SimpleDateFormat

Class Overview

A concrete class for formatting and parsing dates in a locale-sensitive manner. It allows for formatting (date to text), parsing (text to 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.

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 follows:

Symbol	Meaning	Presentation	Example
G	era designator	(Text)	AD
y	year	(Number)	1996
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
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
V	time zone (location)	(Text)	United States (Los Angeles)
'	escape for text	(Delimiter)	'Date='
''	single quote	(Literal)	'o''clock'

The count of pattern letters determines the format:

(Text): 4 or more pattern letters → use the full form, less than 4 pattern letters → use a 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. (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 an exception thrown 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
 

Code Sample:

 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);
 

In the example, the time value currentTime_2 obtained from parsing will be equal to currentTime_1. However, they may not be equal if the am/pm marker 'a' is left out from the format pattern while the "hour in am/pm" pattern symbol is used. This information loss can happen when formatting the time in PM.

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 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 are adjacent directly, with no intervening delimiter characters, they constitute a run of adjacent 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 the strings "GMT+hours:minutes" or "GMT-hours:minutes".

The calendar defines 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

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.

Summary

[Expand] Inherited Constants

From class java.text.DateFormat int AM_PM_FIELD FieldPosition selector for 'a' field alignment, corresponds to the AM_PM field. int DATE_FIELD The FieldPosition selector for 'd' field alignment, corresponds to the DATE field. int DAY_OF_WEEK_FIELD FieldPosition selector for 'E' field alignment, corresponds to the DAY_OF_WEEK field. int DAY_OF_WEEK_IN_MONTH_FIELD FieldPosition selector for 'F' field alignment, corresponds to the DAY_OF_WEEK_IN_MONTH field. int DAY_OF_YEAR_FIELD FieldPosition selector for 'D' field alignment, corresponds to the DAY_OF_YEAR field. int DEFAULT The format style constant defining the default format style. int ERA_FIELD The FieldPosition selector for 'G' field alignment, corresponds to the ERA field. int FULL The format style constant defining the full style. int HOUR0_FIELD The FieldPosition selector for 'z' field alignment, corresponds to the ZONE_OFFSET and DST_OFFSET fields. int HOUR1_FIELD FieldPosition selector for 'h' field alignment, corresponding to the HOUR field. int HOUR_OF_DAY0_FIELD The FieldPosition selector for 'H' field alignment, corresponds to the HOUR_OF_DAY field. int HOUR_OF_DAY1_FIELD The FieldPosition selector for 'k' field alignment, corresponds to the HOUR_OF_DAY field. int LONG The format style constant defining the long style. int MEDIUM The format style constant defining the medium style. int MILLISECOND_FIELD FieldPosition selector for 'S' field alignment, corresponds to the MILLISECOND field. int MINUTE_FIELD FieldPosition selector for 'm' field alignment, corresponds to the MINUTE field. int MONTH_FIELD The FieldPosition selector for 'M' field alignment, corresponds to the MONTH field. int SECOND_FIELD FieldPosition selector for 's' field alignment, corresponds to the SECOND field. int SHORT The format style constant defining the short style. int TIMEZONE_FIELD The FieldPosition selector for 'z' field alignment, corresponds to the ZONE_OFFSET and DST_OFFSET fields. int WEEK_OF_MONTH_FIELD FieldPosition selector for 'W' field alignment, corresponds to the WEEK_OF_MONTH field. int WEEK_OF_YEAR_FIELD FieldPosition selector for 'w' field alignment, corresponds to the WEEK_OF_YEAR field. int YEAR_FIELD The FieldPosition selector for 'y' field alignment, corresponds to the YEAR field.

[Expand] Inherited Fields
From class java.text.DateFormat protected Calendar calendar The calendar that this DateFormat uses to format a number representing a date. protected NumberFormat numberFormat The number format used to format a number.

Public Constructors
	SimpleDateFormat() Constructs a new SimpleDateFormat for formatting and parsing dates and times in the SHORT style for the default locale.
	SimpleDateFormat(String pattern) Constructs a new SimpleDateFormat using the specified non-localized pattern and the DateFormatSymbols and Calendar for the default locale.
	SimpleDateFormat(String template, DateFormatSymbols value) Constructs a new SimpleDateFormat using the specified non-localized pattern and DateFormatSymbols and the Calendar for the default locale.
	SimpleDateFormat(String template, Locale locale) Constructs a new SimpleDateFormat using the specified non-localized pattern and the DateFormatSymbols and Calendar for the specified locale.

Public Methods
void	applyLocalizedPattern(String template) Changes the pattern of this simple date format to the specified pattern which uses localized pattern characters.
void	applyPattern(String template) Changes the pattern of this simple date format to the specified pattern which uses non-localized pattern characters.
Object	clone() Returns a new SimpleDateFormat with the same pattern and properties as this simple date format.
boolean	equals(Object object) Compares the specified object with this simple date format and indicates if they are equal.
StringBuffer	format(Date date, StringBuffer buffer, FieldPosition fieldPos) Formats the specified date as a string using the pattern of this date format and appends the string to the specified string buffer.
AttributedCharacterIterator	formatToCharacterIterator(Object object) Formats the specified object using the rules of this simple date format and returns an AttributedCharacterIterator with the formatted date and attributes.
Date	get2DigitYearStart() Answers the Date which is the start of the one hundred year period for two digits year values.
DateFormatSymbols	getDateFormatSymbols() Returns the DateFormatSymbols used by this simple date format.
int	hashCode() Returns an integer hash code for this object.
Date	parse(String string, ParsePosition position) Parses a date from the specified string starting at the index specified by position.
void	set2DigitYearStart(Date date) Sets the date which is the start of the one hundred year period for two digits year values.
void	setDateFormatSymbols(DateFormatSymbols value) Sets the DateFormatSymbols used by this simple date format.
String	toLocalizedPattern() Returns the pattern of this simple date format using localized pattern characters.
String	toPattern() Returns the pattern of this simple date format using non-localized pattern characters.

[Expand] Inherited Methods
From class java.text.DateFormat Object clone() Returns a new instance of DateFormat with the same properties. boolean equals(Object object) Compares this date format with the specified object and indicates if they are equal. final StringBuffer format(Object object, StringBuffer buffer, FieldPosition field) Formats the specified object as a string using the pattern of this date format and appends the string to the specified string buffer. final String format(Date date) Formats the specified date using the rules of this date format. abstract StringBuffer format(Date date, StringBuffer buffer, FieldPosition field) Formats the specified date as a string using the pattern of this date format and appends the string to the specified string buffer. static Locale[] getAvailableLocales() Gets the list of installed locales which support DateFormat. Calendar getCalendar() Returns the calendar used by this DateFormat. final static DateFormat getDateInstance(int style, Locale locale) Returns a DateFormat instance for formatting and parsing dates in the specified style for the specified locale. final static DateFormat getDateInstance() Returns a DateFormat instance for formatting and parsing dates in the DEFAULT style for the default locale. final static DateFormat getDateInstance(int style) Returns a DateFormat instance for formatting and parsing dates in the specified style for the default locale. final static DateFormat getDateTimeInstance(int dateStyle, int timeStyle) Returns a DateFormat instance for formatting and parsing of both dates and time values in the manner appropriate for the default locale. final static DateFormat getDateTimeInstance(int dateStyle, int timeStyle, Locale locale) Returns a DateFormat instance for formatting and parsing dates and time values in the specified styles for the specified locale. final static DateFormat getDateTimeInstance() Returns a DateFormat instance for formatting and parsing dates and time values in the DEFAULT style for the default locale. final static DateFormat getInstance() Returns a DateFormat instance for formatting and parsing dates and times in the SHORT style for the default locale. NumberFormat getNumberFormat() Returns the NumberFormat used by this DateFormat. final static DateFormat getTimeInstance(int style) Returns a DateFormat instance for formatting and parsing time values in the specified style for the default locale. final static DateFormat getTimeInstance() Returns a DateFormat instance for formatting and parsing time values in the DEFAULT style for the default locale. final static DateFormat getTimeInstance(int style, Locale locale) Returns a DateFormat instance for formatting and parsing time values in the specified style for the specified locale. TimeZone getTimeZone() Returns the time zone of this date format's calendar. int hashCode() Returns an integer hash code for this object. boolean isLenient() Indicates whether the calendar used by this date format is lenient. Date parse(String string) Parses a date from the specified string using the rules of this date format. abstract Date parse(String string, ParsePosition position) Parses a date from the specified string starting at the index specified by position. Object parseObject(String string, ParsePosition position) Parses a date from the specified string starting at the index specified by position. void setCalendar(Calendar cal) Sets the calendar used by this date format. void setLenient(boolean value) Specifies whether or not date/time parsing shall be lenient. void setNumberFormat(NumberFormat format) Sets the NumberFormat used by this date format. void setTimeZone(TimeZone timezone) Sets the time zone of the calendar used by this date format.
From class java.text.Format Object clone() Returns a copy of this Format instance. abstract StringBuffer format(Object object, StringBuffer buffer, FieldPosition field) Appends the specified object to the specified string buffer using the rules of this format. final String format(Object object) Formats the specified object using the rules of this format. AttributedCharacterIterator formatToCharacterIterator(Object object) Formats the specified object using the rules of this format and returns an AttributedCharacterIterator with the formatted string and no attributes. abstract Object parseObject(String string, ParsePosition position) Parses the specified string starting at the index specified by position. Object parseObject(String string) Parses the specified string using the rules of this format.
From class java.lang.Object Object clone() Creates and returns a copy of this Object. boolean equals(Object o) Compares this instance with the specified object and indicates if they are equal. void finalize() Is called before the object's memory is being reclaimed by the VM. final Class<? extends Object> getClass() Returns the unique instance of Class which represents this object's class. int hashCode() Returns an integer hash code for this object. final void notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up. final void notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up. String toString() Returns a string containing a concise, human-readable description of this object. final void wait(long millis, int nanos) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires. final void wait(long millis) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires. final void wait() Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object.