Class SimpleDateFormat

  • All Implemented Interfaces:
    Serializable, Cloneable
    Direct Known Subclasses:
    ChineseDateFormat

    public class SimpleDateFormat
    extends DateFormat
    implements Cloneable
    [icu enhancement] ICU's replacement for java.text.SimpleDateFormat. Methods, fields, and other functionality specific to ICU are labeled '[icu]'.

    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.

    Clients are encouraged to create a date-time formatter using DateFormat.getDateInstance(), DateFormat.getDateInstance(), or DateFormat.getDateTimeInstance() rather than explicitly constructing an instance of SimpleDateFormat. This way, the client is guaranteed to get an appropriate formatting pattern for whatever locale the program is running in. If the client needs more control, they should consider using DateFormat.getInstanceForSkeleton(). However, if the client needs something more unusual than the default patterns in the locales, he can construct a SimpleDateFormat directly and give it an appropriate pattern (or use one of the factory methods on DateFormat and modify the pattern after the fact with toPattern() and applyPattern(). 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. The full syntax for date and time patterns can be found at https://unicode.org/reports/tr35/tr35-dates.html#Date_Format_Patterns.

    Within date and time pattern strings, all unquoted ASCII letters [A-Za-z] are reserved as pattern letters representing calendar fields. Some of the most commonly used pattern letters are:

    Sym. No. Example Description
    G 1..3 AD Era - Replaced with the Era string for the current date. One to three letters for the abbreviated form, four letters for the long (wide) form, five for the narrow form.
    y 1..n 1996 Year. Normally the length specifies the padding, but for two letters it also specifies the maximum length. Example:
    Year y yy yyy yyyy yyyyy
    AD 1 1 01 001 0001 00001
    AD 12 12 12 012 0012 00012
    AD 123 123 23 123 0123 00123
    AD 1234 1234 34 1234 1234 01234
    AD 12345 12345 45 12345 12345 12345
    Q 1..2 02 Quarter - Use one or two for the numerical quarter, three for the abbreviation, or four for the full (wide) name (five for the narrow name is not yet supported).
    3 Q2
    4 2nd quarter
    M 1..2 09 Month - Use one or two for the numerical month, three for the abbreviation, four for the full (wide) name, or five for the narrow name. With two ("MM"), the month number is zero-padded if necessary (e.g. "08").
    3 Sep
    4 September
    5 S
    d 1..2 1 Date - Day of the month. Use "d" to show the minimum number of digits, or "dd" to always show two digits (zero-padding if necessary, e.g. "08").
    E 1..3 Tue Day of week - Use one through three letters for the short day, four for the full (wide) name, five for the narrow name, or six for the short name.
    4 Tuesday
    5 T
    6 Tu
    a 1 AM AM or PM
    h 1..2 11 Hour [1-12]. When used in skeleton data or in a skeleton passed in an API for flexible data pattern generation, it should match the 12-hour-cycle format preferred by the locale (h or K); it should not match a 24-hour-cycle format (H or k). Use hh for zero padding.
    H 1..2 13 Hour [0-23]. When used in skeleton data or in a skeleton passed in an API for flexible data pattern generation, it should match the 24-hour-cycle format preferred by the locale (H or k); it should not match a 12-hour-cycle format (h or K). Use HH for zero padding.
    m 1..2 59 Minute. Use "m" to show the minimum number of digits, or "mm" to always show two digits (zero-padding if necessary, e.g. "08")..
    s 1..2 12 Second. Use "s" to show the minimum number of digits, or "ss" to always show two digits (zero-padding if necessary, e.g. "08").
    z 1..3 PDT Time zone. The short specific non-location format. Where that is unavailable, falls back to the short localized GMT format ("O").
    4 Pacific Daylight Time The long specific non-location format. Where that is unavailable, falls back to the long localized GMT format ("OOOO").
    v 1 PT Time zone. The short generic non-location format. Where that is unavailable, falls back to the generic location format ("VVVV"), then the short localized GMT format as the final fallback.
    4 Pacific Time The long generic non-location format. Where that is unavailable, falls back to generic location format ("VVVV").

    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
     
    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 UCharacter.isDigit(int), 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

    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.
    Author:
    Mark Davis, Chen-Lieh Huang, Alan Liu
    See Also:
    Calendar, GregorianCalendar, TimeZone, DateFormat, DateFormatSymbols, DecimalFormat, TimeZoneFormat, Serialized Form
    Status:
    Stable ICU 2.0.
    • Constructor Detail

      • SimpleDateFormat

        public SimpleDateFormat()
        Constructs a SimpleDateFormat using the default pattern for the default FORMAT locale. Note: Not all locales support SimpleDateFormat; for full generality, use the factory methods in the DateFormat class.
        See Also:
        DateFormat, ULocale.Category.FORMAT
        Status:
        Stable ICU 2.0.
      • SimpleDateFormat

        public SimpleDateFormat​(String pattern)
        Constructs a SimpleDateFormat using the given pattern in the default FORMAT locale. Note: Not all locales support SimpleDateFormat; for full generality, use the factory methods in the DateFormat class.
        See Also:
        ULocale.Category.FORMAT
        Status:
        Stable ICU 2.0.
      • SimpleDateFormat

        public SimpleDateFormat​(String pattern,
                                Locale loc)
        Constructs a SimpleDateFormat using the given pattern and locale. Note: Not all locales support SimpleDateFormat; for full generality, use the factory methods in the DateFormat class.
        Status:
        Stable ICU 2.0.
      • SimpleDateFormat

        public SimpleDateFormat​(String pattern,
                                ULocale loc)
        Constructs a SimpleDateFormat using the given pattern and locale. Note: Not all locales support SimpleDateFormat; for full generality, use the factory methods in the DateFormat class.
        Status:
        Stable ICU 3.2.
      • SimpleDateFormat

        public SimpleDateFormat​(String pattern,
                                String override,
                                ULocale loc)
        Constructs a SimpleDateFormat using the given pattern , override and locale.
        Parameters:
        pattern - The pattern to be used
        override - The override string. A numbering system override string can take one of the following forms: 1). If just a numbering system name is specified, it applies to all numeric fields in the date format pattern. 2). To specify an alternate numbering system on a field by field basis, use the field letters from the pattern followed by an = sign, followed by the numbering system name. For example, to specify that just the year be formatted using Hebrew digits, use the override "y=hebr". Multiple overrides can be specified in a single string by separating them with a semi-colon. For example, the override string "m=thai;y=deva" would format using Thai digits for the month and Devanagari digits for the year.
        loc - The locale to be used
        Status:
        Stable ICU 4.2.
      • SimpleDateFormat

        public SimpleDateFormat​(String pattern,
                                DateFormatSymbols formatData)
        Constructs a SimpleDateFormat using the given pattern and locale-specific symbol data. Warning: uses default FORMAT locale for digits!
        Status:
        Stable ICU 2.0.
      • SimpleDateFormat

        @Deprecated
        public SimpleDateFormat​(String pattern,
                                DateFormatSymbols formatData,
                                ULocale loc)
        Deprecated.
        This API is ICU internal only.
        Status:
        Internal. This API is ICU internal only.
    • Method Detail

      • getInstance

        @Deprecated
        public static SimpleDateFormat getInstance​(Calendar.FormatConfiguration formatConfig)
        Deprecated.
        This API is ICU internal only.
        Creates an instance of SimpleDateFormat for the given format configuration
        Parameters:
        formatConfig - the format configuration
        Returns:
        A SimpleDateFormat instance
        Status:
        Internal. This API is ICU internal only.
      • 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 range startDate to startDate + 100 years.
        Status:
        Stable ICU 2.0.
      • 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
        Status:
        Stable ICU 2.0.
      • setContext

        public void setContext​(DisplayContext context)
        [icu] Set a particular DisplayContext value in the formatter, such as CAPITALIZATION_FOR_STANDALONE. Note: For getContext, see DateFormat.
        Overrides:
        setContext in class DateFormat
        Parameters:
        context - The DisplayContext value to set.
        Status:
        Stable ICU 53.
      • format

        public StringBuffer format​(Calendar cal,
                                   StringBuffer toAppendTo,
                                   FieldPosition pos)
        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

        Specified by:
        format in class DateFormat
        Parameters:
        cal - the calendar whose date-time value is 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.
        See Also:
        DateFormat
        Status:
        Stable ICU 2.0.
      • patternCharToDateFormatField

        protected DateFormat.Field patternCharToDateFormatField​(char ch)
        Returns a DateFormat.Field constant associated with the specified format pattern character.
        Parameters:
        ch - The pattern character
        Returns:
        DateFormat.Field associated with the pattern character
        Status:
        Stable ICU 3.8.
      • subFormat

        protected String subFormat​(char ch,
                                   int count,
                                   int beginOffset,
                                   FieldPosition pos,
                                   DateFormatSymbols fmtData,
                                   Calendar cal)
                            throws IllegalArgumentException
        Formats a single field, given its pattern character. Subclasses may override this method in order to modify or add formatting capabilities.
        Parameters:
        ch - the pattern character
        count - the number of times ch is repeated in the pattern
        beginOffset - the offset of the output string at the start of this field; used to set pos when appropriate
        pos - receives the position of a field, when appropriate
        fmtData - the symbols for this formatter
        Throws:
        IllegalArgumentException
        Status:
        Stable ICU 2.0.
      • subFormat

        @Deprecated
        protected String subFormat​(char ch,
                                   int count,
                                   int beginOffset,
                                   int fieldNum,
                                   DisplayContext capitalizationContext,
                                   FieldPosition pos,
                                   char patternCharToOutput,
                                   Calendar cal)
        Deprecated.
        This API is ICU internal only.
        Formats a single field. This is the version called internally; it adds fieldNum and capitalizationContext parameters.
        Status:
        Internal. This API is ICU internal only.
      • subFormat

        @Deprecated
        protected void subFormat​(StringBuffer buf,
                                 char ch,
                                 int count,
                                 int beginOffset,
                                 int fieldNum,
                                 DisplayContext capitalizationContext,
                                 FieldPosition pos,
                                 char patternCharToOutput,
                                 Calendar cal)
        Deprecated.
        This API is ICU internal only.
        Formats a single field; useFastFormat variant. Reuses a StringBuffer for results instead of creating a String on the heap for each call. NOTE We don't really need the beginOffset parameter, EXCEPT for the need to support the slow subFormat variant (above) which has to pass it in to us.
        Status:
        Internal. This API is ICU internal only.
      • zeroPaddingNumber

        @Deprecated
        protected void zeroPaddingNumber​(NumberFormat nf,
                                         StringBuffer buf,
                                         int value,
                                         int minDigits,
                                         int maxDigits)
        Deprecated.
        This API is ICU internal only.
        Internal high-speed method. Reuses a StringBuffer for results instead of creating a String on the heap for each call.
        Status:
        Internal. This API is ICU internal only.
      • zeroPaddingNumber

        protected String zeroPaddingNumber​(long value,
                                           int minDigits,
                                           int maxDigits)
        Formats a number with the specified minimum and maximum number of digits.
        Status:
        Stable ICU 2.0.
      • parse

        public void parse​(String text,
                          Calendar cal,
                          ParsePosition parsePos)
        Overrides DateFormat
        Specified by:
        parse in class DateFormat
        Parameters:
        text - The date/time string to be parsed
        cal - The calendar set on input to the date and time to be used for missing values in the date/time string being parsed, and set on output to the parsed date/time. In general, this should be initialized before calling this method - either cleared or set to the current date, depending on desired behavior. If this parse fails, the calendar may still have been modified. When the calendar type is different from the internal calendar held by this DateFormat instance, calendar field values will be parsed based on the internal calendar initialized with the time and the time zone taken from this calendar, then the parse result (time in milliseconds and time zone) will be set back to this calendar.
        parsePos - On input, the position at which to start parsing; on output, the position at which parsing terminated, or the start position if the parse failed.
        See Also:
        DateFormat
        Status:
        Stable ICU 2.0.
      • matchString

        protected int matchString​(String text,
                                  int start,
                                  int field,
                                  String[] data,
                                  Calendar cal)
        Attempt to match the text at a given position against an array of strings. Since multiple strings in the array may match (for example, if the array contains "a", "ab", and "abc", all will match the input string "abcd") the longest match is returned. As a side effect, the given field of cal is set to the index of the best match, if there is one.
        Parameters:
        text - the time text being parsed.
        start - where to start parsing.
        field - the date field being parsed.
        data - the string array to parsed.
        cal -
        Returns:
        the new start position if matching succeeded; a negative number indicating matching failure, otherwise. As a side effect, sets the cal field field to the index of the best match, if matching succeeded.
        Status:
        Stable ICU 2.0.
      • matchQuarterString

        protected int matchQuarterString​(String text,
                                         int start,
                                         int field,
                                         String[] data,
                                         Calendar cal)
        Attempt to match the text at a given position against an array of quarter strings. Since multiple strings in the array may match (for example, if the array contains "a", "ab", and "abc", all will match the input string "abcd") the longest match is returned. As a side effect, the given field of cal is set to the index of the best match, if there is one.
        Parameters:
        text - the time text being parsed.
        start - where to start parsing.
        field - the date field being parsed.
        data - the string array to parsed.
        Returns:
        the new start position if matching succeeded; a negative number indicating matching failure, otherwise. As a side effect, sets the cal field field to the index of the best match, if matching succeeded.
        Status:
        Stable ICU 2.0.
      • subParse

        protected int subParse​(String text,
                               int start,
                               char ch,
                               int count,
                               boolean obeyCount,
                               boolean allowNegative,
                               boolean[] ambiguousYear,
                               Calendar cal)
        Protected method that converts one field of the input string into a numeric field value in cal. Returns -start (for ParsePosition) if failed. Subclasses may override this method to modify or add parsing capabilities.
        Parameters:
        text - the time text to be parsed.
        start - where to start parsing.
        ch - the pattern character for the date field text to be parsed.
        count - the count of a pattern character.
        obeyCount - if true, then the next field directly abuts this one, and we should use the count to know when to stop parsing.
        ambiguousYear - return parameter; upon return, if ambiguousYear[0] is true, then a two-digit year was parsed and may need to be readjusted.
        cal -
        Returns:
        the new start position if matching succeeded; a negative number indicating matching failure, otherwise. As a side effect, set the appropriate field of cal with the parsed value.
        Status:
        Stable ICU 2.0.
      • toPattern

        public String toPattern()
        Return a pattern string describing this date format.
        Status:
        Stable ICU 2.0.
      • toLocalizedPattern

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

        Note: This implementation depends on DateFormatSymbols.getLocalPatternChars() to get localized format pattern characters. ICU does not include localized pattern character data, therefore, unless user sets localized pattern characters manually, this method returns the same result as toPattern().

        Status:
        Stable ICU 2.0.
      • applyPattern

        public void applyPattern​(String pat)
        Apply the given unlocalized pattern string to this date format.
        Status:
        Stable ICU 2.0.
      • applyLocalizedPattern

        public void applyLocalizedPattern​(String pat)
        Apply the given localized pattern string to this date format.
        Status:
        Stable ICU 2.0.
      • getDateFormatSymbols

        public DateFormatSymbols getDateFormatSymbols()
        Gets the date/time formatting data.
        Returns:
        a copy of the date-time formatting data associated with this date-time formatter.
        Status:
        Stable ICU 2.0.
      • setDateFormatSymbols

        public void setDateFormatSymbols​(DateFormatSymbols newFormatSymbols)
        Allows you to set the date/time formatting data.
        Parameters:
        newFormatSymbols - the new symbols
        Status:
        Stable ICU 2.0.
      • getSymbols

        protected DateFormatSymbols getSymbols()
        Method for subclasses to access the DateFormatSymbols.
        Status:
        Stable ICU 2.0.
      • getTimeZoneFormat

        public TimeZoneFormat getTimeZoneFormat()
        [icu] Gets the time zone formatter which this date/time formatter uses to format and parse a time zone.
        Returns:
        the time zone formatter which this date/time formatter uses.
        Status:
        Stable ICU 49.
      • setTimeZoneFormat

        public void setTimeZoneFormat​(TimeZoneFormat tzfmt)
        [icu] Allows you to set the time zone formatter.
        Parameters:
        tzfmt - the new time zone formatter
        Status:
        Stable ICU 49.
      • hashCode

        public int hashCode()
        Override hashCode. Generates the hash code for the SimpleDateFormat object
        Overrides:
        hashCode in class DateFormat
        Status:
        Stable ICU 2.0.
      • equals

        public boolean equals​(Object obj)
        Override equals.
        Overrides:
        equals in class DateFormat
        Status:
        Stable ICU 2.0.
      • formatToCharacterIterator

        public AttributedCharacterIterator formatToCharacterIterator​(Object obj)
        Format the object to an attributed string, and return the corresponding iterator Overrides superclass method.
        Overrides:
        formatToCharacterIterator in class Format
        Parameters:
        obj - The object to format
        Returns:
        AttributedCharacterIterator describing the formatted value.
        Status:
        Stable ICU 3.8.
      • intervalFormatByAlgorithm

        @Deprecated
        public final StringBuffer intervalFormatByAlgorithm​(Calendar fromCalendar,
                                                            Calendar toCalendar,
                                                            StringBuffer appendTo,
                                                            FieldPosition pos)
                                                     throws IllegalArgumentException
        Deprecated.
        This API is ICU internal only.
        Format date interval by algorithm. It is supposed to be used only by CLDR survey tool.
        Parameters:
        fromCalendar - calendar set to the from date in date interval to be formatted into date interval string
        toCalendar - calendar set to the to date in date interval to be formatted into date interval string
        appendTo - Output parameter to receive result. Result is appended to existing contents.
        pos - On input: an alignment field, if desired. On output: the offsets of the alignment field.
        Returns:
        Reference to 'appendTo' parameter.
        Throws:
        IllegalArgumentException - when there is non-recognized pattern letter
        Status:
        Internal. This API is ICU internal only.
      • setNumberFormat

        public void setNumberFormat​(String fields,
                                    NumberFormat overrideNF)
        allow the user to set the NumberFormat for several fields It can be a single field like: "y"(year) or "M"(month) It can be several field combined together: "yMd"(year, month and date) Note: 1 symbol field is enough for multiple symbol fields (so "y" will override "yy", "yyy") If the field is not numeric, then override has no effect (like "MMM" will use abbreviation, not numerical field)
        Parameters:
        fields - the fields to override
        overrideNF - the NumbeferFormat used
        Throws:
        IllegalArgumentException - when the fields contain invalid field
        Status:
        Stable ICU 54.
      • getNumberFormat

        public NumberFormat getNumberFormat​(char field)
        give the NumberFormat used for the field like 'y'(year) and 'M'(year)
        Parameters:
        field - the field the user wants
        Returns:
        override NumberFormat used for the field
        Status:
        Stable ICU 54.