Class SimpleDateFormat
- All Implemented Interfaces:
Serializable
,Cloneable
SimpleDateFormat
is a concrete class for formatting and
parsing dates in a locale-sensitive manner. It allows for formatting
(date → text), parsing (text → date), and normalization.
SimpleDateFormat
allows you to start by choosing
any user-defined patterns for date-time formatting. However, you
are encouraged to create a date-time formatter with either
getTimeInstance
, getDateInstance
, or
getDateTimeInstance
in DateFormat
. Each
of these class methods can return a date/time formatter initialized
with a default format pattern. You may modify the format pattern
using the applyPattern
methods as desired.
For more information on using these methods, see
DateFormat
.
Date and Time Patterns
Date and time formats are specified by date and time pattern
strings.
Within date and time pattern strings, unquoted letters from
'A'
to 'Z'
and from 'a'
to
'z'
are interpreted as pattern letters representing the
components of a date or time string.
Text can be quoted using single quotes ('
) to avoid
interpretation.
"''"
represents a single quote.
All other characters are not interpreted; they're simply copied into the
output string during formatting or matched against the input string
during parsing.
The following pattern letters are defined (all other characters from
'A'
to 'Z'
and from 'a'
to
'z'
are reserved):
Pattern letters are usually repeated, as their number determines the exact presentation:
Letter Date or Time Component Presentation Examples G
Era designator Text AD
y
Year Year 1996
;96
Y
Week year Year 2009
;09
M
Month in year (context sensitive) Month July
;Jul
;07
L
Month in year (standalone form) Month July
;Jul
;07
w
Week in year Number 27
W
Week in month Number 2
D
Day in year Number 189
d
Day in month Number 10
F
Day of week in month Number 2
E
Day name in week Text Tuesday
;Tue
u
Day number of week (1 = Monday, ..., 7 = Sunday) Number 1
a
Am/pm marker Text PM
H
Hour in day (0-23) Number 0
k
Hour in day (1-24) Number 24
K
Hour in am/pm (0-11) Number 0
h
Hour in am/pm (1-12) Number 12
m
Minute in hour Number 30
s
Second in minute Number 55
S
Millisecond Number 978
z
Time zone General time zone Pacific Standard Time
;PST
;GMT-08:00
Z
Time zone RFC 822 time zone -0800
X
Time zone ISO 8601 time zone -08
;-0800
;-08:00
- Text:
For formatting, if the number of pattern letters is 4 or more,
the full form is used; otherwise a short or abbreviated form
is used if available.
For parsing, both forms are accepted, independent of the number
of pattern letters.
- Number:
For formatting, the number of pattern letters is the minimum
number of digits, and shorter numbers are zero-padded to this amount.
For parsing, the number of pattern letters is ignored unless
it's needed to separate two adjacent fields.
- Year:
If the formatter's
Calendar
is the Gregorian calendar, the following rules are applied.
- For formatting, if the number of pattern letters is 2, the year is truncated to 2 digits; otherwise it is interpreted as a number.
- For parsing, if the number of pattern letters is more than 2, the year is interpreted literally, regardless of the number of digits. So using the pattern "MM/dd/yyyy", "01/11/12" parses to Jan 11, 12 A.D.
- For parsing with the abbreviated year pattern ("y" or "yy"),
SimpleDateFormat
must interpret the abbreviated year relative to some century. It does this by adjusting dates to be within 80 years before and 20 years after the time theSimpleDateFormat
instance is created. For example, using a pattern of "MM/dd/yy" and aSimpleDateFormat
instance created on Jan 1, 1997, the string "01/11/12" would be interpreted as Jan 11, 2012 while the string "05/04/64" would be interpreted as May 4, 1964. During parsing, only strings consisting of exactly two digits, as defined byCharacter.isDigit(char)
, will be parsed into the default century. Any other numeric string, such as a one digit string, a three or more digit string, or a two digit string that isn't all digits (for example, "-1"), is interpreted literally. So "01/02/3" or "01/02/003" are parsed, using the same pattern, as Jan 2, 3 AD. Likewise, "01/02/-3" is parsed as Jan 2, 4 BC.
If week year'Y'
is specified and the calendar doesn't support any week years, the calendar year ('y'
) is used instead. The support of week years can be tested with a call togetCalendar()
.isWeekDateSupported()
. - Month:
If the number of pattern letters is 3 or more, the month is
interpreted as text; otherwise,
it is interpreted as a number.
- Letter M produces context-sensitive month names, such as the
embedded form of names. Letter M is context-sensitive in the
sense that when it is used in the standalone pattern, for example,
"MMMM", it gives the standalone form of a month name and when it is
used in the pattern containing other field(s), for example, "d MMMM",
it gives the format form of a month name. For example, January in the
Catalan language is "de gener" in the format form while it is "gener"
in the standalone form. In this case, "MMMM" will produce "gener" and
the month part of the "d MMMM" will produce "de gener". If a
DateFormatSymbols
has been set explicitly with constructorSimpleDateFormat(String,DateFormatSymbols)
or methodsetDateFormatSymbols(DateFormatSymbols)
, the month names given by theDateFormatSymbols
are used. - Letter L produces the standalone form of month names.
- Letter M produces context-sensitive month names, such as the
embedded form of names. Letter M is context-sensitive in the
sense that when it is used in the standalone pattern, for example,
"MMMM", it gives the standalone form of a month name and when it is
used in the pattern containing other field(s), for example, "d MMMM",
it gives the format form of a month name. For example, January in the
Catalan language is "de gener" in the format form while it is "gener"
in the standalone form. In this case, "MMMM" will produce "gener" and
the month part of the "d MMMM" will produce "de gener". If a
- General time zone:
Time zones are interpreted as text if they have
names. For time zones representing a GMT offset value, the
following syntax is used:
GMTOffsetTimeZone:
Hours must be between 0 and 23, and Minutes must be between 00 and 59. The format is locale independent and digits must be taken from the Basic Latin block of the Unicode standard.GMT
Sign Hours:
Minutes Sign: one of+ -
Hours: Digit Digit Digit Minutes: Digit Digit Digit: one of0 1 2 3 4 5 6 7 8 9
For parsing, RFC 822 time zones are also accepted.
- RFC 822 time zone:
For formatting, the RFC 822 4-digit time zone format is used:
RFC822TimeZone: Sign TwoDigitHours Minutes TwoDigitHours: Digit Digit
TwoDigitHours must be between 00 and 23. Other definitions are as for general time zones.For parsing, general time zones are also accepted.
- ISO 8601 Time zone:
The number of pattern letters designates the format for both formatting
and parsing as follows:
ISO8601TimeZone: OneLetterISO8601TimeZone TwoLetterISO8601TimeZone ThreeLetterISO8601TimeZone OneLetterISO8601TimeZone: Sign TwoDigitHours
Other definitions are as for general time zones or RFC 822 time zones.Z
TwoLetterISO8601TimeZone: Sign TwoDigitHours MinutesZ
ThreeLetterISO8601TimeZone: Sign TwoDigitHours:
MinutesZ
For formatting, if the offset value from GMT is 0,
"Z"
is produced. If the number of pattern letters is 1, any fraction of an hour is ignored. For example, if the pattern is"X"
and the time zone is"GMT+05:30"
,"+05"
is produced.For parsing,
"Z"
is parsed as the UTC time zone designator. General time zones are not accepted.If the number of pattern letters is 4 or more,
IllegalArgumentException
is thrown when constructing aSimpleDateFormat
or applying a pattern.
SimpleDateFormat
also supports localized date and time
pattern strings. In these strings, the pattern letters described above
may be replaced with other, locale dependent, pattern letters.
SimpleDateFormat
does not deal with the localization of text
other than the pattern letters; that's up to the client of the class.
Examples
The following examples show how date and time patterns are interpreted in the U.S. locale. The given date and time are 2001-07-04 12:08:56 local time in the U.S. Pacific Time time zone.
Date and Time Pattern Result "yyyy.MM.dd G 'at' HH:mm:ss z"
2001.07.04 AD at 12:08:56 PDT
"EEE, MMM d, ''yy"
Wed, Jul 4, '01
"h:mm a"
12:08 PM
"hh 'o''clock' a, zzzz"
12 o'clock PM, Pacific Daylight Time
"K:mm a, z"
0:08 PM, PDT
"yyyyy.MMMMM.dd GGG hh:mm aaa"
02001.July.04 AD 12:08 PM
"EEE, d MMM yyyy HH:mm:ss Z"
Wed, 4 Jul 2001 12:08:56 -0700
"yyMMddHHmmssZ"
010704120856-0700
"yyyy-MM-dd'T'HH:mm:ss.SSSZ"
2001-07-04T12:08:56.235-0700
"yyyy-MM-dd'T'HH:mm:ss.SSSXXX"
2001-07-04T12:08:56.235-07:00
"YYYY-'W'ww-u"
2001-W27-3
Synchronization
Date formats are not synchronized. It is recommended to create separate format instances for each thread. If multiple threads access a format concurrently, it must be synchronized externally.
- API Note:
- Consider using
DateTimeFormatter
as an immutable and thread-safe alternative. - Since:
- 1.1
- See Also:
-
Nested Class Summary
Nested classes/interfaces inherited from class java.text.DateFormat
DateFormat.Field
-
Field Summary
Fields inherited from class java.text.DateFormat
AM_PM_FIELD, calendar, DATE_FIELD, DAY_OF_WEEK_FIELD, DAY_OF_WEEK_IN_MONTH_FIELD, DAY_OF_YEAR_FIELD, DEFAULT, ERA_FIELD, FULL, HOUR_OF_DAY0_FIELD, HOUR_OF_DAY1_FIELD, HOUR0_FIELD, HOUR1_FIELD, LONG, MEDIUM, MILLISECOND_FIELD, MINUTE_FIELD, MONTH_FIELD, numberFormat, SECOND_FIELD, SHORT, TIMEZONE_FIELD, WEEK_OF_MONTH_FIELD, WEEK_OF_YEAR_FIELD, YEAR_FIELD
-
Constructor Summary
ConstructorDescriptionConstructs aSimpleDateFormat
using the default pattern and date format symbols for the defaultFORMAT
locale.SimpleDateFormat
(String pattern) Constructs aSimpleDateFormat
using the given pattern and the default date format symbols for the defaultFORMAT
locale.SimpleDateFormat
(String pattern, DateFormatSymbols formatSymbols) Constructs aSimpleDateFormat
using the given pattern and date format symbols.SimpleDateFormat
(String pattern, Locale locale) Constructs aSimpleDateFormat
using the given pattern and the default date format symbols for the given locale. -
Method Summary
Modifier and TypeMethodDescriptionvoid
applyLocalizedPattern
(String pattern) Applies the given localized pattern string to this date format.void
applyPattern
(String pattern) Applies the given pattern string to this date format.clone()
Creates a copy of thisSimpleDateFormat
.boolean
Compares the specified object with thisSimpleDateFormat
for equality.format
(Date date, StringBuffer toAppendTo, FieldPosition pos) Formats the givenDate
into a date/time string and appends the result to the givenStringBuffer
.Formats an Object producing anAttributedCharacterIterator
.Returns the beginning date of the 100-year period 2-digit years are interpreted as being within.Gets a copy of the date and time format symbols of this date format.int
hashCode()
Returns the hash code value for thisSimpleDateFormat
.parse
(String text, ParsePosition pos) Parses text from a string to produce aDate
.void
set2DigitYearStart
(Date startDate) Sets the 100-year period 2-digit years will be interpreted as being in to begin on the date the user specifies.void
setDateFormatSymbols
(DateFormatSymbols newFormatSymbols) Sets the date and time format symbols of this date format.Returns a localized pattern string describing this date format.Returns a pattern string describing this date format.toString()
Returns a string identifying thisSimpleDateFormat
, for debugging.Methods inherited from class java.text.DateFormat
format, format, getAvailableLocales, getCalendar, getDateInstance, getDateInstance, getDateInstance, getDateTimeInstance, getDateTimeInstance, getDateTimeInstance, getInstance, getNumberFormat, getTimeInstance, getTimeInstance, getTimeInstance, getTimeZone, isLenient, parse, parseObject, setCalendar, setLenient, setNumberFormat, setTimeZone
Methods inherited from class java.text.Format
format, parseObject
-
Constructor Details
-
SimpleDateFormat
public SimpleDateFormat()Constructs aSimpleDateFormat
using the default pattern and date format symbols for the defaultFORMAT
locale. Note: This constructor may not support all locales. For full coverage, use the factory methods in theDateFormat
class. -
SimpleDateFormat
Constructs aSimpleDateFormat
using the given pattern and the default date format symbols for the defaultFORMAT
locale. Note: This constructor may not support all locales. For full coverage, use the factory methods in theDateFormat
class.This is equivalent to calling
SimpleDateFormat(pattern, Locale.getDefault(Locale.Category.FORMAT))
.- Parameters:
pattern
- the pattern describing the date and time format- Throws:
NullPointerException
- if the given pattern is nullIllegalArgumentException
- if the given pattern is invalid- See Also:
-
SimpleDateFormat
Constructs aSimpleDateFormat
using the given pattern and the default date format symbols for the given locale. Note: This constructor may not support all locales. For full coverage, use the factory methods in theDateFormat
class.- Parameters:
pattern
- the pattern describing the date and time formatlocale
- the locale whose date format symbols should be used- Throws:
NullPointerException
- if the given pattern or locale is nullIllegalArgumentException
- if the given pattern is invalid
-
SimpleDateFormat
Constructs aSimpleDateFormat
using the given pattern and date format symbols.- Parameters:
pattern
- the pattern describing the date and time formatformatSymbols
- the date format symbols to be used for formatting- Throws:
NullPointerException
- if the given pattern or formatSymbols is nullIllegalArgumentException
- if the given pattern is invalid
-
-
Method Details
-
set2DigitYearStart
Sets the 100-year period 2-digit years will be interpreted as being in to begin on the date the user specifies.- Parameters:
startDate
- During parsing, two digit years will be placed in the rangestartDate
tostartDate + 100 years
.- Throws:
NullPointerException
- ifstartDate
isnull
.- Since:
- 1.2
- See Also:
-
get2DigitYearStart
Returns the beginning date of the 100-year period 2-digit years are interpreted as being within.- Returns:
- the start of the 100-year period into which two digit years are parsed
- Since:
- 1.2
- See Also:
-
format
Formats the givenDate
into a date/time string and appends the result to the givenStringBuffer
.- Specified by:
format
in classDateFormat
- Parameters:
date
- the date-time value to be formatted into a date-time string.toAppendTo
- where the new date-time text is to be appended.pos
- keeps track on the position of the field within the returned string. For example, given a date-time text"1996.07.10 AD at 15:08:56 PDT"
, if the givenfieldPosition
isDateFormat.YEAR_FIELD
, the begin index and end index offieldPosition
will be set to 0 and 4, respectively. Notice that if the same date-time field appears more than once in a pattern, thefieldPosition
will be set for the first occurrence of that date-time field. For instance, formatting aDate
to the date-time string"1 PM PDT (Pacific Daylight Time)"
using the pattern"h a z (zzzz)"
and the alignment fieldDateFormat.TIMEZONE_FIELD
, the begin index and end index offieldPosition
will be set to 5 and 8, respectively, for the first occurrence of the timezone pattern character'z'
.- Returns:
- the formatted date-time string.
- Throws:
NullPointerException
- if any of the parameters isnull
.
-
formatToCharacterIterator
Formats an Object producing anAttributedCharacterIterator
. You can use the returnedAttributedCharacterIterator
to build the resulting String, as well as to determine information about the resulting String.Each attribute key of the AttributedCharacterIterator will be of type
DateFormat.Field
, with the corresponding attribute value being the same as the attribute key.- Overrides:
formatToCharacterIterator
in classFormat
- Parameters:
obj
- The object to format- Returns:
- AttributedCharacterIterator describing the formatted value.
- Throws:
NullPointerException
- if obj is null.IllegalArgumentException
- if the Format cannot format the given object, or if the Format's pattern string is invalid.- Since:
- 1.4
-
parse
Parses text from a string to produce aDate
.The method attempts to parse text starting at the index given by
pos
. If parsing succeeds, then the index ofpos
is updated to the index after the last character used (parsing does not necessarily use all characters up to the end of the string), and the parsed date is returned. The updatedpos
can be used to indicate the starting point for the next call to this method. If an error occurs, then the index ofpos
is not changed, the error index ofpos
is set to the index of the character where the error occurred, and null is returned.This parsing operation uses the
calendar
to produce aDate
. All of thecalendar
's date-time fields are cleared before parsing, and thecalendar
's default values of the date-time fields are used for any missing date-time information. For example, the year value of the parsedDate
is 1970 withGregorianCalendar
if no year value is given from the parsing operation. TheTimeZone
value may be overwritten, depending on the given pattern and the time zone value intext
. AnyTimeZone
value that has previously been set by a call tosetTimeZone
may need to be restored for further operations.- Specified by:
parse
in classDateFormat
- Parameters:
text
- AString
, part of which should be parsed.pos
- AParsePosition
object with index and error index information as described above.- Returns:
- A
Date
parsed from the string. In case of error, returns null. - Throws:
NullPointerException
- iftext
orpos
is null.
-
toPattern
Returns a pattern string describing this date format.- Returns:
- a pattern string describing this date format.
-
toLocalizedPattern
Returns a localized pattern string describing this date format.- Returns:
- a localized pattern string describing this date format.
-
applyPattern
Applies the given pattern string to this date format.- Parameters:
pattern
- the new date and time pattern for this date format- Throws:
NullPointerException
- if the given pattern is nullIllegalArgumentException
- if the given pattern is invalid
-
applyLocalizedPattern
Applies the given localized pattern string to this date format.- Parameters:
pattern
- a String to be mapped to the new date and time format pattern for this format- Throws:
NullPointerException
- if the given pattern is nullIllegalArgumentException
- if the given pattern is invalid
-
getDateFormatSymbols
Gets a copy of the date and time format symbols of this date format.- Returns:
- the date and time format symbols of this date format
- See Also:
-
setDateFormatSymbols
Sets the date and time format symbols of this date format.- Parameters:
newFormatSymbols
- the new date and time format symbols- Throws:
NullPointerException
- if the given newFormatSymbols is null- See Also:
-
clone
Creates a copy of thisSimpleDateFormat
. This also clones the format's date format symbols.- Overrides:
clone
in classDateFormat
- Returns:
- a clone of this
SimpleDateFormat
- See Also:
-
hashCode
public int hashCode()Returns the hash code value for thisSimpleDateFormat
.- Overrides:
hashCode
in classDateFormat
- Implementation Requirements:
- This method calculates the hash code value using the value returned by
toPattern()
. - Returns:
- the hash code value for this
SimpleDateFormat
- See Also:
-
toString
-
equals
Compares the specified object with thisSimpleDateFormat
for equality. Returns true if the object is also aSimpleDateFormat
and the two formats would format any value the same.- Overrides:
equals
in classDateFormat
- Implementation Requirements:
- This method performs an equality check with a notion of class
identity based on
getClass()
, rather thaninstanceof
. Therefore, in the equals methods in subclasses, no instance of this class should compare as equal to an instance of a subclass. - Parameters:
obj
- object to be compared for equality- Returns:
true
if the specified object is equal to thisSimpleDateFormat
- See Also:
-