java.lang.Object | |
↳ | java.util.Calendar |
Known Direct Subclasses |
Calendar
is an abstract base class for converting between a
Date
object and a set of integer fields such as
YEAR
,
MONTH
,
DAY
,
HOUR
, and so on. (A
Date
object represents a
specific instant in time with millisecond precision. See
Date
for
information about the
Date
class.)
Subclasses of
Calendar
interpret a
Date
according to the rules of a specific calendar system.
Like other locale-sensitive classes,
Calendar
provides a class
method,
getInstance
, for getting a default instance of
this class for general use.
Calendar
's
getInstance
method
returns a calendar whose locale is based on system settings and whose time fields
have been initialized with the current date and time:
Calendar rightNow = Calendar.getInstance()
A
Calendar
object can produce all the time field values needed
to implement the date-time formatting for a particular language and calendar
style (for example, Japanese-Gregorian, Japanese-Traditional).
Calendar
defines the range of values returned by certain
fields, as well as their meaning. For example, the first month of the year
has value
MONTH
==
JANUARY
for all calendars.
Other values are defined by the concrete subclass, such as
ERA
and
YEAR
. See individual field documentation and subclass
documentation for details.
When a
Calendar
is
lenient
, it accepts a wider
range of field values than it produces. For example, a lenient
GregorianCalendar
interprets
MONTH
==
JANUARY
,
DAY_OF_MONTH
== 32 as February 1. A
non-lenient
GregorianCalendar
throws an exception when given
out-of-range field settings. When calendars recompute field values for return
by
get()
, they normalize them. For example, a
GregorianCalendar
always produces
DAY_OF_MONTH
values between 1 and the length of the month.
Calendar
defines a locale-specific seven day week using two
parameters: the first day of the week and the minimal days in first week
(from 1 to 7). These numbers are taken from the locale resource data when a
Calendar
is constructed. They may also be specified explicitly
through the API.
When setting or getting the
WEEK_OF_MONTH
or
WEEK_OF_YEAR
fields,
Calendar
must determine
the first week of the month or year as a reference point. The first week of a
month or year is defined as the earliest seven day period beginning on
getFirstDayOfWeek()
and containing at least
getMinimalDaysInFirstWeek()
days of that month or year. Weeks
numbered ..., -1, 0 precede the first week; weeks numbered 2, 3,... follow
it. Note that the normalized numbering returned by
get()
may
be different. For example, a specific
Calendar
subclass may
designate the week before week 1 of a year as week
n
of the
previous year.
When computing a
Date
from time fields, two special
circumstances may arise: there may be insufficient information to compute the
Date
(such as only year and month but no day in the month), or
there may be inconsistent information (such as "Tuesday, July 15, 1996" --
July 15, 1996 is actually a Monday).
Insufficient information. The calendar will use default information to specify the missing fields. This may vary by calendar; for the Gregorian calendar, the default for a field is the same as that of the start of the epoch: i.e., YEAR = 1970, MONTH = JANUARY, DATE = 1, etc.
Inconsistent information. If fields conflict, the calendar will give preference to fields set more recently. For example, when determining the day, the calendar will look for one of the following combinations of fields. The most recent combination, as determined by the most recently set single field, will be used.
For the time of day:MONTH + DAY_OF_MONTH MONTH + WEEK_OF_MONTH + DAY_OF_WEEK MONTH + DAY_OF_WEEK_IN_MONTH + DAY_OF_WEEK DAY_OF_YEAR DAY_OF_WEEK + WEEK_OF_YEAR
HOUR_OF_DAY AM_PM + HOUR
Note: There are certain possible ambiguities in interpretation of certain singular times, which are resolved in the following ways:
The date or time format strings are not part of the definition of a calendar,
as those must be modifiable or overridable by the user at runtime. Use
DateFormat
to format dates.
Field manipulation methods
Calendar
fields can be changed using three methods:
set()
,
add()
, and
roll()
.
set(f, value)
changes field
f
to
value
. In addition, it sets an internal member variable to
indicate that field
f
has been changed. Although field
f
is changed immediately, the calendar's milliseconds is not
recomputed until the next call to
get()
,
getTime()
, or
getTimeInMillis()
is made. Thus,
multiple calls to
set()
do not trigger multiple, unnecessary
computations. As a result of changing a field using
set()
,
other fields may also change, depending on the field, the field value, and
the calendar system. In addition,
get(f)
will not necessarily
return
value
after the fields have been recomputed. The
specifics are determined by the concrete calendar class.
Example
: Consider a
GregorianCalendar
originally
set to August 31, 1999. Calling
set(Calendar.MONTH,
Calendar.SEPTEMBER)
sets the calendar to September 31, 1999. This is a temporary internal
representation that resolves to October 1, 1999 if
getTime()
is
then called. However, a call to
set(Calendar.DAY_OF_MONTH, 30)
before the call to
getTime()
sets the calendar to September
30, 1999, since no recomputation occurs after
set()
itself.
add(f, delta)
adds
delta
to
field
f
. This is equivalent to calling
set(f,
get(f) + delta)
with two adjustments:
Add rule 1 . The value of field
f
after the call minus the value of fieldf
before the call isdelta
, modulo any overflow that has occurred in fieldf
. 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
f
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 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.
In addition, unlike
set()
,
add()
forces an
immediate recomputation of the calendar's milliseconds and all fields.
Example
: Consider a
GregorianCalendar
originally
set to August 31, 1999. Calling
add(Calendar.MONTH, 13)
sets
the calendar to September 30, 2000.
Add rule 1
sets the
MONTH
field to September, since adding 13 months to August
gives September of the next year. Since
DAY_OF_MONTH
cannot be
31 in September in a
GregorianCalendar
,
add rule 2
sets the
DAY_OF_MONTH
to 30, the closest possible value.
Although it is a smaller field,
DAY_OF_WEEK
is not adjusted by
rule 2, since it is expected to change when the month changes in a
GregorianCalendar
.
roll(f, delta)
adds
delta
to
field
f
without changing larger fields. This is equivalent to
calling
add(f, delta)
with the following adjustment:
Roll rule . Larger fields are unchanged after the call. A larger field represents a larger unit of time.
DAY_OF_MONTH
is a larger field thanHOUR
.
Example
: Consider a
GregorianCalendar
originally
set to August 31, 1999. Calling
roll(Calendar.MONTH,
8)
sets
the calendar to April 30,
1999
. Add rule 1 sets the
MONTH
field to April. Using a
GregorianCalendar
,
the
DAY_OF_MONTH
cannot be 31 in the month April. Add rule 2
sets it to the closest possible value, 30. Finally, the
roll rule
maintains the
YEAR
field value of 1999.
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).
Usage model
. To motivate the behavior of
add()
and
roll()
, consider a user interface component with
increment and decrement buttons for the month, day, and year, and an
underlying
GregorianCalendar
. If the interface reads January
31, 1999 and the user presses the month increment button, what should it
read? If the underlying implementation uses
set()
, it might
read March 3, 1999. A better result would be February 28, 1999. Furthermore,
if the user presses the month increment button again, it should read March
31, 1999, not March 28, 1999. By saving the original date and using either
add()
or
roll()
, depending on whether larger
fields should be affected, the user interface can behave as most users will
intuitively expect.
Note:
You should always use
roll
and
add
rather than
attempting to perform arithmetic operations directly on the fields of a
Calendar
. It is quite possible for
Calendar
subclasses
to have fields with non-linear behavior, for example missing months or days
during non-leap years. The subclasses'
add
and
roll
methods will take this into account, while simple arithmetic manipulations
may give invalid results.
Constants | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
int | ALL_STYLES |
Requests both
SHORT
and
LONG
styles in the map returned by
getDisplayNames(int, int, Locale)
.
|
|||||||||
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.
|
|||||||||
int | AUGUST |
Value of the
MONTH
field indicating the eighth month of
the year.
|
|||||||||
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.
|
|||||||||
int | DST_OFFSET |
Field number for
get
and
set
indicating the
daylight savings 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.
|
|||||||||
int | FIELD_COUNT | This is the total number of fields in this calendar. | |||||||||
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.
|
|||||||||
int | JULY |
Value of the
MONTH
field indicating the seventh month of
the year.
|
|||||||||
int | JUNE |
Value of the
MONTH
field indicating the sixth month of the
year.
|
|||||||||
int | LONG |
Requests long names (such as "January") from
getDisplayName(int, int, Locale)
or
getDisplayNames(int, int, Locale)
.
|
|||||||||
int | MARCH |
Value of the
MONTH
field indicating the third month of the
year.
|
|||||||||
int | MAY |
Value of the
MONTH
field indicating the fifth month of the
year.
|
|||||||||
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 | NOVEMBER |
Value of the
MONTH
field indicating the eleventh month of
the year.
|
|||||||||
int | OCTOBER |
Value of the
MONTH
field indicating the tenth month of the
year.
|
|||||||||
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.
|
|||||||||
int | SHORT |
Requests short names (such as "Jan") from
getDisplayName(int, int, Locale)
or
getDisplayNames(int, int, Locale)
.
|
|||||||||
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.
|
Fields | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
|
areFieldsSet |
True iff the values in
fields[]
correspond to
time
.
|
|||||||||
|
fields |
Contains broken-down field values for the current value of
time
if
areFieldsSet
is true, or stale data corresponding to some previous value otherwise.
|
|||||||||
|
isSet |
Whether the corresponding element in
field[]
has been set.
|
|||||||||
|
isTimeSet |
Whether
time
corresponds to the values in
fields[]
.
|
|||||||||
|
time | A time in milliseconds since January 1, 1970. |
Protected Constructors | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
|
Constructs a
Calendar
instance using the default
TimeZone
and
Locale
.
|
||||||||||
|
Constructs a
Calendar
instance using the given
TimeZone
and
Locale
.
|
Public Methods | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
|
Adds the given amount to a
Calendar
field.
|
||||||||||
|
Returns whether the
Date
represented by this
Calendar
instance is after the
Date
represented by the parameter.
|
||||||||||
|
Returns whether the
Date
represented by this
Calendar
instance is before the
Date
represented by the parameter.
|
||||||||||
|
Clears the value in the given time field, marking it unset and assigning
it a value of zero.
|
||||||||||
|
Clears the values of all the time fields, marking them all unset and assigning
them all a value of zero.
|
||||||||||
|
Returns a shallow copy of this
Calendar
with the same properties.
|
||||||||||
|
Compares the time represented by this
Calendar
to that represented by the given
Calendar
.
|
||||||||||
|
Compares the given object to this
Calendar
and returns whether they are
equal.
|
||||||||||
|
Returns the value of the given field after computing the field values by
calling
complete()
first.
|
||||||||||
|
Returns the maximum value of the given field for the current date.
|
||||||||||
|
Returns the minimum value of the given field for the current date.
|
||||||||||
|
Returns an array of locales for which custom
Calendar
instances
are available.
|
||||||||||
|
Returns a human-readable string for the value of
field
using the given style and locale.
|
||||||||||
|
Returns a map of human-readable strings to corresponding values,
for the given field, style, and locale.
|
||||||||||
|
Returns the first day of the week for this
Calendar
.
|
||||||||||
|
Returns the greatest minimum value of the given field.
|
||||||||||
|
Constructs a new instance of the
Calendar
subclass appropriate for the
given
Locale
and default
TimeZone
, set to the current date and time.
|
||||||||||
|
Constructs a new instance of the
Calendar
subclass appropriate for the
given
Locale
and given
TimeZone
, set to the current date and time.
|
||||||||||
|
Constructs a new instance of the
Calendar
subclass appropriate for the
default
Locale
and given
TimeZone
, set to the current date and time.
|
||||||||||
|
Constructs a new instance of the
Calendar
subclass appropriate for the
default
Locale
and default
TimeZone
, set to the current date and time.
|
||||||||||
|
Returns the smallest maximum value of the given field.
|
||||||||||
|
Returns the greatest maximum value of the given field.
|
||||||||||
|
Returns the minimal days in the first week of the year.
|
||||||||||
|
Returns the smallest minimum value of the given field.
|
||||||||||
|
Returns the time of this
Calendar
as a
Date
object.
|
||||||||||
|
Returns the time represented by this
Calendar
, recomputing the time from its
fields if necessary.
|
||||||||||
|
Returns the time zone used by this
Calendar
.
|
||||||||||
|
Returns an integer hash code for this object.
|
||||||||||
|
Tests whether this
Calendar
accepts field values which are outside the valid
range for the field.
|
||||||||||
|
Tests whether the given field is set.
|
||||||||||
|
Adds the given amount to the given field and wraps the value of
the field when it goes beyond the maximum or minimum value for the
current date.
|
||||||||||
|
Increment or decrement the given field and wrap the value of the
field when it goes beyond the maximum or minimum value for the current
date.
|
||||||||||
|
Sets the given field to the given value.
|
||||||||||
|
Sets the year, month, day of the month, hour of day, minute, and second fields.
|
||||||||||
|
Sets the year, month, and day of the month fields.
|
||||||||||
|
Sets the year, month, day of the month, hour of day, and minute fields.
|
||||||||||
|
Sets the first day of the week for this
Calendar
.
|
||||||||||
|
Sets whether this
Calendar
accepts field values which are outside the valid
range for the field.
|
||||||||||
|
Sets the minimal days in the first week of the year.
|
||||||||||
|
Sets the time of this
Calendar
.
|
||||||||||
|
Sets the time of this
Calendar
to the given Unix time.
|
||||||||||
|
Sets the
TimeZone
used by this Calendar.
|
||||||||||
|
Returns a string representation of this
Calendar
, showing which fields are set.
|
Protected Methods | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
|
Computes the time from the fields if the time has not already been set.
|
||||||||||
|
Computes the
Calendar
fields from
time
.
|
||||||||||
|
Computes
time
from the Calendar fields.
|
||||||||||
|
Returns the value of the given field without recomputing.
|
[Expand]
Inherited Methods
|
|||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
From class
java.lang.Object
|
|||||||||||
From interface
java.lang.Comparable
|
Requests both
SHORT
and
LONG
styles in the map returned by
getDisplayNames(int, int, Locale)
.
Value of the
AM_PM
field indicating the period of the day
from midnight to just before noon.
Value of the
MONTH
field indicating the fourth month of
the year.
Value of the
MONTH
field indicating the eighth month of
the year.
Field number for
get
and
set
indicating the
day of the month. This is a synonym for
DAY_OF_MONTH
. The
first day of the month has value 1.
Field number for
get
and
set
indicating the
day of the month. This is a synonym for
DATE
. The first
day of the month has value 1.
Field number for
get
and
set
indicating the
ordinal number of the day of the week within the current month. Together
with the
DAY_OF_WEEK
field, this uniquely specifies a day
within a month. Unlike
WEEK_OF_MONTH
and
WEEK_OF_YEAR
, this field's value does
not
depend on
getFirstDayOfWeek()
or
getMinimalDaysInFirstWeek()
.
DAY_OF_MONTH 1
through
7
always correspond to
DAY_OF_WEEK_IN_MONTH
1
;
8
through
15
correspond to
DAY_OF_WEEK_IN_MONTH 2
, and so on.
DAY_OF_WEEK_IN_MONTH 0
indicates the week before
DAY_OF_WEEK_IN_MONTH 1
. Negative values count back from
the end of the month, so the last Sunday of a month is specified as
DAY_OF_WEEK = SUNDAY, DAY_OF_WEEK_IN_MONTH = -1
. Because
negative values count backward they will usually be aligned differently
within the month than positive values. For example, if a month has 31
days,
DAY_OF_WEEK_IN_MONTH -1
will overlap
DAY_OF_WEEK_IN_MONTH 5
and the end of
4
.
Field number for
get
and
set
indicating the
day number within the current year. The first day of the year has value
1.
Value of the
MONTH
field indicating the twelfth month of
the year.
Field number for
get
and
set
indicating the
daylight savings offset in milliseconds.
Value of the
MONTH
field indicating the second month of
the year.
This is the total number of fields in this calendar.
Value of the
DAY_OF_WEEK
field indicating Friday.
Field number for
get
and
set
indicating the
hour of the morning or afternoon.
HOUR
is used for the
12-hour clock. E.g., at 10:04:15.250 PM the
HOUR
is 10.
Field number for
get
and
set
indicating the
hour of the day.
HOUR_OF_DAY
is used for the 24-hour
clock. E.g., at 10:04:15.250 PM the
HOUR_OF_DAY
is 22.
Value of the
MONTH
field indicating the first month of the
year.
Value of the
MONTH
field indicating the seventh month of
the year.
Value of the
MONTH
field indicating the sixth month of the
year.
Requests long names (such as "January") from
getDisplayName(int, int, Locale)
or
getDisplayNames(int, int, Locale)
.
Value of the
MONTH
field indicating the third month of the
year.
Value of the
MONTH
field indicating the fifth month of the
year.
Field number for
get
and
set
indicating the
millisecond within the second. E.g., at 10:04:15.250 PM the
MILLISECOND
is 250.
Field number for
get
and
set
indicating the
minute within the hour. E.g., at 10:04:15.250 PM the
MINUTE
is 4.
Value of the
DAY_OF_WEEK
field indicating Monday.
Field number for
get
and
set
indicating the
month. This is a calendar-specific value. The first month of the year is
JANUARY
; the last depends on the number of months in a
year.
Value of the
MONTH
field indicating the eleventh month of
the year.
Value of the
MONTH
field indicating the tenth month of the
year.
Value of the
AM_PM
field indicating the period of the day
from noon to just before midnight.
Value of the
DAY_OF_WEEK
field indicating Saturday.
Field number for
get
and
set
indicating the
second within the minute. E.g., at 10:04:15.250 PM the
SECOND
is 15.
Value of the
MONTH
field indicating the ninth month of the
year.
Requests short names (such as "Jan") from
getDisplayName(int, int, Locale)
or
getDisplayNames(int, int, Locale)
.
Value of the
DAY_OF_WEEK
field indicating Sunday.
Value of the
DAY_OF_WEEK
field indicating Thursday.
Value of the
DAY_OF_WEEK
field indicating Tuesday.
Value of the
MONTH
field indicating the thirteenth month
of the year. Although
GregorianCalendar
does not use this
value, lunar calendars do.
Value of the
DAY_OF_WEEK
field indicating Wednesday.
Field number for
get
and
set
indicating the
week number within the current month. The first week of the month, as
defined by
getFirstDayOfWeek()
and
getMinimalDaysInFirstWeek()
, has value 1. Subclasses
define the value of
WEEK_OF_MONTH
for days before the
first week of the month.
Field number for
get
and
set
indicating the
week number within the current year. The first week of the year, as
defined by
getFirstDayOfWeek()
and
getMinimalDaysInFirstWeek()
, has value 1. Subclasses
define the value of
WEEK_OF_YEAR
for days before the first
week of the year.
Field number for
get
and
set
indicating the
year. This is a calendar-specific value; see subclass documentation.
Field number for
get
and
set
indicating the
raw offset from GMT in milliseconds.
True iff the values in
fields[]
correspond to
time
. Despite the name, this
is effectively "are the values in fields[] up-to-date?" ---
fields[]
may contain
non-zero values and
isSet[]
may contain
true
values even when
areFieldsSet
is false.
Accessing the fields via
get
will ensure the fields are up-to-date.
Contains broken-down field values for the current value of
time
if
areFieldsSet
is true, or stale data corresponding to some previous value otherwise.
Accessing the fields via
get
will ensure the fields are up-to-date.
The array length is always
FIELD_COUNT
.
Whether the corresponding element in
field[]
has been set. Initially, these are all
false. The first time the fields are computed, these are set to true and remain set even if
the data becomes stale: you
must
check
areFieldsSet
if you want to know
whether the value is up-to-date.
Note that
isSet
is
not
a safe alternative to accessing this array directly,
and will likewise return stale data!
The array length is always
FIELD_COUNT
.
Whether
time
corresponds to the values in
fields[]
. If false,
time
is out-of-date with respect to changes
fields[]
.
Accessing the time via
getTimeInMillis
will always return the correct value.
A time in milliseconds since January 1, 1970. See
isTimeSet
.
Accessing the time via
getTimeInMillis
will always return the correct value.
Constructs a
Calendar
instance using the default
TimeZone
and
Locale
.
Constructs a
Calendar
instance using the given
TimeZone
and
Locale
.
Adds the given amount to a
Calendar
field.
field |
the
Calendar
field to modify.
|
---|---|
value | the amount to add to the field. |
IllegalArgumentException |
if
field
is
DST_OFFSET
or
ZONE_OFFSET
.
|
---|
Returns whether the
Date
represented by this
Calendar
instance is after the
Date
represented by the parameter. The comparison is not dependent on the time
zones of the
Calendar
.
calendar |
the
Calendar
instance to compare.
|
---|
true
when this Calendar is after calendar,
false
otherwise.
IllegalArgumentException | if the time is not set and the time cannot be computed from the current field values. |
---|
Returns whether the
Date
represented by this
Calendar
instance is before the
Date
represented by the parameter. The comparison is not dependent on the
time zones of the
Calendar
.
calendar |
the
Calendar
instance to compare.
|
---|
true
when this Calendar is before calendar,
false
otherwise.
IllegalArgumentException | if the time is not set and the time cannot be computed from the current field values. |
---|
Clears the value in the given time field, marking it unset and assigning it a value of zero. The actual field value will be determined the next time the field is accessed.
Clears the values of all the time fields, marking them all unset and assigning them all a value of zero. The actual field values will be determined the next time the fields are accessed.
Returns a shallow copy of this
Calendar
with the same properties.
Compares the time represented by this
Calendar
to that represented by the given
Calendar
.
Calendar
s are equal, -1 if the time of
this
Calendar
is before the other one, 1 if the time of this
Calendar
is after the other one.
NullPointerException | if the argument is null. |
---|---|
IllegalArgumentException | if the argument does not include a valid time value. |
Compares the given object to this
Calendar
and returns whether they are
equal. The object must be an instance of
Calendar
and have the same
properties.
object | the object to compare this instance with. |
---|
true
if the given object is equal to this
Calendar
,
false
otherwise.
Returns the value of the given field after computing the field values by
calling
complete()
first.
IllegalArgumentException | if the fields are not set, the time is not set, and the time cannot be computed from the current field values. |
---|---|
ArrayIndexOutOfBoundsException |
if the field is not inside the range of possible fields.
The range is starting at 0 up to
FIELD_COUNT
.
|
Returns the maximum value of the given field for the current date. For example, the maximum number of days in the current month.
Returns the minimum value of the given field for the current date.
Returns an array of locales for which custom
Calendar
instances
are available.
Note that Android does not support user-supplied locale service providers.
Returns a human-readable string for the value of
field
using the given style and locale. If no string is available, returns null.
The value is retrieved by invoking
get(field)
.
For example,
getDisplayName(MONTH, SHORT, Locale.US)
will return "Jan"
while
getDisplayName(MONTH, LONG, Locale.US)
will return "January".
field | the field |
---|---|
style |
SHORT
or
LONG
|
locale | the locale |
NullPointerException |
if
locale == null
|
---|---|
IllegalArgumentException |
if
field
or
style
is invalid
|
Returns a map of human-readable strings to corresponding values, for the given field, style, and locale. Returns null if no strings are available.
For example,
getDisplayNames(MONTH, ALL_STYLES, Locale.US)
would
contain mappings from "Jan" and "January" to
JANUARY
, and so on.
field | the field |
---|---|
style |
SHORT
,
LONG
, or
ALL_STYLES
|
locale | the locale |
NullPointerException |
if
locale == null
|
---|---|
IllegalArgumentException |
if
field
or
style
is invalid
|
Returns the first day of the week for this
Calendar
.
Returns the greatest minimum value of the given field. This is the
biggest value that
getActualMinimum
can return for any possible
time.
Constructs a new instance of the
Calendar
subclass appropriate for the
given
Locale
and default
TimeZone
, set to the current date and time.
Constructs a new instance of the
Calendar
subclass appropriate for the
given
Locale
and given
TimeZone
, set to the current date and time.
Constructs a new instance of the
Calendar
subclass appropriate for the
default
Locale
and given
TimeZone
, set to the current date and time.
Constructs a new instance of the
Calendar
subclass appropriate for the
default
Locale
and default
TimeZone
, set to the current date and time.
Returns the smallest maximum value of the given field. This is the
smallest value that
getActualMaximum()
can return for any
possible time.
Returns the greatest maximum value of the given field. This returns the
biggest value that
get
can return for the given field.
Returns the minimal days in the first week of the year.
Returns the smallest minimum value of the given field. this returns the
smallest value that
get
can return for the given field.
Returns the time of this
Calendar
as a
Date
object.
IllegalArgumentException | if the time is not set and the time cannot be computed from the current field values. |
---|
Returns the time represented by this
Calendar
, recomputing the time from its
fields if necessary.
IllegalArgumentException | if the time is not set and the time cannot be computed from the current field values. |
---|
Returns an integer hash code for this object. By contract, any two
objects for which
equals(Object)
returns
true
must return
the same hash code value. This means that subclasses of
Object
usually override both methods or neither method.
Note that hash values must not change over time unless information used in equals comparisons also changes.
See
Writing a correct
hashCode
method
if you intend implementing your own
hashCode
method.
Tests whether this
Calendar
accepts field values which are outside the valid
range for the field.
Tests whether the given field is set. Note that the interpretation of "is set" is
somewhat technical. In particular, it does
not
mean that the field's value is up
to date. If you want to know whether a field contains an up-to-date value, you must also
check
areFieldsSet
, making this method somewhat useless unless you're a subclass,
in which case you can access the
isSet
array directly.
A field remains "set" from the first time its value is computed until it's cleared by one
of the
clear
methods. Thus "set" does not mean "valid". You probably want to call
get
-- which will update fields as necessary -- rather than try to make use of
this method.
Adds the given amount to the given field and wraps the value of the field when it goes beyond the maximum or minimum value for the current date. Other fields will be adjusted as required to maintain a consistent date.
Increment or decrement the given field and wrap the value of the field when it goes beyond the maximum or minimum value for the current date. Other fields will be adjusted as required to maintain a consistent date.
Sets the given field to the given value.
Sets the year, month, day of the month, hour of day, minute, and second fields.
Other fields are not changed; call
clear()
first if this is not desired.
The month value is 0-based, so it may be clearer to use a constant like
JANUARY
.
Sets the year, month, and day of the month fields.
Other fields are not changed; call
clear()
first if this is not desired.
The month value is 0-based, so it may be clearer to use a constant like
JANUARY
.
Sets the year, month, day of the month, hour of day, and minute fields.
Other fields are not changed; call
clear()
first if this is not desired.
The month value is 0-based, so it may be clearer to use a constant like
JANUARY
.
Sets the first day of the week for this
Calendar
.
The value should be a day of the week such as
MONDAY
.
Sets whether this
Calendar
accepts field values which are outside the valid
range for the field.
Sets the minimal days in the first week of the year.
Sets the time of this
Calendar
to the given Unix time. See
Date
for more
about what this means.
Sets the
TimeZone
used by this Calendar.
Returns a string representation of this
Calendar
, showing which fields are set.
Computes the time from the fields if the time has not already been set. Computes the fields from the time if the fields are not already set.
IllegalArgumentException | if the time is not set and the time cannot be computed from the current field values. |
---|
Computes the
Calendar
fields from
time
.
Computes
time
from the Calendar fields.
IllegalArgumentException | if the time cannot be computed from the current field values. |
---|
Returns the value of the given field without recomputing.