Package java.text

Class SimpleDateFormat

  • public class SimpleDateFormat
extends DateFormat
    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):

    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
    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'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 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 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.
      Otherwise system specific forms are applied. For both formatting and parsing, if the number of pattern letters is 4 or more, a calendar specific long form is used. Otherwise, a calendar specific short or abbreviated form is used.

    • Month: If the number of pattern letters is 3 or more, the month is interpreted as text; otherwise, it is interpreted as a number.

    Examples

    The following examples show how date and time patterns are interpreted.
    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.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.

    See Also:
    Java Tutorial, Calendar, DateFormat, DateFormatSymbols

    • Constructor Detail

      • SimpleDateFormat

        public SimpleDateFormat()
        Constructs a SimpleDateFormat using the default pattern and date format symbols. Note: This constructor may not support all locales. For full coverage, use the factory methods in the DateFormat class.

      • SimpleDateFormat

        public SimpleDateFormat​(String pattern)
        Constructs a SimpleDateFormat using the given pattern and the default date format symbols. For full coverage, use the factory methods in the DateFormat class.

        This is equivalent to calling.

        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

      • SimpleDateFormat

        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

    • Method Detail

      • format

        public String format​(Date date)
        Description copied from class: DateFormat
        Formats a Date into a date/time string.
        Specified by:
        format in class DateFormat
        Parameters:
        date - the time value to be formatted into a time string.
        Returns:
        the formatted time string.

      • toPattern

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

      • 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:
        getDateFormatSymbols()