public abstract class Calendar extends Object implements Serializable, Cloneable, Comparable<Calendar>
Calendar
class is an abstract class that provides methods for converting between
a specific instant in time and a set of calendar fields
such as YEAR
, MONTH
, DAY_OF_MONTH
, HOUR
, and so on, and for
manipulating the calendar fields, such as getting the date of the next week. An instant in time
can be represented by a millisecond value that is an offset from the
Epoch, January 1, 1970 00:00:00.000 GMT (Gregorian).
The class also provides additional fields and methods for implementing a concrete calendar system
outside the package. Those fields and methods are defined as protected
.
Like other locale-sensitive classes, Calendar
provides a class method,
getInstance
, for getting a generally useful object of this type.
Calendar
's getInstance
method returns a Calendar
object
whose calendar fields have been initialized with the current date and time:
Calendar rightNow = Calendar.getInstance();
A Calendar
object can produce all the calendar 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 calendar fields, as well as their meaning. For example, the first month of
the calendar system has value MONTH ==
JANUARY
for all calendars. Other values are defined by the concrete subclass, such as
ERA
. See individual field documentation and subclass documentation for details.
The calendar field values can be set by calling the set
methods. Any field values
set in a Calendar
will not be interpreted until it needs to calculate its time value
(milliseconds from the Epoch) or values of the calendar fields. Calling the get
,
getTimeInMillis
, getTime
, add
and roll
involves such calculation.
Calendar
is always considered in lenient mode. When a Calendar
is in lenient mode, it accepts a wider range of calendar field values than it produces. When a
Calendar
recomputes calendar field values for return by get()
, all of
the calendar fields are normalized. For example, a lenient GregorianCalendar
interprets MONTH == JANUARY
, DAY_OF_MONTH == 32
as February 1.
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 methods for setting their values.
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.
Calendar
will resolve calendar field values to determine the date and
time in the following way.
If there is any conflict in calendar field values, Calendar
gives priorities to
calendar fields that have been set more recently. The following are the default combinations of
the calendar fields. The most recent combination, as determined by the most recently set single
field, will be used.
For the time of day fields:YEAR + MONTH + DAY_OF_MONTH YEAR + MONTH + WEEK_OF_MONTH + DAY_OF_WEEK YEAR + MONTH + DAY_OF_WEEK_IN_MONTH + DAY_OF_WEEK YEAR + DAY_OF_YEAR YEAR + DAY_OF_WEEK + WEEK_OF_YEAR
HOUR_OF_DAY AM_PM + HOUR
If there are any calendar fields whose values haven't been set in the selected field combination,
Calendar
uses their default values. The default value of each field may vary by
concrete calendar systems. For example, in GregorianCalendar
, the default of a field
is the same as that of the start of the Epoch: i.e., YEAR = 1970
, MONTH =
JANUARY
, DAY_OF_MONTH = 1
, etc.
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.
set()
, add()
,
and roll()
.
set(f, value)
changes calendar field f
to
value
. In addition, it sets an internal member variable to indicate that calendar
field f
has been changed. Although calendar field f
is changed
immediately, the calendar's time value in milliseconds is not recomputed until the next call to
get()
, getTime()
, getTimeInMillis()
, add()
,
or roll()
is made. Thus, multiple calls to set()
do not trigger
multiple, unnecessary computations. As a result of changing a calendar field using
set()
, other calendar fields may also change, depending on the calendar field, the
calendar field value, and the calendar system. In addition, get(f)
will not
necessarily return value
set by the call to the set
method after the
calendar 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 date 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 date 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 or other constraints, such as time zone offset changes, 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
.
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.
System.currentTimeMillis()
,
Date
,
TimeZone
,
Serialized FormModifier and Type | Field and Description |
---|---|
static int |
ALL_STYLES
A style specifier indicating names in all styles, such as "January" and "Jan".
|
static int |
AM
Value of the
AM_PM field indicating the period of the day from midnight to just before
noon. |
static int |
AM_PM
Field number for
get and set indicating whether the HOUR
is before or after noon. |
static int |
APRIL
Value of the
MONTH field indicating the fourth month of the year in the Gregorian and
Julian calendars. |
protected boolean |
areFieldsSet
True if
fields[] are in sync with the currently set time. |
static int |
AUGUST
Value of the
MONTH field indicating the eighth month of the year in the Gregorian and
Julian calendars. |
static int |
DATE
Field number for
get and set indicating the day of the month. |
static int |
DAY_OF_MONTH
Field number for
get and set indicating the day of the month. |
static int |
DAY_OF_WEEK
Field number for
get and set indicating the day of the week. |
static 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. |
static int |
DAY_OF_YEAR
Field number for
get and set indicating the day number within the
current year. |
static int |
DECEMBER
Value of the
MONTH field indicating the twelfth month of the year in the Gregorian and
Julian calendars. |
static int |
DST_OFFSET
Field number for
get and set indicating the daylight saving offset in
milliseconds. |
static int |
ERA
Field number for
get and set indicating the era, e.g., AD or BC in the
Julian calendar. |
static int |
FEBRUARY
Value of the
MONTH field indicating the second month of the year in the Gregorian and
Julian calendars. |
static int |
FIELD_COUNT
The number of distinct fields recognized by
get and set . |
protected int[] |
fields
The calendar field values for the currently set time for this calendar.
|
static int |
FRIDAY
Value of the
DAY_OF_WEEK field indicating Friday. |
static int |
HOUR
Field number for
get and set indicating the hour of the morning or
afternoon. |
static int |
HOUR_OF_DAY
Field number for
get and set indicating the hour of the day. |
static int |
JANUARY
Value of the
MONTH field indicating the first month of the year in the Gregorian and
Julian calendars. |
static int |
JULY
Value of the
MONTH field indicating the seventh month of the year in the Gregorian and
Julian calendars. |
static int |
JUNE
Value of the
MONTH field indicating the sixth month of the year in the Gregorian and
Julian calendars. |
static int |
LONG
A style specifier indicating a long name, such as "January".
|
static int |
MARCH
Value of the
MONTH field indicating the third month of the year in the Gregorian and
Julian calendars. |
static int |
MAY
Value of the
MONTH field indicating the fifth month of the year in the Gregorian and
Julian calendars. |
static int |
MILLISECOND
Field number for
get and set indicating the millisecond within the
second. |
static int |
MINUTE
Field number for
get and set indicating the minute within the hour. |
static int |
MONDAY
Value of the
DAY_OF_WEEK field indicating Monday. |
static int |
MONTH
Field number for
get and set indicating the month. |
static int |
NOVEMBER
Value of the
MONTH field indicating the eleventh month of the year in the Gregorian and
Julian calendars. |
static int |
OCTOBER
Value of the
MONTH field indicating the tenth month of the year in the Gregorian and
Julian calendars. |
static int |
PM
Value of the
AM_PM field indicating the period of the day from noon to just before
midnight. |
static int |
SATURDAY
Value of the
DAY_OF_WEEK field indicating Saturday. |
static int |
SECOND
Field number for
get and set indicating the second within the minute. |
static int |
SEPTEMBER
Value of the
MONTH field indicating the ninth month of the year in the Gregorian and
Julian calendars. |
static int |
SHORT
A style specifier indicating a short name, such as "Jan".
|
static int |
SUNDAY
Value of the
DAY_OF_WEEK field indicating Sunday. |
static int |
THURSDAY
Value of the
DAY_OF_WEEK field indicating Thursday. |
protected long |
time
The currently set time for this calendar, expressed in milliseconds after January 1, 1970,
0:00:00 GMT.
|
static int |
TUESDAY
Value of the
DAY_OF_WEEK field indicating Tuesday. |
static int |
UNDECIMBER
Value of the
MONTH field indicating the thirteenth month of the year. |
static int |
WEDNESDAY
Value of the
DAY_OF_WEEK field indicating Wednesday. |
static int |
WEEK_OF_MONTH
Field number for
get and set indicating the week number within the
current month. |
static int |
WEEK_OF_YEAR
Field number for
get and set indicating the week number within the
current year. |
static int |
YEAR
Field number for
get and set indicating the year. |
static int |
ZONE_OFFSET
Field number for
get and set indicating the raw offset from GMT in
milliseconds. |
Modifier | Constructor and Description |
---|---|
protected |
Calendar()
Constructs a Calendar with the default time zone and locale.
|
Modifier and Type | Method and Description |
---|---|
boolean |
after(Object when)
Returns whether this
Calendar represents a time after the time represented by the
specified Object . |
boolean |
before(Object when)
Returns whether this
Calendar represents a time before the time represented by the
specified Object . |
void |
clear()
Sets all the calendar field values and the time value (millisecond offset from the
Epoch) of this
Calendar undefined. |
void |
clear(int field)
Sets the given calendar field value and the time value (millisecond offset from the
Epoch) of this
Calendar undefined. |
Object |
clone()
Creates and returns a copy of this object.
|
int |
compareTo(Calendar anotherCalendar)
Compares the time values (millisecond offsets from the Epoch) represented by
two
Calendar objects. |
protected void |
complete()
Fills in any unset fields in the calendar fields.
|
protected abstract void |
computeFields()
|
protected abstract void |
computeTime()
|
boolean |
equals(Object obj)
Compares this
Calendar to the specified Object . |
int |
get(int field)
Returns the value of the given calendar field.
|
int |
getActualMaximum(int field)
Returns the maximum value that the specified calendar field could have, given the time value of
this
Calendar . |
int |
getActualMinimum(int field)
Returns the minimum value that the specified calendar field could have, given the time value of
this
Calendar . |
int |
getFirstDayOfWeek()
Gets what the first day of the week is; e.g.,
SUNDAY in the U.S.,
MONDAY in France. |
abstract int |
getGreatestMinimum(int field)
Returns the highest minimum value for the given calendar field of this
Calendar
instance. |
static Calendar |
getInstance()
Gets a calendar using the default time zone and locale.
|
static Calendar |
getInstance(TimeZone zone)
Gets a calendar using the specified time zone and default locale.
|
abstract int |
getLeastMaximum(int field)
Returns the lowest maximum value for the given calendar field of this
Calendar
instance. |
abstract int |
getMaximum(int field)
Returns the maximum value for the given calendar field of this
Calendar instance. |
int |
getMinimalDaysInFirstWeek()
Gets what the minimal days required in the first week of the year are; e.g., if the first week is
defined as one that contains the first day of the first month of a year, this method returns 1.
|
abstract int |
getMinimum(int field)
Returns the minimum value for the given calendar field of this
Calendar instance. |
Date |
getTime()
|
long |
getTimeInMillis()
Returns this Calendar's time value in milliseconds.
|
TimeZone |
getTimeZone()
Gets the time zone.
|
int |
hashCode()
Returns a hash code for this calendar.
|
protected int |
internalGet(int field)
Returns the value of the given calendar field.
|
boolean |
isSet(int field)
Determines if the given calendar field has a value set, including cases that
the value has been set by internal fields calculations triggered by a
get method call. |
void |
set(int field,
int value)
Sets the given calendar field to the given value.
|
void |
set(int year,
int month,
int date)
Sets the values for the calendar fields
YEAR , MONTH , and
DAY_OF_MONTH . |
void |
set(int year,
int month,
int date,
int hourOfDay,
int minute)
Sets the values for the calendar fields
YEAR , MONTH ,
DAY_OF_MONTH , HOUR_OF_DAY , and MINUTE . |
void |
set(int year,
int month,
int date,
int hourOfDay,
int minute,
int second)
Sets the values for the fields
YEAR , MONTH , DAY_OF_MONTH ,
HOUR , MINUTE , and SECOND . |
void |
setFirstDayOfWeek(int value)
Sets what the first day of the week is; e.g.,
SUNDAY in the U.S.,
MONDAY in France. |
void |
setMinimalDaysInFirstWeek(int value)
Sets what the minimal days required in the first week of the year are; For example, if the first
week is defined as one that contains the first day of the first month of a year, call this method
with value 1.
|
void |
setTime(Date date)
Sets this Calendar's time with the given
Date . |
void |
setTimeInMillis(long millis)
Sets this Calendar's current time from the given long value.
|
void |
setTimeZone(TimeZone value)
Sets the time zone with the given time zone value.
|
String |
toString()
Return a string representation of this calendar.
|
public static final int ALL_STYLES
SHORT
,
LONG
,
Constant Field Valuespublic static final int AM
AM_PM
field indicating the period of the day from midnight to just before
noon.public static final int AM_PM
get
and set
indicating whether the HOUR
is before or after noon. E.g., at 10:04:15.250 PM the AM_PM
is PM
.AM
,
PM
,
HOUR
,
Constant Field Valuespublic static final int APRIL
MONTH
field indicating the fourth month of the year in the Gregorian and
Julian calendars.protected boolean areFieldsSet
fields[]
are in sync with the currently set time. If false, then the next
attempt to get the value of a field will force a recomputation of all fields from the current
value of time
.public static final int AUGUST
MONTH
field indicating the eighth month of the year in the Gregorian and
Julian calendars.public static final int DATE
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.DAY_OF_MONTH
,
Constant Field Valuespublic static final int DAY_OF_MONTH
get
and set
indicating the day of the month. This is a
synonym for DATE
. The first day of the month has value 1.DATE
,
Constant Field Valuespublic static final int DAY_OF_WEEK
get
and set
indicating the day of the week. This field
takes values SUNDAY
, MONDAY
, TUESDAY
,
WEDNESDAY
, THURSDAY
, FRIDAY
, and SATURDAY
.public static final int DAY_OF_WEEK_IN_MONTH
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 14
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
.DAY_OF_WEEK
,
WEEK_OF_MONTH
,
Constant Field Valuespublic static final int DAY_OF_YEAR
get
and set
indicating the day number within the
current year. The first day of the year has value 1.public static final int DECEMBER
MONTH
field indicating the twelfth month of the year in the Gregorian and
Julian calendars.public static final int DST_OFFSET
get
and set
indicating the daylight saving offset in
milliseconds.
This field reflects the correct daylight saving offset value of the time zone of this
Calendar
if the TimeZone
implementation subclass supports historical
Daylight Saving Time schedule changes.
public static final int ERA
get
and set
indicating the era, e.g., AD or BC in the
Julian calendar. This is a calendar-specific value; see subclass documentation.public static final int FEBRUARY
MONTH
field indicating the second month of the year in the Gregorian and
Julian calendars.public static final int FIELD_COUNT
get
and set
. Field numbers
range from 0..FIELD_COUNT-1
.protected int[] fields
FIELD_COUNT
integers, with index values ERA
through
DST_OFFSET
.public static final int FRIDAY
DAY_OF_WEEK
field indicating Friday.public static final int HOUR
get
and set
indicating the hour of the morning or
afternoon. HOUR
is used for the 12-hour clock (0 - 11). Noon and midnight are
represented by 0, not by 12. E.g., at 10:04:15.250 PM the HOUR
is 10.AM_PM
,
HOUR_OF_DAY
,
Constant Field Valuespublic static final int HOUR_OF_DAY
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.HOUR
,
Constant Field Valuespublic static final int JANUARY
MONTH
field indicating the first month of the year in the Gregorian and
Julian calendars.public static final int JULY
MONTH
field indicating the seventh month of the year in the Gregorian and
Julian calendars.public static final int JUNE
MONTH
field indicating the sixth month of the year in the Gregorian and
Julian calendars.public static final int LONG
SHORT
,
Constant Field Valuespublic static final int MARCH
MONTH
field indicating the third month of the year in the Gregorian and
Julian calendars.public static final int MAY
MONTH
field indicating the fifth month of the year in the Gregorian and
Julian calendars.public static final int MILLISECOND
get
and set
indicating the millisecond within the
second. E.g., at 10:04:15.250 PM the MILLISECOND
is 250.public static final int MINUTE
get
and set
indicating the minute within the hour.
E.g., at 10:04:15.250 PM the MINUTE
is 4.public static final int MONDAY
DAY_OF_WEEK
field indicating Monday.public static final int MONTH
get
and set
indicating the month. This is a
calendar-specific value. The first month of the year in the Gregorian and Julian calendars is
JANUARY
which is 0; the last depends on the number of months in a year.public static final int NOVEMBER
MONTH
field indicating the eleventh month of the year in the Gregorian and
Julian calendars.public static final int OCTOBER
MONTH
field indicating the tenth month of the year in the Gregorian and
Julian calendars.public static final int PM
AM_PM
field indicating the period of the day from noon to just before
midnight.public static final int SATURDAY
DAY_OF_WEEK
field indicating Saturday.public static final int SECOND
get
and set
indicating the second within the minute.
E.g., at 10:04:15.250 PM the SECOND
is 15.public static final int SEPTEMBER
MONTH
field indicating the ninth month of the year in the Gregorian and
Julian calendars.public static final int SHORT
LONG
,
Constant Field Valuespublic static final int SUNDAY
DAY_OF_WEEK
field indicating Sunday.public static final int THURSDAY
DAY_OF_WEEK
field indicating Thursday.protected long time
public static final int TUESDAY
DAY_OF_WEEK
field indicating Tuesday.public static final int UNDECIMBER
MONTH
field indicating the thirteenth month of the year. Although
GregorianCalendar
does not use this value, lunar calendars do.public static final int WEDNESDAY
DAY_OF_WEEK
field indicating Wednesday.public static final int WEEK_OF_MONTH
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.public static final int WEEK_OF_YEAR
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.public static final int YEAR
get
and set
indicating the year. This is a
calendar-specific value; see subclass documentation.public static final int ZONE_OFFSET
get
and set
indicating the raw offset from GMT in
milliseconds.
This field reflects the correct GMT offset value of the time zone of this Calendar
if the TimeZone
implementation subclass supports historical GMT offset changes.
protected Calendar()
TimeZone.getDefault()
public boolean after(Object when)
Calendar
represents a time after the time represented by the
specified Object
. This method is equivalent to:
compareTo(when) > 0if and only if
when
is a Calendar
instance. Otherwise, the method
returns false
.when
- the Object
to be comparedtrue
if the time of this Calendar
is after the time represented
by when
; false
otherwise.compareTo(Calendar)
public boolean before(Object when)
Calendar
represents a time before the time represented by the
specified Object
. This method is equivalent to:
compareTo(when) < 0if and only if
when
is a Calendar
instance. Otherwise, the method
returns false
.when
- the Object
to be comparedtrue
if the time of this Calendar
is before the time
represented by when
; false
otherwise.compareTo(Calendar)
public final void clear()
Calendar
undefined. This means that
isSet()
will return false
for all the calendar fields, and the
date and time calculations will treat the fields as if they had never been set. A
Calendar
implementation class may use its specific default field values for
date/time calculations. For example, GregorianCalendar
uses 1970 if the
YEAR
field value is undefined.clear(int)
public final void clear(int field)
Calendar
undefined. This means that
isSet(field)
will return false
, and the date and time
calculations will treat the field as if it had never been set. A Calendar
implementation class may use the field's specific default value for date and time calculations.
The HOUR_OF_DAY
, HOUR
and AM_PM
fields are handled independently and
the the resolution rule for the time of day is applied. Clearing
one of the fields doesn't reset the hour of day value of this Calendar
. Use
set(Calendar.HOUR_OF_DAY, 0)
to reset the hour value.
field
- the calendar field to be cleared.clear()
public Object clone()
public int compareTo(Calendar anotherCalendar)
Calendar
objects.compareTo
in interface Comparable<Calendar>
anotherCalendar
- the Calendar
to be compared.0
if the time represented by the argument is equal to the time
represented by this Calendar
; a value less than 0
if the time
of this Calendar
is before the time represented by the argument; and a value
greater than 0
if the time of this Calendar
is after the time
represented by the argument.NullPointerException
- if the specified Calendar
is null
.IllegalArgumentException
- if the time value of the specified Calendar
object can't be obtained due
to any invalid calendar values.protected void complete()
computeTime()
method is
called if the time value (millisecond offset from the Epoch) has not been
calculated from calendar field values. Then, the computeFields()
method is called to
calculate all calendar field values.protected abstract void computeFields()
time
to calendar field values in
fields[]
. This allows you to sync up the calendar field values with a new time
that is set for the calendar. The time is not recomputed first; to recompute the time,
then the fields, call the complete()
method.computeTime()
protected abstract void computeTime()
complete()
,
computeFields()
public boolean equals(@Nullable Object obj)
Calendar
to the specified Object
. The result is
true
if and only if the argument is a Calendar
object of the same
calendar system that represents the same time value (millisecond offset from the
Epoch) under the same Calendar
parameters as this object.
The Calendar
parameters are the values represented by the
getFirstDayOfWeek
, getMinimalDaysInFirstWeek
and
getTimeZone
methods. If there is any difference in those parameters between the two
Calendar
s, this method returns false
.
Use the compareTo
method to compare only the time values.
equals
in class Object
obj
- the object to compare with.true
if this object is equal to obj
; false
otherwise.Object.hashCode()
,
HashMap
public int get(int field)
complete()
method, which process
is calendar system dependent.field
- the given calendar field.ArrayIndexOutOfBoundsException
- if the specified field is out of range (
field < 0 || field >= FIELD_COUNT
).set(int,int)
,
complete()
public int getActualMaximum(int field)
Calendar
. For example, the actual maximum value of the MONTH
field
is 12 in some years, and 13 in other years in the Hebrew calendar system.
The default implementation of this method uses an iterative algorithm to determine the actual maximum value for the calendar field. Subclasses should, if possible, override this with a more efficient implementation.
field
- the calendar fieldCalendar
getMinimum(int)
,
getMaximum(int)
,
getGreatestMinimum(int)
,
getLeastMaximum(int)
,
getActualMinimum(int)
public int getActualMinimum(int field)
Calendar
.
The default implementation of this method uses an iterative algorithm to determine the actual
minimum value for the calendar field. Subclasses should, if possible, override this with a more
efficient implementation - in many cases, they can simply return getMinimum()
.
field
- the calendar fieldCalendar
getMinimum(int)
,
getMaximum(int)
,
getGreatestMinimum(int)
,
getLeastMaximum(int)
,
getActualMaximum(int)
public int getFirstDayOfWeek()
SUNDAY
in the U.S.,
MONDAY
in France.setFirstDayOfWeek(int)
,
getMinimalDaysInFirstWeek()
public abstract int getGreatestMinimum(int field)
Calendar
instance. The highest minimum value is defined as the largest value returned by
getActualMinimum(int)
for any possible time value. The greatest minimum value depends on
calendar system specific parameters of the instance.field
- the calendar field.getMinimum(int)
,
getMaximum(int)
,
getLeastMaximum(int)
,
getActualMinimum(int)
,
getActualMaximum(int)
public static Calendar getInstance()
Calendar
returned is
based on the current time in the default time zone with the default locale.public static Calendar getInstance(TimeZone zone)
Calendar
returned is based on the current time in the given time zone with the default locale.zone
- the time zone to usepublic abstract int getLeastMaximum(int field)
Calendar
instance. The lowest maximum value is defined as the smallest value returned by
getActualMaximum(int)
for any possible time value. The least maximum value depends on
calendar system specific parameters of the instance. For example, a Calendar
for the
Gregorian calendar system returns 28 for the DAY_OF_MONTH
field, because the 28th is
the last day of the shortest month of this calendar, February in a common year.field
- the calendar field.getMinimum(int)
,
getMaximum(int)
,
getGreatestMinimum(int)
,
getActualMinimum(int)
,
getActualMaximum(int)
public abstract int getMaximum(int field)
Calendar
instance.
The maximum value is defined as the largest value returned by the get
method
for any possible time value. The maximum value depends on calendar system specific parameters of
the instance.field
- the calendar field.getMinimum(int)
,
getGreatestMinimum(int)
,
getLeastMaximum(int)
,
getActualMinimum(int)
,
getActualMaximum(int)
public int getMinimalDaysInFirstWeek()
setMinimalDaysInFirstWeek(int)
public abstract int getMinimum(int field)
Calendar
instance.
The minimum value is defined as the smallest value returned by the get
method
for any possible time value. The minimum value depends on calendar system specific parameters of
the instance.field
- the calendar field.getMaximum(int)
,
getGreatestMinimum(int)
,
getLeastMaximum(int)
,
getActualMinimum(int)
,
getActualMaximum(int)
public final Date getTime()
Date
representing the time value.setTime(Date)
,
getTimeInMillis()
public long getTimeInMillis()
getTime()
,
setTimeInMillis(long)
public TimeZone getTimeZone()
public int hashCode()
hashCode
in class Object
Object.equals(java.lang.Object)
,
System.identityHashCode(java.lang.Object)
protected final int internalGet(int field)
field
- the given calendar field.get(int)
public final boolean isSet(int field)
get
method call.field
- the calendar field to testtrue
if the given calendar field has a value set;
false
otherwise.public void set(int field, int value)
field
- the given calendar field.value
- the value to be set for the given calendar field.ArrayIndexOutOfBoundsException
- if the specified field is out of range (
field < 0 || field >= FIELD_COUNT
).set(int,int,int)
,
set(int,int,int,int,int)
,
set(int,int,int,int,int,int)
,
get(int)
public final void set(int year, int month, int date)
YEAR
, MONTH
, and
DAY_OF_MONTH
. Previous values of other calendar fields are retained. If this is not
desired, call clear()
first.year
- the value used to set the YEAR
calendar field.month
- the value used to set the MONTH
calendar field. Month value is 0-based. e.g.,
0 for January.date
- the value used to set the DAY_OF_MONTH
calendar field.set(int,int)
,
set(int,int,int,int,int)
,
set(int,int,int,int,int,int)
public final void set(int year, int month, int date, int hourOfDay, int minute)
YEAR
, MONTH
,
DAY_OF_MONTH
, HOUR_OF_DAY
, and MINUTE
. Previous values of
other fields are retained. If this is not desired, call clear()
first.year
- the value used to set the YEAR
calendar field.month
- the value used to set the MONTH
calendar field. Month value is 0-based. e.g.,
0 for January.date
- the value used to set the DAY_OF_MONTH
calendar field.hourOfDay
- the value used to set the HOUR_OF_DAY
calendar field.minute
- the value used to set the MINUTE
calendar field.set(int,int)
,
set(int,int,int)
,
set(int,int,int,int,int,int)
public final void set(int year, int month, int date, int hourOfDay, int minute, int second)
YEAR
, MONTH
, DAY_OF_MONTH
,
HOUR
, MINUTE
, and SECOND
. Previous values of other fields
are retained. If this is not desired, call clear()
first.year
- the value used to set the YEAR
calendar field.month
- the value used to set the MONTH
calendar field. Month value is 0-based. e.g.,
0 for January.date
- the value used to set the DAY_OF_MONTH
calendar field.hourOfDay
- the value used to set the HOUR_OF_DAY
calendar field.minute
- the value used to set the MINUTE
calendar field.second
- the value used to set the SECOND
calendar field.set(int,int)
,
set(int,int,int)
,
set(int,int,int,int,int)
public void setFirstDayOfWeek(int value)
SUNDAY
in the U.S.,
MONDAY
in France.value
- the given first day of the week.getFirstDayOfWeek()
,
getMinimalDaysInFirstWeek()
public void setMinimalDaysInFirstWeek(int value)
value
- the given minimal days required in the first week of the year.getMinimalDaysInFirstWeek()
public final void setTime(Date date)
Date
.
Note: Calling setTime()
with Date(Long.MAX_VALUE)
or
Date(Long.MIN_VALUE)
may yield incorrect field values from get()
.
date
- the given Date.getTime()
,
setTimeInMillis(long)
public void setTimeInMillis(long millis)
millis
- the new time in UTC milliseconds from the epoch.setTime(Date)
,
getTimeInMillis()
public void setTimeZone(TimeZone value)
value
- the given time zone.public String toString()
null
.