org.apache.commons.lang3.time

## Class FastDateFormat

- java.lang.Object
- - java.text.Format
  - - org.apache.commons.lang3.time.FastDateFormat

- All Implemented Interfaces:
    Serializable, Cloneable, DateParser, DatePrinter

      public class FastDateFormat
      extends Format
      implements DateParser, DatePrinter

  FastDateFormat is a fast and thread-safe version of `SimpleDateFormat`.

  This class can be used as a direct replacement to `SimpleDateFormat` in most formatting and parsing situations. This class is especially useful in multi-threaded server environments. `SimpleDateFormat` is not thread-safe in any JDK version, nor will it be as Sun have closed the bug/RFE.

  All patterns are compatible with SimpleDateFormat (except time zones and some year patterns - see below).

  Since 3.2, FastDateFormat supports parsing as well as printing.

  Java 1.4 introduced a new pattern letter, `'Z'`, to represent time zones in RFC822 format (eg. `+0800` or `-1100`). This pattern letter can be used here (on all JDK versions).

  In addition, the pattern `'ZZ'` has been made to represent ISO8601 full format time zones (eg. `+08:00` or `-11:00`). This introduces a minor incompatibility with Java 1.4, but at a gain of useful functionality.

  Javadoc cites for the year pattern: For formatting, if the number of pattern letters is 2, the year is truncated to 2 digits; otherwise it is interpreted as a number. Starting with Java 1.7 a pattern of 'Y' or 'YYY' will be formatted as '2003', while it was '03' in former Java versions. FastDateFormat implements the behavior of Java 7.

  Since:
    2.0
  Version:
    $Id: FastDateFormat.java 1572877 2014-02-28 08:42:25Z britter $
  See Also:
    Serialized Form

- - ### Nested Class Summary

    - ### Nested classes/interfaces inherited from class java.text.Format

      `Format.Field`

  - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `static int` | `FULL` FULL locale dependent date or time style.
    `static int` | `LONG` LONG locale dependent date or time style.
    `static int` | `MEDIUM` MEDIUM locale dependent date or time style.
    `static int` | `SHORT` SHORT locale dependent date or time style.

  - ### Constructor Summary

    Constructors
    Modifier | Constructor and Description
    --- | ---
    `protected` | `FastDateFormat(String pattern, TimeZone timeZone, Locale locale)` Constructs a new FastDateFormat.
    `protected` | `FastDateFormat(String pattern, TimeZone timeZone, Locale locale, Date centuryStart)` Constructs a new FastDateFormat.

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `protected StringBuffer` | `applyRules(Calendar calendar, StringBuffer buf)` Performs the formatting by applying the rules to the specified calendar.
    `boolean` | `equals(Object obj)` Compares two objects for equality.
    `String` | `format(Calendar calendar)` Formats a `Calendar` object.
    `StringBuffer` | `format(Calendar calendar, StringBuffer buf)` Formats a `Calendar` object into the supplied `StringBuffer`.
    `String` | `format(Date date)` Formats a `Date` object using a `GregorianCalendar`.
    `StringBuffer` | `format(Date date, StringBuffer buf)` Formats a `Date` object into the supplied `StringBuffer` using a `GregorianCalendar`.
    `String` | `format(long millis)` Formats a millisecond `long` value.
    `StringBuffer` | `format(long millis, StringBuffer buf)` Formats a millisecond `long` value into the supplied `StringBuffer`.
    `StringBuffer` | `format(Object obj, StringBuffer toAppendTo, FieldPosition pos)` Formats a `Date`, `Calendar` or `Long` (milliseconds) object.
    `static FastDateFormat` | `getDateInstance(int style)` Gets a date formatter instance using the specified style in the default time zone and locale.
    `static FastDateFormat` | `getDateInstance(int style, Locale locale)` Gets a date formatter instance using the specified style and locale in the default time zone.
    `static FastDateFormat` | `getDateInstance(int style, TimeZone timeZone)` Gets a date formatter instance using the specified style and time zone in the default locale.
    `static FastDateFormat` | `getDateInstance(int style, TimeZone timeZone, Locale locale)` Gets a date formatter instance using the specified style, time zone and locale.
    `static FastDateFormat` | `getDateTimeInstance(int dateStyle, int timeStyle)` Gets a date/time formatter instance using the specified style in the default time zone and locale.
    `static FastDateFormat` | `getDateTimeInstance(int dateStyle, int timeStyle, Locale locale)` Gets a date/time formatter instance using the specified style and locale in the default time zone.
    `static FastDateFormat` | `getDateTimeInstance(int dateStyle, int timeStyle, TimeZone timeZone)` Gets a date/time formatter instance using the specified style and time zone in the default locale.
    `static FastDateFormat` | `getDateTimeInstance(int dateStyle, int timeStyle, TimeZone timeZone, Locale locale)` Gets a date/time formatter instance using the specified style, time zone and locale.
    `static FastDateFormat` | `getInstance()` Gets a formatter instance using the default pattern in the default locale.
    `static FastDateFormat` | `getInstance(String pattern)` Gets a formatter instance using the specified pattern in the default locale.
    `static FastDateFormat` | `getInstance(String pattern, Locale locale)` Gets a formatter instance using the specified pattern and locale.
    `static FastDateFormat` | `getInstance(String pattern, TimeZone timeZone)` Gets a formatter instance using the specified pattern and time zone.
    `static FastDateFormat` | `getInstance(String pattern, TimeZone timeZone, Locale locale)` Gets a formatter instance using the specified pattern, time zone and locale.
    `Locale` | `getLocale()` Gets the locale used by this formatter.
    `int` | `getMaxLengthEstimate()` Gets an estimate for the maximum string length that the formatter will produce.
    `String` | `getPattern()` Gets the pattern used by this formatter.
    `static FastDateFormat` | `getTimeInstance(int style)` Gets a time formatter instance using the specified style in the default time zone and locale.
    `static FastDateFormat` | `getTimeInstance(int style, Locale locale)` Gets a time formatter instance using the specified style and locale in the default time zone.
    `static FastDateFormat` | `getTimeInstance(int style, TimeZone timeZone)` Gets a time formatter instance using the specified style and time zone in the default locale.
    `static FastDateFormat` | `getTimeInstance(int style, TimeZone timeZone, Locale locale)` Gets a time formatter instance using the specified style, time zone and locale.
    `TimeZone` | `getTimeZone()` Gets the time zone used by this formatter.
    `int` | `hashCode()` Returns a hashcode compatible with equals.
    `Date` | `parse(String source)` Equivalent to DateFormat.parse(String).
    `Date` | `parse(String source, ParsePosition pos)` Equivalent to DateFormat.parse(String, ParsePosition).
    `Object` | `parseObject(String source, ParsePosition pos)` Parse a date/time string according to the given parse position.
    `String` | `toString()` Gets a debugging string version of this formatter.

    - ### Methods inherited from class java.text.Format

      `clone, format, formatToCharacterIterator, parseObject`

    - ### Methods inherited from class java.lang.Object

      `finalize, getClass, notify, notifyAll, wait, wait, wait`

    - ### Methods inherited from interface org.apache.commons.lang3.time.DateParser

      `parseObject`

- - ### Field Detail

    - #### FULL

          public static final int FULL

      FULL locale dependent date or time style.
      See Also:
        Constant Field Values

    - #### LONG

          public static final int LONG

      LONG locale dependent date or time style.
      See Also:
        Constant Field Values

    - #### MEDIUM

          public static final int MEDIUM

      MEDIUM locale dependent date or time style.
      See Also:
        Constant Field Values

    - #### SHORT

          public static final int SHORT

      SHORT locale dependent date or time style.
      See Also:
        Constant Field Values

  - ### Constructor Detail

    - #### FastDateFormat

          protected FastDateFormat(String pattern,
                        TimeZone timeZone,
                        Locale locale)

      Constructs a new FastDateFormat.

      Parameters:
        `pattern` - `SimpleDateFormat` compatible pattern
        `timeZone` - non-null time zone to use
        `locale` - non-null locale to use
      Throws:
        `NullPointerException` - if pattern, timeZone, or locale is null.

    - #### FastDateFormat

          protected FastDateFormat(String pattern,
                        TimeZone timeZone,
                        Locale locale,
                        Date centuryStart)

      Constructs a new FastDateFormat.

      Parameters:
        `pattern` - `SimpleDateFormat` compatible pattern
        `timeZone` - non-null time zone to use
        `locale` - non-null locale to use
        `centuryStart` - The start of the 100 year period to use as the "default century" for 2 digit year parsing. If centuryStart is null, defaults to now - 80 years
      Throws:
        `NullPointerException` - if pattern, timeZone, or locale is null.

  - ### Method Detail

    - #### getInstance

          public static FastDateFormat getInstance()

      Gets a formatter instance using the default pattern in the default locale.

      Returns:
        a date/time formatter

    - #### getInstance

          public static FastDateFormat getInstance(String pattern)

      Gets a formatter instance using the specified pattern in the default locale.

      Parameters:
        `pattern` - `SimpleDateFormat` compatible pattern
      Returns:
        a pattern based date/time formatter
      Throws:
        `IllegalArgumentException` - if pattern is invalid

    - #### getInstance

          public static FastDateFormat getInstance(String pattern,
                                   TimeZone timeZone)

      Gets a formatter instance using the specified pattern and time zone.

      Parameters:
        `pattern` - `SimpleDateFormat` compatible pattern
        `timeZone` - optional time zone, overrides time zone of formatted date
      Returns:
        a pattern based date/time formatter
      Throws:
        `IllegalArgumentException` - if pattern is invalid

    - #### getInstance

          public static FastDateFormat getInstance(String pattern,
                                   Locale locale)

      Gets a formatter instance using the specified pattern and locale.

      Parameters:
        `pattern` - `SimpleDateFormat` compatible pattern
        `locale` - optional locale, overrides system locale
      Returns:
        a pattern based date/time formatter
      Throws:
        `IllegalArgumentException` - if pattern is invalid

    - #### getInstance

          public static FastDateFormat getInstance(String pattern,
                                   TimeZone timeZone,
                                   Locale locale)

      Gets a formatter instance using the specified pattern, time zone and locale.

      Parameters:
        `pattern` - `SimpleDateFormat` compatible pattern
        `timeZone` - optional time zone, overrides time zone of formatted date
        `locale` - optional locale, overrides system locale
      Returns:
        a pattern based date/time formatter
      Throws:
        `IllegalArgumentException` - if pattern is invalid or `null`

    - #### getDateInstance

          public static FastDateFormat getDateInstance(int style)

      Gets a date formatter instance using the specified style in the default time zone and locale.

      Parameters:
        `style` - date style: FULL, LONG, MEDIUM, or SHORT
      Returns:
        a localized standard date formatter
      Throws:
        `IllegalArgumentException` - if the Locale has no date pattern defined
      Since:
        2.1

    - #### getDateInstance

          public static FastDateFormat getDateInstance(int style,
                                       Locale locale)

      Gets a date formatter instance using the specified style and locale in the default time zone.

      Parameters:
        `style` - date style: FULL, LONG, MEDIUM, or SHORT
        `locale` - optional locale, overrides system locale
      Returns:
        a localized standard date formatter
      Throws:
        `IllegalArgumentException` - if the Locale has no date pattern defined
      Since:
        2.1

    - #### getDateInstance

          public static FastDateFormat getDateInstance(int style,
                                       TimeZone timeZone)

      Gets a date formatter instance using the specified style and time zone in the default locale.

      Parameters:
        `style` - date style: FULL, LONG, MEDIUM, or SHORT
        `timeZone` - optional time zone, overrides time zone of formatted date
      Returns:
        a localized standard date formatter
      Throws:
        `IllegalArgumentException` - if the Locale has no date pattern defined
      Since:
        2.1

    - #### getDateInstance

          public static FastDateFormat getDateInstance(int style,
                                       TimeZone timeZone,
                                       Locale locale)

      Gets a date formatter instance using the specified style, time zone and locale.

      Parameters:
        `style` - date style: FULL, LONG, MEDIUM, or SHORT
        `timeZone` - optional time zone, overrides time zone of formatted date
        `locale` - optional locale, overrides system locale
      Returns:
        a localized standard date formatter
      Throws:
        `IllegalArgumentException` - if the Locale has no date pattern defined

    - #### getTimeInstance

          public static FastDateFormat getTimeInstance(int style)

      Gets a time formatter instance using the specified style in the default time zone and locale.

      Parameters:
        `style` - time style: FULL, LONG, MEDIUM, or SHORT
      Returns:
        a localized standard time formatter
      Throws:
        `IllegalArgumentException` - if the Locale has no time pattern defined
      Since:
        2.1

    - #### getTimeInstance

          public static FastDateFormat getTimeInstance(int style,
                                       Locale locale)

      Gets a time formatter instance using the specified style and locale in the default time zone.

      Parameters:
        `style` - time style: FULL, LONG, MEDIUM, or SHORT
        `locale` - optional locale, overrides system locale
      Returns:
        a localized standard time formatter
      Throws:
        `IllegalArgumentException` - if the Locale has no time pattern defined
      Since:
        2.1

    - #### getTimeInstance

          public static FastDateFormat getTimeInstance(int style,
                                       TimeZone timeZone)

      Gets a time formatter instance using the specified style and time zone in the default locale.

      Parameters:
        `style` - time style: FULL, LONG, MEDIUM, or SHORT
        `timeZone` - optional time zone, overrides time zone of formatted time
      Returns:
        a localized standard time formatter
      Throws:
        `IllegalArgumentException` - if the Locale has no time pattern defined
      Since:
        2.1

    - #### getTimeInstance

          public static FastDateFormat getTimeInstance(int style,
                                       TimeZone timeZone,
                                       Locale locale)

      Gets a time formatter instance using the specified style, time zone and locale.

      Parameters:
        `style` - time style: FULL, LONG, MEDIUM, or SHORT
        `timeZone` - optional time zone, overrides time zone of formatted time
        `locale` - optional locale, overrides system locale
      Returns:
        a localized standard time formatter
      Throws:
        `IllegalArgumentException` - if the Locale has no time pattern defined

    - #### getDateTimeInstance

          public static FastDateFormat getDateTimeInstance(int dateStyle,
                                           int timeStyle)

      Gets a date/time formatter instance using the specified style in the default time zone and locale.

      Parameters:
        `dateStyle` - date style: FULL, LONG, MEDIUM, or SHORT
        `timeStyle` - time style: FULL, LONG, MEDIUM, or SHORT
      Returns:
        a localized standard date/time formatter
      Throws:
        `IllegalArgumentException` - if the Locale has no date/time pattern defined
      Since:
        2.1

    - #### getDateTimeInstance

          public static FastDateFormat getDateTimeInstance(int dateStyle,
                                           int timeStyle,
                                           Locale locale)

      Gets a date/time formatter instance using the specified style and locale in the default time zone.

      Parameters:
        `dateStyle` - date style: FULL, LONG, MEDIUM, or SHORT
        `timeStyle` - time style: FULL, LONG, MEDIUM, or SHORT
        `locale` - optional locale, overrides system locale
      Returns:
        a localized standard date/time formatter
      Throws:
        `IllegalArgumentException` - if the Locale has no date/time pattern defined
      Since:
        2.1

    - #### getDateTimeInstance

          public static FastDateFormat getDateTimeInstance(int dateStyle,
                                           int timeStyle,
                                           TimeZone timeZone)

      Gets a date/time formatter instance using the specified style and time zone in the default locale.

      Parameters:
        `dateStyle` - date style: FULL, LONG, MEDIUM, or SHORT
        `timeStyle` - time style: FULL, LONG, MEDIUM, or SHORT
        `timeZone` - optional time zone, overrides time zone of formatted date
      Returns:
        a localized standard date/time formatter
      Throws:
        `IllegalArgumentException` - if the Locale has no date/time pattern defined
      Since:
        2.1

    - #### getDateTimeInstance

          public static FastDateFormat getDateTimeInstance(int dateStyle,
                                           int timeStyle,
                                           TimeZone timeZone,
                                           Locale locale)

      Gets a date/time formatter instance using the specified style, time zone and locale.

      Parameters:
        `dateStyle` - date style: FULL, LONG, MEDIUM, or SHORT
        `timeStyle` - time style: FULL, LONG, MEDIUM, or SHORT
        `timeZone` - optional time zone, overrides time zone of formatted date
        `locale` - optional locale, overrides system locale
      Returns:
        a localized standard date/time formatter
      Throws:
        `IllegalArgumentException` - if the Locale has no date/time pattern defined

    - #### format

          public StringBuffer format(Object obj,
                            StringBuffer toAppendTo,
                            FieldPosition pos)

      Formats a `Date`, `Calendar` or `Long` (milliseconds) object.

      Specified by:
        `format` in interface `DatePrinter`
      Specified by:
        `format` in class `Format`
      Parameters:
        `obj` - the object to format
        `toAppendTo` - the buffer to append to
        `pos` - the position - ignored
      Returns:
        the buffer passed in

    - #### format

          public String format(long millis)

      Formats a millisecond `long` value.

      Specified by:
        `format` in interface `DatePrinter`
      Parameters:
        `millis` - the millisecond value to format
      Returns:
        the formatted string
      Since:
        2.1

    - #### format

          public String format(Date date)

      Formats a `Date` object using a `GregorianCalendar`.

      Specified by:
        `format` in interface `DatePrinter`
      Parameters:
        `date` - the date to format
      Returns:
        the formatted string

    - #### format

          public String format(Calendar calendar)

      Formats a `Calendar` object.

      Specified by:
        `format` in interface `DatePrinter`
      Parameters:
        `calendar` - the calendar to format
      Returns:
        the formatted string

    - #### format

          public StringBuffer format(long millis,
                            StringBuffer buf)

      Formats a millisecond `long` value into the supplied `StringBuffer`.

      Specified by:
        `format` in interface `DatePrinter`
      Parameters:
        `millis` - the millisecond value to format
        `buf` - the buffer to format into
      Returns:
        the specified string buffer
      Since:
        2.1

    - #### format

          public StringBuffer format(Date date,
                            StringBuffer buf)

      Formats a `Date` object into the supplied `StringBuffer` using a `GregorianCalendar`.

      Specified by:
        `format` in interface `DatePrinter`
      Parameters:
        `date` - the date to format
        `buf` - the buffer to format into
      Returns:
        the specified string buffer

    - #### format

          public StringBuffer format(Calendar calendar,
                            StringBuffer buf)

      Formats a `Calendar` object into the supplied `StringBuffer`.

      Specified by:
        `format` in interface `DatePrinter`
      Parameters:
        `calendar` - the calendar to format
        `buf` - the buffer to format into
      Returns:
        the specified string buffer

    - #### parse

          public Date parse(String source)
                     throws ParseException

      Description copied from interface: `DateParser`
      Equivalent to DateFormat.parse(String). See `DateFormat.parse(String)` for more information.
      Specified by:
        `parse` in interface `DateParser`
      Parameters:
        `source` - A `String` whose beginning should be parsed.
      Returns:
        A `Date` parsed from the string
      Throws:
        `ParseException` - if the beginning of the specified string cannot be parsed.

    - #### parse

          public Date parse(String source,
                   ParsePosition pos)

      Description copied from interface: `DateParser`
      Equivalent to DateFormat.parse(String, ParsePosition). See `DateFormat.parse(String, ParsePosition)` for more information.
      Specified by:
        `parse` in interface `DateParser`
      Parameters:
        `source` - A `String`, part of which should be parsed.
        `pos` - A `ParsePosition` object with index and error index information as described above.
      Returns:
        A `Date` parsed from the string. In case of error, returns null.

    - #### parseObject

          public Object parseObject(String source,
                           ParsePosition pos)

      Description copied from interface: `DateParser`
      Parse a date/time string according to the given parse position.
      Specified by:
        `parseObject` in interface `DateParser`
      Specified by:
        `parseObject` in class `Format`
      Parameters:
        `source` - A `String` whose beginning should be parsed.
        `pos` - the parse position
      Returns:
        a `java.util.Date` object
      See Also:
        `DateFormat.parseObject(String, ParsePosition)`

    - #### getPattern

          public String getPattern()

      Gets the pattern used by this formatter.

      Specified by:
        `getPattern` in interface `DateParser`
      Specified by:
        `getPattern` in interface `DatePrinter`
      Returns:
        the pattern, `SimpleDateFormat` compatible

    - #### getTimeZone

          public TimeZone getTimeZone()

      Gets the time zone used by this formatter.

      This zone is always used for `Date` formatting.

      Specified by:
        `getTimeZone` in interface `DateParser`
      Specified by:
        `getTimeZone` in interface `DatePrinter`
      Returns:
        the time zone

    - #### getLocale

          public Locale getLocale()

      Gets the locale used by this formatter.

      Specified by:
        `getLocale` in interface `DateParser`
      Specified by:
        `getLocale` in interface `DatePrinter`
      Returns:
        the locale

    - #### getMaxLengthEstimate

          public int getMaxLengthEstimate()

      Gets an estimate for the maximum string length that the formatter will produce.

      The actual formatted length will almost always be less than or equal to this amount.

      Returns:
        the maximum formatted length

    - #### equals

          public boolean equals(Object obj)

      Compares two objects for equality.

      Overrides:
        `equals` in class `Object`
      Parameters:
        `obj` - the object to compare to
      Returns:
        `true` if equal

    - #### hashCode

          public int hashCode()

      Returns a hashcode compatible with equals.

      Overrides:
        `hashCode` in class `Object`
      Returns:
        a hashcode compatible with equals

    - #### toString

          public String toString()

      Gets a debugging string version of this formatter.

      Overrides:
        `toString` in class `Object`
      Returns:
        a debugging string

    - #### applyRules

          protected StringBuffer applyRules(Calendar calendar,
                                StringBuffer buf)

      Performs the formatting by applying the rules to the specified calendar.

      Parameters:
        `calendar` - the calendar to format
        `buf` - the buffer to format into
      Returns:
        the specified string buffer

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