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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 .

Time Format Syntax:

To specify the time format use a time pattern string. In this pattern, all ASCII letters are reserved as pattern letters, which are defined as the following:

 Symbol   Meaning                 Presentation        Example
 ------   -------                 ------------        -------
 G        era designator          (Text)              AD
 y†       year                    (Number)            1996
 Y*       year (week of year)     (Number)            1997
 u*       extended year           (Number)            4601
 M        month in year           (Text & Number)     July & 07
 d        day in month            (Number)            10
 h        hour in am/pm (1~12)    (Number)            12
 H        hour in day (0~23)      (Number)            0
 m        minute in hour          (Number)            30
 s        second in minute        (Number)            55
 S        fractional second       (Number)            978
 E        day of week             (Text)              Tuesday
 e*       day of week (local 1~7) (Number)            2
 D        day in year             (Number)            189
 F        day of week in month    (Number)            2 (2nd Wed in July)
 w        week in year            (Number)            27
 W        week in month           (Number)            2
 a        am/pm marker            (Text)              PM
 k        hour in day (1~24)      (Number)            24
 K        hour in am/pm (0~11)    (Number)            0
 z        time zone               (Text)              Pacific Standard Time
 Z        time zone (RFC 822)     (Number)            -0800
 v        time zone (generic)     (Text)              Pacific Time
 g*       Julian day              (Number)            2451334
 A*       milliseconds in day     (Number)            69540000
 '        escape for text         (Delimiter)         'Date='
 ''       single quote            (Literal)           'o''clock'
 

The count of pattern letters determine the format.

(Text): 4 or more pattern letters--use full form, < 4--use short or abbreviated form if one exists.

(Number): the minimum number of digits. Shorter numbers are zero-padded to this amount. Year is handled specially; that is, if the count of 'y' is 2, the Year will be truncated to 2 digits. (e.g., if "yyyy" produces "1997", "yy" produces "97".) Unlike other fields, fractional seconds are padded on the right with zero.

(Text & Number): 3 or over, use text, otherwise use number.

Any characters in the pattern that are not in the ranges of ['a'..'z'] and ['A'..'Z'] will be treated as quoted text. For instance, characters like ':', '.', ' ', '#' and '@' will appear in the resulting time text even they are not embraced within single quotes.

A pattern containing any invalid pattern letter will result in a thrown exception during formatting or parsing.

Examples Using the US Locale:

 Format Pattern                         Result
 --------------                         -------
 "yyyy.MM.dd G 'at' HH:mm:ss vvvv" ->>  1996.07.10 AD at 15:08:56 Pacific Time
 "EEE, MMM d, ''yy"                ->>  Wed, July 10, '96
 "h:mm a"                          ->>  12:08 PM
 "hh 'o''clock' a, zzzz"           ->>  12 o'clock PM, Pacific Daylight Time
 "K:mm a, vvv"                     ->>  0:00 PM, PT
 "yyyyy.MMMMM.dd GGG hh:mm aaa"    ->>  01996.July.10 AD 12:08 PM
 

 SimpleTimeZone pdt = new SimpleTimeZone(-8 * 60 * 60 * 1000, "PST");
 pdt.setStartRule(Calendar.APRIL, 1, Calendar.SUNDAY, 2*60*60*1000);
 pdt.setEndRule(Calendar.OCTOBER, -1, Calendar.SUNDAY, 2*60*60*1000);
 

 // Format the current time.
 SimpleDateFormat formatter
 = new SimpleDateFormat ("yyyy.MM.dd G 'at' hh:mm:ss a zzz");
 Date currentTime_1 = new Date();
 String dateString = formatter.format(currentTime_1);
 

 // Parse the previous string back into a Date.
 ParsePosition pos = new ParsePosition(0);
 Date currentTime_2 = formatter.parse(dateString, pos);
 

When parsing a date string using the abbreviated year pattern ("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 the SimpleDateFormat instance is created. For example, using a pattern of "MM/dd/yy" and a SimpleDateFormat 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 by java.lang.Character.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 the year pattern does not have exactly two 'y' characters, 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.

When numeric fields abut one another directly, with no intervening delimiter characters, they constitute a run of abutting numeric fields. Such runs are parsed specially. For example, the format "HHmmss" parses the input text "123456" to 12:34:56, parses the input text "12345" to 1:23:45, and fails to parse "1234". In other words, the leftmost field of the run is flexible, while the others keep a fixed width. If the parse fails anywhere in the run, then the leftmost field is shortened by one character, and the entire run is parsed again. This is repeated until either the parse succeeds or the leftmost field is one character in length. If the parse still fails at that point, the parse of the run fails.

For time zones that have no names, use strings GMT+hours:minutes or GMT-hours:minutes.

The calendar defines what is the first day of the week, the first week of the year, whether hours are zero based or not (0 vs 12 or 24), and the time zone. There is one common decimal format to handle all the numbers; the digit count is handled programmatically according to the pattern.

Synchronization

Formats a date or time, which is the standard millis since January 1, 1970, 00:00:00 GMT.

Example: using the US locale: "yyyy.MM.dd G 'at' HH:mm:ss zzz" ->> 1996.07.10 AD at 15:08:56 PDT
Parameters:
  cal - the calendar whose date-time value is to be formatted into a date-time string
Parameters:
  toAppendTo - where the new date-time text is to be appended
Parameters:
  pos - the formatting position.

Formats a date or time, which is the standard millis since January 1, 1970, 00:00:00 GMT.

Example: using the US locale: "yyyy.MM.dd G 'at' HH:mm:ss zzz" ->> 1996.07.10 AD at 15:08:56 PDT
Parameters:
  cal - the calendar whose date-time value is to be formatted into a date-time string
Parameters:
  toAppendTo - where the new date-time text is to be appended
Parameters:
  pos - the formatting position. On input: an alignment field,if desired. On output: the offsets of the alignment field. the formatted date-time string.
See Also:   DateFormat