FastDateFormat (Lang 2.6)
Date: 2019-09-02

org.apache.commons.lang.time

## Class FastDateFormat

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

- All Implemented Interfaces:
    java.io.Serializable, java.lang.Cloneable

      public class FastDateFormat
      extends java.text.Format

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

  This class can be used as a direct replacement to `SimpleDateFormat` in most formatting 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.

  Only formatting is supported, but all patterns are compatible with SimpleDateFormat (except time zones - see below).

  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.

  Since:
    2.0
  Version:
    $Id: FastDateFormat.java 1057072 2011-01-10 01:55:57Z niallp $
  See Also:
    Serialized Form

- - ### Nested Class Summary

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

      `java.text.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(java.lang.String pattern, java.util.TimeZone timeZone, java.util.Locale locale)` Constructs a new FastDateFormat.

  - ### Method Summary

    All Methods Static Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `protected java.lang.StringBuffer` | `applyRules(java.util.Calendar calendar, java.lang.StringBuffer buf)` Performs the formatting by applying the rules to the specified calendar.
    `boolean` | `equals(java.lang.Object obj)` Compares two objects for equality.
    `java.lang.String` | `format(java.util.Calendar calendar)` Formats a `Calendar` object.
    `java.lang.StringBuffer` | `format(java.util.Calendar calendar, java.lang.StringBuffer buf)` Formats a `Calendar` object into the supplied `StringBuffer`.
    `java.lang.String` | `format(java.util.Date date)` Formats a `Date` object.
    `java.lang.StringBuffer` | `format(java.util.Date date, java.lang.StringBuffer buf)` Formats a `Date` object into the supplied `StringBuffer`.
    `java.lang.String` | `format(long millis)` Formats a millisecond `long` value.
    `java.lang.StringBuffer` | `format(long millis, java.lang.StringBuffer buf)` Formats a milliseond `long` value into the supplied `StringBuffer`.
    `java.lang.StringBuffer` | `format(java.lang.Object obj, java.lang.StringBuffer toAppendTo, java.text.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, java.util.Locale locale)` Gets a date formatter instance using the specified style and locale in the default time zone.
    `static FastDateFormat` | `getDateInstance(int style, java.util.TimeZone timeZone)` Gets a date formatter instance using the specified style and time zone in the default locale.
    `static FastDateFormat` | `getDateInstance(int style, java.util.TimeZone timeZone, java.util.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, java.util.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, java.util.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, java.util.TimeZone timeZone, java.util.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(java.lang.String pattern)` Gets a formatter instance using the specified pattern in the default locale.
    `static FastDateFormat` | `getInstance(java.lang.String pattern, java.util.Locale locale)` Gets a formatter instance using the specified pattern and locale.
    `static FastDateFormat` | `getInstance(java.lang.String pattern, java.util.TimeZone timeZone)` Gets a formatter instance using the specified pattern and time zone.
    `static FastDateFormat` | `getInstance(java.lang.String pattern, java.util.TimeZone timeZone, java.util.Locale locale)` Gets a formatter instance using the specified pattern, time zone and locale.
    `java.util.Locale` | `getLocale()` Gets the locale used by this formatter.
    `int` | `getMaxLengthEstimate()` Gets an estimate for the maximum string length that the formatter will produce.
    `java.lang.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, java.util.Locale locale)` Gets a time formatter instance using the specified style and locale in the default time zone.
    `static FastDateFormat` | `getTimeInstance(int style, java.util.TimeZone timeZone)` Gets a time formatter instance using the specified style and time zone in the default locale.
    `static FastDateFormat` | `getTimeInstance(int style, java.util.TimeZone timeZone, java.util.Locale locale)` Gets a time formatter instance using the specified style, time zone and locale.
    `java.util.TimeZone` | `getTimeZone()` Gets the time zone used by this formatter.
    `boolean` | `getTimeZoneOverridesCalendar()` Returns `true` if the time zone of the calendar overrides the time zone of the formatter.
    `int` | `hashCode()` Returns a hashcode compatible with equals.
    `protected void` | `init()` Initializes the instance for first use.
    `java.lang.Object` | `parseObject(java.lang.String source, java.text.ParsePosition pos)` Parsing is not supported.
    `protected java.util.List` | `parsePattern()` Returns a list of Rules given a pattern.
    `protected java.lang.String` | `parseToken(java.lang.String pattern, int[] indexRef)` Performs the parsing of tokens.
    `protected org.apache.commons.lang.time.FastDateFormat.NumberRule` | `selectNumberRule(int field, int padding)` Gets an appropriate rule for the padding required.
    `java.lang.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`

- - ### 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(java.lang.String pattern,
                                   java.util.TimeZone timeZone,
                                   java.util.Locale locale)

      Constructs a new FastDateFormat.

      Parameters:
        `pattern` - `SimpleDateFormat` compatible pattern
        `timeZone` - time zone to use, `null` means use default for `Date` and value within for `Calendar`
        `locale` - locale, `null` means use system default
      Throws:
        `java.lang.IllegalArgumentException` - if pattern is invalid or `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(java.lang.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:
        `java.lang.IllegalArgumentException` - if pattern is invalid

    - #### getInstance

          public static FastDateFormat getInstance(java.lang.String pattern,
                                                   java.util.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:
        `java.lang.IllegalArgumentException` - if pattern is invalid

    - #### getInstance

          public static FastDateFormat getInstance(java.lang.String pattern,
                                                   java.util.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:
        `java.lang.IllegalArgumentException` - if pattern is invalid

    - #### getInstance

          public static FastDateFormat getInstance(java.lang.String pattern,
                                                   java.util.TimeZone timeZone,
                                                   java.util.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:
        `java.lang.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:
        `java.lang.IllegalArgumentException` - if the Locale has no date pattern defined
      Since:
        2.1

    - #### getDateInstance

          public static FastDateFormat getDateInstance(int style,
                                                       java.util.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:
        `java.lang.IllegalArgumentException` - if the Locale has no date pattern defined
      Since:
        2.1

    - #### getDateInstance

          public static FastDateFormat getDateInstance(int style,
                                                       java.util.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:
        `java.lang.IllegalArgumentException` - if the Locale has no date pattern defined
      Since:
        2.1

    - #### getDateInstance

          public static FastDateFormat getDateInstance(int style,
                                                       java.util.TimeZone timeZone,
                                                       java.util.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:
        `java.lang.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:
        `java.lang.IllegalArgumentException` - if the Locale has no time pattern defined
      Since:
        2.1

    - #### getTimeInstance

          public static FastDateFormat getTimeInstance(int style,
                                                       java.util.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:
        `java.lang.IllegalArgumentException` - if the Locale has no time pattern defined
      Since:
        2.1

    - #### getTimeInstance

          public static FastDateFormat getTimeInstance(int style,
                                                       java.util.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:
        `java.lang.IllegalArgumentException` - if the Locale has no time pattern defined
      Since:
        2.1

    - #### getTimeInstance

          public static FastDateFormat getTimeInstance(int style,
                                                       java.util.TimeZone timeZone,
                                                       java.util.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:
        `java.lang.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:
        `java.lang.IllegalArgumentException` - if the Locale has no date/time pattern defined
      Since:
        2.1

    - #### getDateTimeInstance

          public static FastDateFormat getDateTimeInstance(int dateStyle,
                                                           int timeStyle,
                                                           java.util.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:
        `java.lang.IllegalArgumentException` - if the Locale has no date/time pattern defined
      Since:
        2.1

    - #### getDateTimeInstance

          public static FastDateFormat getDateTimeInstance(int dateStyle,
                                                           int timeStyle,
                                                           java.util.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:
        `java.lang.IllegalArgumentException` - if the Locale has no date/time pattern defined
      Since:
        2.1

    - #### getDateTimeInstance

          public static FastDateFormat getDateTimeInstance(int dateStyle,
                                                           int timeStyle,
                                                           java.util.TimeZone timeZone,
                                                           java.util.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:
        `java.lang.IllegalArgumentException` - if the Locale has no date/time pattern defined

    - #### init

          protected void init()

      Initializes the instance for first use.

    - #### parsePattern

          protected java.util.List parsePattern()

      Returns a list of Rules given a pattern.

      Returns:
        a `List` of Rule objects
      Throws:
        `java.lang.IllegalArgumentException` - if pattern is invalid

    - #### parseToken

          protected java.lang.String parseToken(java.lang.String pattern,
                                                int[] indexRef)

      Performs the parsing of tokens.

      Parameters:
        `pattern` - the pattern
        `indexRef` - index references
      Returns:
        parsed token

    - #### selectNumberRule

          protected org.apache.commons.lang.time.FastDateFormat.NumberRule selectNumberRule(int field,
                                                                                            int padding)

      Gets an appropriate rule for the padding required.

      Parameters:
        `field` - the field to get a rule for
        `padding` - the padding required
      Returns:
        a new rule with the correct padding

    - #### format

          public java.lang.StringBuffer format(java.lang.Object obj,
                                               java.lang.StringBuffer toAppendTo,
                                               java.text.FieldPosition pos)

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

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

    - #### format

          public java.lang.String format(long millis)

      Formats a millisecond `long` value.

      Parameters:
        `millis` - the millisecond value to format
      Returns:
        the formatted string
      Since:
        2.1

    - #### format

          public java.lang.String format(java.util.Date date)

      Formats a `Date` object.

      Parameters:
        `date` - the date to format
      Returns:
        the formatted string

    - #### format

          public java.lang.String format(java.util.Calendar calendar)

      Formats a `Calendar` object.

      Parameters:
        `calendar` - the calendar to format
      Returns:
        the formatted string

    - #### format

          public java.lang.StringBuffer format(long millis,
                                               java.lang.StringBuffer buf)

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

      Parameters:
        `millis` - the millisecond value to format
        `buf` - the buffer to format into
      Returns:
        the specified string buffer
      Since:
        2.1

    - #### format

          public java.lang.StringBuffer format(java.util.Date date,
                                               java.lang.StringBuffer buf)

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

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

    - #### format

          public java.lang.StringBuffer format(java.util.Calendar calendar,
                                               java.lang.StringBuffer buf)

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

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

    - #### applyRules

          protected java.lang.StringBuffer applyRules(java.util.Calendar calendar,
                                                      java.lang.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

    - #### parseObject

          public java.lang.Object parseObject(java.lang.String source,
                                              java.text.ParsePosition pos)

      Parsing is not supported.

      Specified by:
        `parseObject` in class `java.text.Format`
      Parameters:
        `source` - the string to parse
        `pos` - the parsing position
      Returns:
        `null` as not supported

    - #### getPattern

          public java.lang.String getPattern()

      Gets the pattern used by this formatter.

      Returns:
        the pattern, `SimpleDateFormat` compatible

    - #### getTimeZone

          public java.util.TimeZone getTimeZone()

      Gets the time zone used by this formatter.

      This zone is always used for `Date` formatting. If a `Calendar` is passed in to be formatted, the time zone on that may be used depending on `getTimeZoneOverridesCalendar()`.

      Returns:
        the time zone

    - #### getTimeZoneOverridesCalendar

          public boolean getTimeZoneOverridesCalendar()

      Returns `true` if the time zone of the calendar overrides the time zone of the formatter.

      Returns:
        `true` if time zone of formatter overridden for calendars

    - #### getLocale

          public java.util.Locale getLocale()

      Gets the locale used by this formatter.

      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(java.lang.Object obj)

      Compares two objects for equality.

      Overrides:
        `equals` in class `java.lang.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 `java.lang.Object`
      Returns:
        a hashcode compatible with equals

    - #### toString

          public java.lang.String toString()

      Gets a debugging string version of this formatter.

      Overrides:
        `toString` in class `java.lang.Object`
      Returns:
        a debugging string

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