SimpleDateFormat (Java 2 Platform SE 5.0) - JDK 5 Documentation v1.5.0, Java 2 SDK 英文文档

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java.text
Class SimpleDateFormat

java.lang.Object
  java.text.Format
      java.text.DateFormat
          java.text.SimpleDateFormat

All Implemented Interfaces:: Serializable, Cloneable

public class SimpleDateFormat
extends DateFormat
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
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 in week Text Tuesday; Tue
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
z Time zone General time zone Pacific Standard Time; PST; GMT-08:00
Z Time zone RFC 822 time zone -0800

Letter	Date or Time Component	Presentation	Examples
`G`	Era designator	Text	`AD`
`y`	Year	Year	`1996`; `96`
`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 in week	Text	`Tuesday`; `Tue`
`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`
`z`	Time zone	General time zone	`Pacific Standard Time`; `PST`; `GMT-08:00`
`Z`	Time zone	RFC 822 time zone	`-0800`

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: 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.
Month: If the number of pattern letters is 3 or more, the month is interpreted as text; otherwise, it is interpreted as a number.
General time zone: Time zones are interpreted as text if they have names. For time zones representing a GMT offset value, the following syntax is used:
```
     GMTOffsetTimeZone:
             GMT Sign Hours : Minutes
     Sign: one of
             + -
     Hours:
             Digit
             Digit Digit
     Minutes:
             Digit Digit
     Digit: one of
             0 1 2 3 4 5 6 7 8 9
```
Hours must be between 0 and 23, and Minutes 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:
             Sign TwoDigitHours Minutes
     TwoDigitHours:
             Digit Digit
```
TwoDigitHours must be between 00 and 23. Other definitions are as for general time zones.
For parsing, general time zones are also accepted.

SimpleDateFormat also supports localized 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.

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

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`

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, TimeZone, DateFormat, DateFormatSymbols, Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class java.text.DateFormat

DateFormat.Field

Field Summary

Fields inherited from class java.text.DateFormat

AM_PM_FIELD, calendar, DATE_FIELD, DAY_OF_WEEK_FIELD, DAY_OF_WEEK_IN_MONTH_FIELD, DAY_OF_YEAR_FIELD, DEFAULT, ERA_FIELD, FULL, HOUR_OF_DAY0_FIELD, HOUR_OF_DAY1_FIELD, HOUR0_FIELD, HOUR1_FIELD, LONG, MEDIUM, MILLISECOND_FIELD, MINUTE_FIELD, MONTH_FIELD, numberFormat, SECOND_FIELD, SHORT, TIMEZONE_FIELD, WEEK_OF_MONTH_FIELD, WEEK_OF_YEAR_FIELD, YEAR_FIELD

Constructor Summary

SimpleDateFormat()
          Constructs a SimpleDateFormat using the default pattern and date format symbols for the default locale.

SimpleDateFormat(String pattern)
          Constructs a SimpleDateFormat using the given pattern and the default date format symbols for the default locale.

SimpleDateFormat(String pattern, DateFormatSymbols formatSymbols)
          Constructs a SimpleDateFormat using the given pattern and date format symbols.

SimpleDateFormat(String pattern, Locale locale)
          Constructs a SimpleDateFormat using the given pattern and the default date format symbols for the given locale.

Method Summary

void applyLocalizedPattern(String pattern)
          Applies the given localized pattern string to this date format.

void applyPattern(String pattern)
          Applies the given pattern string to this date format.

Object clone()
          Creates a copy of this SimpleDateFormat.

boolean equals(Object obj)
          Compares the given object with this SimpleDateFormat for equality.

StringBuffer format(Date date, StringBuffer toAppendTo, FieldPosition pos)
          Formats the given Date into a date/time string and appends the result to the given StringBuffer.

AttributedCharacterIterator formatToCharacterIterator(Object obj)
          Formats an Object producing an AttributedCharacterIterator.

Date get2DigitYearStart()
          Returns the beginning date of the 100-year period 2-digit years are interpreted as being within.

DateFormatSymbols getDateFormatSymbols()
          Gets a copy of the date and time format symbols of this date format.

int hashCode()
          Returns the hash code value for this SimpleDateFormat object.

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

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.

void setDateFormatSymbols(DateFormatSymbols newFormatSymbols)
          Sets the date and time format symbols of this date format.

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

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

Methods inherited from class java.text.DateFormat

format, format, getAvailableLocales, getCalendar, getDateInstance, getDateInstance, getDateInstance, getDateTimeInstance, getDateTimeInstance, getDateTimeInstance, getInstance, getNumberFormat, getTimeInstance, getTimeInstance, getTimeInstance, getTimeZone, isLenient, parse, parseObject, setCalendar, setLenient, setNumberFormat, setTimeZone

Methods inherited from class java.text.Format

format, parseObject

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Nested classes/interfaces inherited from class java.text.DateFormat
`DateFormat.Field`

Fields inherited from class java.text.DateFormat
`AM_PM_FIELD, calendar, DATE_FIELD, DAY_OF_WEEK_FIELD, DAY_OF_WEEK_IN_MONTH_FIELD, DAY_OF_YEAR_FIELD, DEFAULT, ERA_FIELD, FULL, HOUR_OF_DAY0_FIELD, HOUR_OF_DAY1_FIELD, HOUR0_FIELD, HOUR1_FIELD, LONG, MEDIUM, MILLISECOND_FIELD, MINUTE_FIELD, MONTH_FIELD, numberFormat, SECOND_FIELD, SHORT, TIMEZONE_FIELD, WEEK_OF_MONTH_FIELD, WEEK_OF_YEAR_FIELD, YEAR_FIELD`

Constructor Summary
`SimpleDateFormat()` Constructs a `SimpleDateFormat` using the default pattern and date format symbols for the default locale.
`SimpleDateFormat(String pattern)` Constructs a `SimpleDateFormat` using the given pattern and the default date format symbols for the default locale.
`SimpleDateFormat(String pattern, DateFormatSymbols formatSymbols)` Constructs a `SimpleDateFormat` using the given pattern and date format symbols.
`SimpleDateFormat(String pattern, Locale locale)` Constructs a `SimpleDateFormat` using the given pattern and the default date format symbols for the given locale.

Method Summary
`void`	`applyLocalizedPattern(String pattern)` Applies the given localized pattern string to this date format.
`void`	`applyPattern(String pattern)` Applies the given pattern string to this date format.
`Object`	`clone()` Creates a copy of this `SimpleDateFormat`.
`boolean`	`equals(Object obj)` Compares the given object with this `SimpleDateFormat` for equality.
`StringBuffer`	`format(Date date, StringBuffer toAppendTo, FieldPosition pos)` Formats the given `Date` into a date/time string and appends the result to the given `StringBuffer`.
`AttributedCharacterIterator`	`formatToCharacterIterator(Object obj)` Formats an Object producing an `AttributedCharacterIterator`.
`Date`	`get2DigitYearStart()` Returns the beginning date of the 100-year period 2-digit years are interpreted as being within.
`DateFormatSymbols`	`getDateFormatSymbols()` Gets a copy of the date and time format symbols of this date format.
`int`	`hashCode()` Returns the hash code value for this `SimpleDateFormat` object.
`Date`	`parse(String text, ParsePosition pos)` Parses text from a string to produce a `Date`.
`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.
`void`	`setDateFormatSymbols(DateFormatSymbols newFormatSymbols)` Sets the date and time format symbols of this date format.
`String`	`toLocalizedPattern()` Returns a localized pattern string describing this date format.
`String`	`toPattern()` Returns a pattern string describing this date format.

Methods inherited from class java.text.DateFormat
`format, format, getAvailableLocales, getCalendar, getDateInstance, getDateInstance, getDateInstance, getDateTimeInstance, getDateTimeInstance, getDateTimeInstance, getInstance, getNumberFormat, getTimeInstance, getTimeInstance, getTimeInstance, getTimeZone, isLenient, parse, parseObject, setCalendar, setLenient, setNumberFormat, setTimeZone`

Methods inherited from class java.text.Format
`format, parseObject`

Methods inherited from class java.lang.Object
`finalize, getClass, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

SimpleDateFormat

public SimpleDateFormat()

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

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,
                        Locale locale)

Constructs a SimpleDateFormat 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 the DateFormat 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 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

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.
Since:: 1.2
See Also:: get2DigitYearStart()

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:: set2DigitYearStart(java.util.Date)

format

public StringBuffer format(Date date,
                           StringBuffer toAppendTo,
                           FieldPosition pos)

Formats the given Date into a date/time string and appends the result to the given StringBuffer.

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 - the formatting position. On input: an alignment field, if desired. On output: the offsets of the alignment field.
Returns:: the formatted date-time string.
Throws:: NullPointerException - if the given date is null

formatToCharacterIterator

public AttributedCharacterIterator formatToCharacterIterator(Object obj)

Formats an Object producing an AttributedCharacterIterator. You can use the returned AttributedCharacterIterator to build the resulting String, as well as to determine information about the resulting String.

Each attribute key of the AttributedCharacterIterator will be of type DateFormat.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 a Date.

The method attempts to parse text starting at the index given by pos. If parsing succeeds, then the index of pos 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 updated pos can be used to indicate the starting point for the next call to this method. If an error occurs, then the index of pos is not changed, the error index of pos is set to the index of the character where the error occurred, and null is returned.

Specified by:: parse in class DateFormat

Parameters:: text - 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.
Throws:: NullPointerException - if text or pos is null.
See Also:: DateFormat.setLenient(boolean)

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(java.text.DateFormatSymbols)

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()

clone

public Object clone()

Creates a copy of this SimpleDateFormat. This also clones the format's date format symbols.

Overrides:: clone in class DateFormat

Returns:: a clone of this SimpleDateFormat
See Also:: Cloneable

hashCode

public int hashCode()

Returns the hash code value for this SimpleDateFormat object.

Overrides:: hashCode in class DateFormat

Returns:: the hash code value for this SimpleDateFormat object.
See Also:: Object.equals(java.lang.Object), Hashtable

equals

public boolean equals(Object obj)

Compares the given object with this SimpleDateFormat for equality.

Overrides:: equals in class DateFormat

Parameters:: obj - the reference object with which to compare.
Returns:: true if the given object is equal to this SimpleDateFormat
See Also:: Object.hashCode(), Hashtable

Overview

Package

Class

Use

Tree

Deprecated

Index

Help

Java^TM 2 Platform
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Submit a bug or feature
For further API reference and developer documentation, see Java 2 SDK SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.

SimpleDateFormat (Java 2 Platform SE 5.0) - JDK 5 Documentation v1.5.0, Java 2 SDK 英文文档

java.text Class SimpleDateFormat

Date and Time Patterns

Examples

Synchronization

SimpleDateFormat

SimpleDateFormat

SimpleDateFormat

SimpleDateFormat

set2DigitYearStart

get2DigitYearStart

format

formatToCharacterIterator

parse

toPattern

toLocalizedPattern

applyPattern

applyLocalizedPattern

getDateFormatSymbols

setDateFormatSymbols

clone

hashCode

equals

java.text
Class SimpleDateFormat