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 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 {@linkplain #getCalendar() 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.
- 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:
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.GMTOffsetTimeZone:
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:
TwoDigitHours must be between 00 and 23. Other definitions are as for general time zones.RFC822TimeZone: Sign TwoDigitHours Minutes TwoDigitHours: Digit Digit
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:
Other definitions are as for general time zones or RFC 822 time zones.ISO8601TimeZone: OneLetterISO8601TimeZone TwoLetterISO8601TimeZone ThreeLetterISO8601TimeZone OneLetterISO8601TimeZone: Sign TwoDigitHours
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 {@linkplain #applyPattern(String) 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.MMMM.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.
Inherited Constant Summary
Inherited Field Summary
Public Constructor Summary
SimpleDateFormat()
Constructs a
SimpleDateFormat using the default pattern and
date format symbols for the default locale. |
|
SimpleDateFormat(String pattern)
Constructs a
SimpleDateFormat using the given pattern and
the default date format symbols for the default locale. |
|
SimpleDateFormat(String pattern, Locale locale)
Constructs a
SimpleDateFormat using the given pattern and
the default date format symbols for the given locale. |
|
SimpleDateFormat(String pattern, DateFormatSymbols formatSymbols)
Constructs a
SimpleDateFormat using the given pattern and
date format symbols. |
Public Method Summary
void |
applyLocalizedPattern(String pattern)
Applies the given localized pattern string to this date format.
|
void | |
Object |
clone()
Creates a copy of this
SimpleDateFormat . |
boolean | |
StringBuffer |
format(Date date, StringBuffer toAppendTo, FieldPosition pos)
Formats the given
Date into a date/time string and appends
the result to the given StringBuffer . |
AttributedCharacterIterator | |
Date |
get2DigitYearStart()
Returns the beginning date of the 100-year period 2-digit years are interpreted
as being within.
|
DateFormatSymbols |
getDateFormatSymbols()
Gets a copy of the date and time format symbols of this date format.
|
int |
hashCode()
Returns the hash code value for this
SimpleDateFormat object. |
Date | |
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.
|
String |
toLocalizedPattern()
Returns a localized pattern string describing this date format.
|
String |
toPattern()
Returns a pattern string describing this date format.
|
Inherited Method Summary
Public Constructors
public SimpleDateFormat ()
Constructs a SimpleDateFormat
using the default pattern and
date format symbols for the default locale.
Note: This constructor may not support all locales.
For full coverage, use the factory methods in the DateFormat
class.
public SimpleDateFormat (String pattern)
Constructs a SimpleDateFormat
using the given pattern and
the default date format symbols for the default locale.
Note: This constructor may not support all locales.
For full coverage, use the factory methods in the DateFormat
class.
Parameters
pattern | the pattern describing the date and time format |
---|
Throws
NullPointerException | if the given pattern is null |
---|---|
IllegalArgumentException | if the given pattern is invalid |
public SimpleDateFormat (String pattern, Locale locale)
Constructs a SimpleDateFormat
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 the DateFormat
class.
Parameters
pattern | the pattern describing the date and time format |
---|---|
locale | the locale whose date format symbols should be used |
Throws
NullPointerException | if the given pattern or locale is null |
---|---|
IllegalArgumentException | if the given pattern is invalid |
public SimpleDateFormat (String pattern, DateFormatSymbols formatSymbols)
Constructs a SimpleDateFormat
using the given pattern and
date format symbols.
Parameters
pattern | the pattern describing the date and time format |
---|---|
formatSymbols | the date format symbols to be used for formatting |
Throws
NullPointerException | if the given pattern or formatSymbols is null |
---|---|
IllegalArgumentException | if the given pattern is invalid |
Public Methods
public void applyLocalizedPattern (String pattern)
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 null |
---|---|
IllegalArgumentException | if the given pattern is invalid |
public void applyPattern (String pattern)
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 null |
---|---|
IllegalArgumentException | if the given pattern is invalid |
public Object clone ()
Creates a copy of this SimpleDateFormat
. This also
clones the format's date format symbols.
Returns
- a clone of this
SimpleDateFormat
public boolean equals (Object obj)
Compares the given object with this SimpleDateFormat
for
equality.
Parameters
obj | the object to compare this instance with. |
---|
Returns
- true if the given object is equal to this
SimpleDateFormat
public StringBuffer format (Date date, StringBuffer toAppendTo, FieldPosition pos)
Formats the given Date
into a date/time string and appends
the result to the given StringBuffer
.
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 | the formatting position. On input: an alignment field, if desired. On output: the offsets of the alignment field. |
Returns
- the formatted date-time string.
Throws
NullPointerException | if the given date is null .
|
---|
public AttributedCharacterIterator formatToCharacterIterator (Object obj)
Formats an Object producing an AttributedCharacterIterator
.
You can use the returned AttributedCharacterIterator
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.
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. |
public Date 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
See Also
public DateFormatSymbols 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
public int hashCode ()
Returns the hash code value for this SimpleDateFormat
object.
Returns
- the hash code value for this
SimpleDateFormat
object.
public Date parse (String text, ParsePosition pos)
Parses text from a string to produce a Date
.
The method attempts to parse text starting at the index given by
pos
.
If parsing succeeds, then the index of pos
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 updated pos
can be used to
indicate the starting point for the next call to this method.
If an error occurs, then the index of pos
is not
changed, the error index of pos
is set to the index of
the character where the error occurred, and null is returned.
This parsing operation uses the calendar
to produce a Date
. All of the calendar
's date-time fields are {@linkplain Calendar#clear()
cleared} before parsing, and the calendar
's default
values of the date-time fields are used for any missing
date-time information. For example, the year value of the
parsed Date
is 1970 with GregorianCalendar
if
no year value is given from the parsing operation. The TimeZone
value may be overwritten, depending on the given
pattern and the time zone value in text
. Any TimeZone
value that has previously been set by a call to
setTimeZone
may need
to be restored for further operations.
Parameters
text | A String , part of which should be parsed. |
---|---|
pos | A ParsePosition 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 | if text or pos is null.
|
---|
public 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.
Parameters
startDate | During parsing, two digit years will be placed in the range
startDate to startDate + 100 years . |
---|
See Also
public void setDateFormatSymbols (DateFormatSymbols newFormatSymbols)
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
public String toLocalizedPattern ()
Returns a localized pattern string describing this date format.
Returns
- a localized pattern string describing this date format.
public String toPattern ()
Returns a pattern string describing this date format.
Returns
- a pattern string describing this date format.