | the object to compare with. |
---|
true
if this object is equal to obj
;
false
otherwise.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.
field | the calendar field |
---|
GregorianCalendar
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.
field | the calendar field |
---|
GregorianCalendar
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.
field | the calendar field. |
---|
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.
GregorianCalendar
object.
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.
field | the calendar 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.
field | the calendar 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.
field | the calendar field. |
---|
Gets the time zone.
Generates the hash code for this GregorianCalendar
object.
Determines if the given year is a leap year. Returns true
if
the given year is a leap year. To specify BC year numbers,
1 - year number
must be given. For example, year BC 4 is
specified as -3.
year | the given year. |
---|
true
if the given year is a leap year; false
otherwise.
Adds or subtracts (up/down) a single unit of time on the given time field without changing larger fields.
Example: Consider a GregorianCalendar
originally set to December 31, 1999. Calling roll(Calendar.MONTH, true)
sets the calendar to January 31, 1999. The YEAR
field is unchanged
because it is a larger field than MONTH
.
field | the time field. |
---|---|
up | indicates if the value of the specified calendar field is to be
rolled up or rolled down. Use true if rolling up, false otherwise. |
IllegalArgumentException | if field is
ZONE_OFFSET , DST_OFFSET , or unknown,
or if any calendar fields have out-of-range values in
non-lenient mode. |
---|
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 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 an
IllegalArgumentException
is thrown.
Example: Consider a GregorianCalendar
originally set to August 31, 1999. Calling roll(Calendar.MONTH,
8)
sets the calendar to April 30, 1999. Using a
GregorianCalendar
, the DAY_OF_MONTH
field cannot
be 31 in the month April. DAY_OF_MONTH
is set to the closest possible
value, 30. The YEAR
field maintains the value of 1999 because it
is a larger field than MONTH
.
Example: Consider a GregorianCalendar
originally set to Sunday June 6, 1999. Calling
roll(Calendar.WEEK_OF_MONTH, -1)
sets the calendar to
Tuesday June 1, 1999, whereas calling
add(Calendar.WEEK_OF_MONTH, -1)
sets the calendar to
Sunday May 30, 1999. This is because the roll rule imposes an
additional constraint: The MONTH
must not change when the
WEEK_OF_MONTH
is 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, the DAY_OF_WEEK
, an invariant
when changing the WEEK_OF_MONTH
, is set to Tuesday, the
closest possible value to Sunday (where Sunday is the first day of the
week).
field | the calendar field. |
---|---|
amount | the signed amount to add to field . |
IllegalArgumentException | if field is
ZONE_OFFSET , DST_OFFSET , or unknown,
or if any calendar fields have out-of-range values in
non-lenient mode. |
---|
Sets the GregorianCalendar
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.
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. |
---|
Sets the time zone with the given time zone value.
zone | the given time zone. |
---|
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 the
complete
method.
Converts calendar field values to the time value (millisecond offset from the Epoch).
IllegalArgumentException | if any calendar fields are invalid. |
---|