Class SimpleDateFormat

java.lang.Object
java.text.Format
java.text.DateFormat
java.text.SimpleDateFormat
All Implemented Interfaces:
Serializable,Cloneable
public classSimpleDateFormatextendsDateFormat
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 eithergetTimeInstance,getDateInstance, orgetDateTimeInstance inDateFormat. Each of these class methods can return a date/time formatter initialized with a default format pattern. You may modify the format pattern using theapplyPattern methods as desired. For more information on using these methods, seeDateFormat.

Date and Time Patterns

Date and time formats are specified bydate 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):

Chart shows pattern letters, date/time component, presentation, and examples.
LetterDate or Time ComponentPresentationExamples
GEra designatorTextAD
yYearYear1996;96
YWeek yearYear2009;09
MMonth in year (context sensitive)MonthJuly;Jul;07
LMonth in year (standalone form)MonthJuly;Jul;07
wWeek in yearNumber27
WWeek in monthNumber2
DDay in yearNumber189
dDay in monthNumber10
FDay of week in monthNumber2
EDay name in weekTextTuesday;Tue
uDay number of week (1 = Monday, ..., 7 = Sunday)Number1
aAm/pm markerTextPM
HHour in day (0-23)Number0
kHour in day (1-24)Number24
KHour in am/pm (0-11)Number0
hHour in am/pm (1-12)Number12
mMinute in hourNumber30
sSecond in minuteNumber55
SMillisecondNumber978
zTime zoneGeneral time zonePacific Standard Time;PST;GMT-08:00
ZTime zoneRFC 822 time zone-0800
XTime zoneISO 8601 time zone-08;-0800;-08:00
Pattern letters are usually repeated, as their number determines the exact presentation:
  • 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'sCalendar 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 anumber.
    • 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.
    Otherwise, calendar system specific forms are applied. For both formatting and parsing, if the number of pattern letters is 4 or more, a calendar specificlong form is used. Otherwise, a calendar specificshort or abbreviated form is used.

    If week year'Y' is specified and thecalendar 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 astext; otherwise, it is interpreted as anumber.
    • LetterM produces context-sensitive month names, such as the embedded form of names. LetterM 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 aDateFormatSymbols has been set explicitly with constructorSimpleDateFormat(String,DateFormatSymbols) or methodsetDateFormatSymbols(DateFormatSymbols), the month names given by theDateFormatSymbols are used.
    • LetterL produces the standalone form of month names.

  • General time zone: Time zones are interpreted astext if they have names. For time zones representing a GMT offset value, the following syntax is used:
    GMTOffsetTimeZone:GMTSignHours:MinutesSign: one of+ -Hours:DigitDigitDigitMinutes:DigitDigitDigit: one of0 1 2 3 4 5 6 7 8 9
    Hours must be between 0 and 23, andMinutes 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.

    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:SignTwoDigitHoursMinutesTwoDigitHours:Digit Digit
    TwoDigitHours must be between 00 and 23. Other definitions are as forgeneral 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:OneLetterISO8601TimeZoneTwoLetterISO8601TimeZoneThreeLetterISO8601TimeZoneOneLetterISO8601TimeZone:SignTwoDigitHoursZTwoLetterISO8601TimeZone:SignTwoDigitHoursMinutesZThreeLetterISO8601TimeZone:SignTwoDigitHours:MinutesZ
    Other definitions are as forgeneral time zones orRFC 822 time zones.

    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 arenot accepted.

    If the number of pattern letters is 4 or more,IllegalArgumentException is thrown when constructing a SimpleDateFormat orapplying a pattern.

SimpleDateFormat also supportslocalized 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.
Examples of date and time patterns interpreted in the U.S. locale
Date and Time PatternResult
"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 usingDateTimeFormatter as an immutable and thread-safe alternative.
Since:
1.1
See Also:

  • 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

      public SimpleDateFormat(String pattern)
      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 callingSimpleDateFormat(pattern, Locale.getDefault(Locale.Category.FORMAT)).

      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
      See Also:

    • SimpleDateFormat

      public SimpleDateFormat(String pattern,Locale locale)
      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 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

    • SimpleDateFormat

      public SimpleDateFormat(String pattern,DateFormatSymbols formatSymbols)
      Constructs aSimpleDateFormat 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

  • Method Details

    • set2DigitYearStart

      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 rangestartDate tostartDate + 100 years.
      Throws:
      NullPointerException - ifstartDate isnull.
      Since:
      1.2
      See Also:

    • get2DigitYearStart

      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
      Since:
      1.2
      See Also:

    • format

      public StringBuffer format(Date date,StringBuffer toAppendTo,FieldPosition pos)
      Formats the givenDate into a date/time string and appends the result to the givenStringBuffer.
      Specified by:
      format in class DateFormat
      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

      public AttributedCharacterIterator formatToCharacterIterator(Object obj)
      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 typeDateFormat.Field, with the corresponding attribute value being the same as the attribute key.

      Overrides:
      formatToCharacterIterator in class Format
      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

      public Date parse(String text,ParsePosition pos)
      Parses text from a string to produce aDate.

      The method attempts to parse text starting at the index given bypos. 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 thecalendar to produce aDate. All of the calendar's date-time fields arecleared 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. The TimeZone value may be overwritten, depending on the given pattern and the time zone value intext. Any TimeZone value that has previously been set by a call tosetTimeZone may need to be restored for further operations.

      Specified by:
      parse in class DateFormat
      Parameters:
      text - AString, part of which should be parsed.
      pos - AParsePosition object with index and error index information as described above.
      Returns:
      ADate parsed from the string. In case of error, returns null.
      Throws:
      NullPointerException - iftext orpos is null.

    • toPattern

      public String toPattern()
      Returns a pattern string describing this date format.
      Returns:
      a pattern string describing this date format.

    • toLocalizedPattern

      public String toLocalizedPattern()
      Returns a localized pattern string describing this date format.
      Returns:
      a localized pattern string describing this date format.

    • applyPattern

      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

    • applyLocalizedPattern

      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

    • getDateFormatSymbols

      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
      See Also:

    • setDateFormatSymbols

      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:

    • clone

      public Object clone()
      Creates a copy of thisSimpleDateFormat. This also clones the format's date format symbols.
      Overrides:
      clone in class DateFormat
      Returns:
      a clone of thisSimpleDateFormat
      See Also:

    • hashCode

      public int hashCode()
      Returns the hash code value for thisSimpleDateFormat.
      Overrides:
      hashCode in class DateFormat
      Implementation Requirements:
      This method calculates the hash code value using the value returned bytoPattern().
      Returns:
      the hash code value for thisSimpleDateFormat
      See Also:

    • toString

      public String toString()
      Returns a string identifying thisSimpleDateFormat, for debugging.
      Overrides:
      toString in class Object
      Returns:
      a string identifying thisSimpleDateFormat, for debugging

    • equals

      public boolean equals(Object obj)
      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 class DateFormat
      Implementation Requirements:
      This method performs an equality check with a notion of class identity based ongetClass(), 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: