Serializable, Cloneable, Comparable<Calendar>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.
Values calculated for the Calendar#WEEK_OF_YEAR field range from 1 to 53. The first week of a
calendar year is the earliest seven day period starting on Calendar#getFirstDayOfWeek() that contains at
least Calendar#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 Calendar#setFirstDayOfWeek(int) and
Calendar#setMinimalDaysInFirstWeek(int).
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.
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 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
|
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
Calendar.Builder| 限定符和类型 | 字段 | 说明 |
|---|---|---|
static int |
AD |
Value of the
ERA field indicating
the common era (Anno Domini), also known as CE. |
static int |
BC |
Value of the
ERA field indicating
the period before the common era (before Christ), also known as BCE. |
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| 构造器 | 说明 |
|---|---|
GregorianCalendar() |
Constructs a default
GregorianCalendar using the current time
in the default time zone with the default
Locale.Category#FORMAT 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.
|
GregorianCalendar(Locale aLocale) |
Constructs a
GregorianCalendar based on the current time
in the default time zone with the given locale. |
GregorianCalendar(TimeZone zone) |
Constructs a
GregorianCalendar based on the current time
in the given time zone with the default
Locale.Category#FORMAT locale. |
GregorianCalendar(TimeZone zone,
Locale aLocale) |
Constructs a
GregorianCalendar based on the current time
in the given time zone with the given locale. |
| 限定符和类型 | 方法 | 说明 |
|---|---|---|
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.
|
protected void |
computeFields() |
Converts the time value (millisecond offset from the Epoch) to calendar field values.
|
protected void |
computeTime() |
Converts calendar field values to the time value (millisecond
offset from the Epoch).
|
boolean |
equals(Object obj) |
Compares this
GregorianCalendar to the specified
Object. |
static GregorianCalendar |
from(ZonedDateTime zdt) |
Obtains an instance of
GregorianCalendar with the default locale
from a ZonedDateTime 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
Calendar#getFirstDayOfWeek(),
Calendar#getMinimalDaysInFirstWeek(),
getGregorianChange and
Calendar#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
Calendar#getFirstDayOfWeek(),
Calendar#getMinimalDaysInFirstWeek(),
getGregorianChange and
Calendar#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. |
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 |
getWeeksInWeekYear() |
Returns the number of weeks in the week year
represented by this
GregorianCalendar. |
int |
getWeekYear() |
Returns 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.
|
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. |
ZonedDateTime |
toZonedDateTime() |
Converts this object to a
ZonedDateTime that represents
the same point on the time-line as this GregorianCalendar. |
after, before, clear, clear, compareTo, complete, get, getAvailableCalendarTypes, getAvailableLocales, getDisplayName, getDisplayNames, getFirstDayOfWeek, getInstance, getInstance, getInstance, getInstance, getMinimalDaysInFirstWeek, getTime, getTimeInMillis, internalGet, isLenient, isSet, set, set, set, set, setFirstDayOfWeek, setLenient, setMinimalDaysInFirstWeek, setTime, setTimeInMillis, toInstant, toStringpublic static final int AD
ERA field indicating
the common era (Anno Domini), also known as CE.
The sequence of years at the transition from BC to AD is
..., 2 BC, 1 BC, 1 AD, 2 AD,...Calendar.ERA,
常量字段值public static final int BC
ERA field indicating
the period before the common era (before Christ), also known as BCE.
The sequence of years at the transition from BC to AD is
..., 2 BC, 1 BC, 1 AD, 2 AD,...Calendar.ERA,
常量字段值public GregorianCalendar()
GregorianCalendar using the current time
in the default time zone with the default
Locale.Category#FORMAT locale.public GregorianCalendar(TimeZone zone)
GregorianCalendar based on the current time
in the given time zone with the default
Locale.Category#FORMAT locale.zone - the given time zone.public GregorianCalendar(Locale aLocale)
GregorianCalendar based on the current time
in the default time zone with the given locale.aLocale - the given locale.public GregorianCalendar(TimeZone zone, Locale aLocale)
GregorianCalendar based on the current time
in the given time zone with the given locale.zone - the given time zone.aLocale - the given locale.public GregorianCalendar(int year,
int month,
int dayOfMonth)
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.public GregorianCalendar(int year,
int month,
int dayOfMonth,
int hourOfDay,
int minute)
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.public GregorianCalendar(int year,
int month,
int dayOfMonth,
int hourOfDay,
int minute,
int second)
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 void setGregorianChange(Date date)
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.public final Date getGregorianChange()
GregorianCalendar object.public boolean isLeapYear(int year)
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.public String getCalendarType()
"gregory" as the calendar type.getCalendarType 在类中 Calendar"gregory"Locale.Builder.setLocale(Locale),
Locale.Builder.setUnicodeLocaleKeyword(String, String)public boolean equals(Object obj)
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.equals 在类中 Calendarobj - the object to compare with.true if this object is equal to obj;
false otherwise.Calendar.compareTo(Calendar)public int hashCode()
GregorianCalendar object.hashCode 在类中 CalendarObject.equals(java.lang.Object),
System.identityHashCode(java.lang.Object)public void add(int field,
int amount)
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.
add 在类中 Calendarfield - 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.Calendar.roll(int,int),
Calendar.set(int,int)public void roll(int field,
boolean up)
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.
roll 在类中 Calendarup - indicates if the value of the specified calendar field is to be
rolled up or rolled down. Use true if rolling up, false otherwise.field - the time 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.add(int,int),
Calendar.set(int,int)public void roll(int field,
int amount)
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 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).
roll 在类中 Calendarfield - 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.roll(int,boolean),
add(int,int),
Calendar.set(int,int)public int getMinimum(int field)
GregorianCalendar instance. The minimum value is
defined as the smallest value returned by the Calendar#get(int) method for any possible time value,
taking into consideration the current values of the
Calendar#getFirstDayOfWeek(),
Calendar#getMinimalDaysInFirstWeek(),
getGregorianChange and
Calendar#getTimeZone() methods.getMinimum 在类中 Calendarfield - the calendar field.getMaximum(int),
getGreatestMinimum(int),
getLeastMaximum(int),
getActualMinimum(int),
getActualMaximum(int)public int getMaximum(int field)
GregorianCalendar instance. The maximum value is
defined as the largest value returned by the Calendar#get(int) method for any possible time value,
taking into consideration the current values of the
Calendar#getFirstDayOfWeek(),
Calendar#getMinimalDaysInFirstWeek(),
getGregorianChange and
Calendar#getTimeZone() methods.getMaximum 在类中 Calendarfield - the calendar field.getMinimum(int),
getGreatestMinimum(int),
getLeastMaximum(int),
getActualMinimum(int),
getActualMaximum(int)public int getGreatestMinimum(int field)
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
Calendar#getFirstDayOfWeek(),
Calendar#getMinimalDaysInFirstWeek(),
getGregorianChange and
Calendar#getTimeZone() methods.getGreatestMinimum 在类中 Calendarfield - the calendar field.getMinimum(int),
getMaximum(int),
getLeastMaximum(int),
getActualMinimum(int),
getActualMaximum(int)public int getLeastMaximum(int field)
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
Calendar#getFirstDayOfWeek(),
Calendar#getMinimalDaysInFirstWeek(),
getGregorianChange and
Calendar#getTimeZone() methods.getLeastMaximum 在类中 Calendarfield - the calendar fieldgetMinimum(int),
getMaximum(int),
getGreatestMinimum(int),
getActualMinimum(int),
getActualMaximum(int)public int getActualMinimum(int field)
Calendar#getFirstDayOfWeek(),
Calendar#getMinimalDaysInFirstWeek(),
getGregorianChange and
Calendar#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.
getActualMinimum 在类中 Calendarfield - the calendar fieldGregorianCalendargetMinimum(int),
getMaximum(int),
getGreatestMinimum(int),
getLeastMaximum(int),
getActualMaximum(int)public int getActualMaximum(int field)
Calendar#getFirstDayOfWeek(),
Calendar#getMinimalDaysInFirstWeek(),
getGregorianChange and
Calendar#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 Calendar#WEEK_OF_YEAR based on the Calendar#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.
getActualMaximum 在类中 Calendarfield - the calendar fieldGregorianCalendargetMinimum(int),
getMaximum(int),
getGreatestMinimum(int),
getLeastMaximum(int),
getActualMinimum(int)public TimeZone getTimeZone()
CalendargetTimeZone 在类中 Calendarpublic void setTimeZone(TimeZone zone)
CalendarsetTimeZone 在类中 Calendarzone - the given time zone.public final boolean isWeekDateSupported()
true indicating this GregorianCalendar
supports week dates.isWeekDateSupported 在类中 Calendartrue (always)getWeekYear(),
setWeekDate(int,int,int),
getWeeksInWeekYear()public int getWeekYear()
GregorianCalendar. 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 the Calendar#YEAR
(calendar year) value.
This method calls Calendar#complete() before
calculating the week year.
getWeekYear 在类中 CalendarGregorianCalendar.
If the Calendar#ERA value is BC, 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.IllegalArgumentException - if any of the calendar fields is invalid in non-lenient mode.isWeekDateSupported(),
getWeeksInWeekYear(),
Calendar.getFirstDayOfWeek(),
Calendar.getMinimalDaysInFirstWeek()public void setWeekDate(int weekYear,
int weekOfYear,
int dayOfWeek)
GregorianCalendar to the date given by the
date specifiers - weekYear,
weekOfYear, and dayOfWeek. weekOfYear
follows the WEEK_OF_YEAR
numbering. The dayOfWeek value must be one of the
Calendar#DAY_OF_WEEK values: Calendar#SUNDAY to Calendar#SATURDAY.
Note that the numeric day-of-week representation differs from
the ISO 8601 standard, and that the weekOfYear
numbering is compatible with the standard when
getFirstDayOfWeek() is MONDAY and
getMinimalDaysInFirstWeek() is 4.
Unlike the set method, all of the calendar fields
and the instant of time value are calculated upon return.
If weekOfYear is out of the valid week-of-year
range in weekYear, the weekYear
and weekOfYear values are adjusted in lenient
mode, or an IllegalArgumentException is thrown in
non-lenient mode.
setWeekDate 在类中 CalendarweekYear - the week yearweekOfYear - the week number based on weekYeardayOfWeek - the day of week value: one of the constants
for the DAY_OF_WEEK field:
Calendar#SUNDAY, ...,
Calendar#SATURDAY.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 modeisWeekDateSupported(),
Calendar.getFirstDayOfWeek(),
Calendar.getMinimalDaysInFirstWeek()public int getWeeksInWeekYear()
GregorianCalendar.
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 while getActualMaximum(WEEK_OF_YEAR) will return
52 for the period: December 31, 2007 to December 28, 2008.
getWeeksInWeekYear 在类中 CalendarCalendar.WEEK_OF_YEAR,
getWeekYear(),
getActualMaximum(int)protected void computeFields()
complete method.computeFields 在类中 CalendarCalendar.complete()protected void computeTime()
computeTime 在类中 CalendarIllegalArgumentException - if any calendar fields are invalid.Calendar.complete(),
Calendar.computeFields()public ZonedDateTime toZonedDateTime()
ZonedDateTime that represents
the same point on the time-line as this GregorianCalendar.
Since this object supports a Julian-Gregorian cutover date and
ZonedDateTime does 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.
public static GregorianCalendar from(ZonedDateTime zdt)
GregorianCalendar with the default locale
from a ZonedDateTime object.
Since ZonedDateTime does 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 has MONDAY as the Calendar#getFirstDayOfWeek() and 4 as the value of the
Calendar#getMinimalDaysInFirstWeek().
ZoneDateTime can store points on the time-line further in the
future and further in the past than GregorianCalendar. In this
scenario, this method will throw an IllegalArgumentException
exception.
zdt - the zoned date-time object to convertNullPointerException - if zdt is nullIllegalArgumentException - if the zoned date-time is too
large to represent as a GregorianCalendar