java.text.Format
java.text.DateFormat
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java.lang.Object
DateFormat is an abstract class for date/time formatting subclasses which
formats and parses dates or time in a language-independent manner.
The date/time formatting subclass, such as SimpleDateFormat, allows for
formatting (i.e., date -> text), parsing (text -> date), and
normalization. The date is represented as a Date object or
as the milliseconds since January 1, 1970, 00:00:00 GMT.
DateFormat provides many class methods for obtaining default date/time formatters based on the default or a given locale and a number of formatting styles. The formatting styles include FULL, LONG, MEDIUM, and SHORT. More detail and examples of using these styles are provided in the method descriptions.
DateFormat helps you to format and parse dates for any locale. Your code can be completely independent of the locale conventions for months, days of the week, or even the calendar format: lunar vs. solar.
To format a date for the current Locale, use one of the static factory methods:
myString = DateFormat.getDateInstance().format(myDate);
If you are formatting multiple dates, it is more efficient to get the format and use it multiple times so that the system doesn't have to fetch the information about the local language and country conventions multiple times.
DateFormat df = DateFormat.getDateInstance();
for (int i = 0; i < a.length; ++i) {
output.println(df.format(myDate[i]) + "; ");
}
To format a date for a different Locale, specify it in the call to getDateInstance().
DateFormat df = DateFormat.getDateInstance(DateFormat.LONG, Locale.FRANCE);
You can use a DateFormat to parse also.
myDate = df.parse(myString);
Use getDateInstance to get the normal date format for that country. There are other static factory methods available. Use getTimeInstance to get the time format for that country. Use getDateTimeInstance to get a date and time format. You can pass in different options to these factory methods to control the length of the result; from SHORT to MEDIUM to LONG to FULL. The exact result depends on the locale, but generally:
You can also set the time zone on the format if you wish. If you want even more control over the format or parsing, (or want to give your users more control), you can try casting the DateFormat you get from the factory methods to a SimpleDateFormat. This will work for the majority of countries; just remember to put it in a try block in case you encounter an unusual one.
You can also use forms of the parse and format methods with ParsePosition and FieldPosition to allow you to
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.
Format,
NumberFormat,
SimpleDateFormat,
Calendar,
GregorianCalendar,
TimeZone,
Serialized Form| Nested Class Summary | |
static class |
DateFormat.Field
Defines constants that are used as attribute keys in the AttributedCharacterIterator returned
from DateFormat.formatToCharacterIterator and as
field identifiers in FieldPosition.
|
| Nested classes inherited from class java.text.Format |
Format.FieldDelegate |
| Field Summary | |
static int |
AM_PM_FIELD
Useful constant for AM_PM field alignment. |
protected Calendar |
calendar
The calendar that DateFormat uses to produce the time field
values needed to implement date and time formatting. |
static int |
DATE_FIELD
Useful constant for DATE field alignment. |
static int |
DAY_OF_WEEK_FIELD
Useful constant for DAY_OF_WEEK field alignment. |
static int |
DAY_OF_WEEK_IN_MONTH_FIELD
Useful constant for DAY_OF_WEEK_IN_MONTH field alignment. |
static int |
DAY_OF_YEAR_FIELD
Useful constant for DAY_OF_YEAR field alignment. |
static int |
DEFAULT
Constant for default style pattern. |
static int |
ERA_FIELD
Useful constant for ERA field alignment. |
static int |
FULL
Constant for full style pattern. |
static int |
HOUR_OF_DAY0_FIELD
Useful constant for zero-based HOUR_OF_DAY field alignment. |
static int |
HOUR_OF_DAY1_FIELD
Useful constant for one-based HOUR_OF_DAY field alignment. |
static int |
HOUR0_FIELD
Useful constant for zero-based HOUR field alignment. |
static int |
HOUR1_FIELD
Useful constant for one-based HOUR field alignment. |
static int |
LONG
Constant for long style pattern. |
static int |
MEDIUM
Constant for medium style pattern. |
static int |
MILLISECOND_FIELD
Useful constant for MILLISECOND field alignment. |
static int |
MINUTE_FIELD
Useful constant for MINUTE field alignment. |
static int |
MONTH_FIELD
Useful constant for MONTH field alignment. |
protected NumberFormat |
numberFormat
The number formatter that DateFormat uses to format numbers
in dates and times. |
static int |
SECOND_FIELD
Useful constant for SECOND field alignment. |
private static long |
serialVersionUID
|
static int |
SHORT
Constant for short style pattern. |
static int |
TIMEZONE_FIELD
Useful constant for TIMEZONE field alignment. |
static int |
WEEK_OF_MONTH_FIELD
Useful constant for WEEK_OF_MONTH field alignment. |
static int |
WEEK_OF_YEAR_FIELD
Useful constant for WEEK_OF_YEAR field alignment. |
static int |
YEAR_FIELD
Useful constant for YEAR field alignment. |
| Constructor Summary | |
protected |
DateFormat()
Create a new date format. |
| Method Summary | |
Object |
clone()
Overrides Cloneable |
boolean |
equals(Object obj)
Overrides equals |
String |
format(Date date)
Formats a Date into a date/time string. |
abstract StringBuffer |
format(Date date,
StringBuffer toAppendTo,
FieldPosition fieldPosition)
Formats a Date into a date/time string. |
StringBuffer |
format(Object obj,
StringBuffer toAppendTo,
FieldPosition fieldPosition)
Overrides Format. |
private static DateFormat |
get(int timeStyle,
int dateStyle,
int flags,
Locale loc)
Creates a DateFormat with the given time and/or date style in the given locale. |
static Locale[] |
getAvailableLocales()
Gets the set of locales for which DateFormats are installed. |
Calendar |
getCalendar()
Gets the calendar associated with this date/time formatter. |
static DateFormat |
getDateInstance()
Gets the date formatter with the default formatting style for the default locale. |
static DateFormat |
getDateInstance(int style)
Gets the date formatter with the given formatting style for the default locale. |
static DateFormat |
getDateInstance(int style,
Locale aLocale)
Gets the date formatter with the given formatting style for the given locale. |
static DateFormat |
getDateTimeInstance()
Gets the date/time formatter with the default formatting style for the default locale. |
static DateFormat |
getDateTimeInstance(int dateStyle,
int timeStyle)
Gets the date/time formatter with the given date and time formatting styles for the default locale. |
static DateFormat |
getDateTimeInstance(int dateStyle,
int timeStyle,
Locale aLocale)
Gets the date/time formatter with the given formatting styles for the given locale. |
static DateFormat |
getInstance()
Get a default date/time formatter that uses the SHORT style for both the date and the time. |
NumberFormat |
getNumberFormat()
Gets the number formatter which this date/time formatter uses to format and parse a time. |
static DateFormat |
getTimeInstance()
Gets the time formatter with the default formatting style for the default locale. |
static DateFormat |
getTimeInstance(int style)
Gets the time formatter with the given formatting style for the default locale. |
static DateFormat |
getTimeInstance(int style,
Locale aLocale)
Gets the time formatter with the given formatting style for the given locale. |
TimeZone |
getTimeZone()
Gets the time zone. |
int |
hashCode()
Overrides hashCode |
boolean |
isLenient()
Tell whether date/time parsing is to be lenient. |
Date |
parse(String source)
Parses text from the beginning of the given string to produce a date. |
abstract Date |
parse(String source,
ParsePosition pos)
Parse a date/time string according to the given parse position. |
Object |
parseObject(String source,
ParsePosition pos)
Parses text from a string to produce a Date.
|
void |
setCalendar(Calendar newCalendar)
Set the calendar to be used by this date format. |
void |
setLenient(boolean lenient)
Specify whether or not date/time parsing is to be lenient. |
void |
setNumberFormat(NumberFormat newNumberFormat)
Allows you to set the number formatter. |
void |
setTimeZone(TimeZone zone)
Sets the time zone for the calendar of this DateFormat object. |
| Methods inherited from class java.text.Format |
createAttributedCharacterIterator, createAttributedCharacterIterator, createAttributedCharacterIterator, createAttributedCharacterIterator, format, formatToCharacterIterator, parseObject |
| Methods inherited from class java.lang.Object |
finalize, getClass, notify, notifyAll, toString, wait, wait, wait |
| Field Detail |
protected Calendar calendar
DateFormat uses to produce the time field
values needed to implement date and time formatting. Subclasses should
initialize this to a calendar appropriate for the locale associated with
this DateFormat.
protected NumberFormat numberFormat
DateFormat uses to format numbers
in dates and times. Subclasses should initialize this to a number format
appropriate for the locale associated with this DateFormat.
public static final int ERA_FIELD
public static final int YEAR_FIELD
public static final int MONTH_FIELD
public static final int DATE_FIELD
public static final int HOUR_OF_DAY1_FIELD
public static final int HOUR_OF_DAY0_FIELD
public static final int MINUTE_FIELD
public static final int SECOND_FIELD
public static final int MILLISECOND_FIELD
public static final int DAY_OF_WEEK_FIELD
public static final int DAY_OF_YEAR_FIELD
public static final int DAY_OF_WEEK_IN_MONTH_FIELD
public static final int WEEK_OF_YEAR_FIELD
public static final int WEEK_OF_MONTH_FIELD
public static final int AM_PM_FIELD
public static final int HOUR1_FIELD
public static final int HOUR0_FIELD
public static final int TIMEZONE_FIELD
private static final long serialVersionUID
public static final int FULL
public static final int LONG
public static final int MEDIUM
public static final int SHORT
public static final int DEFAULT
| Constructor Detail |
protected DateFormat()
| Method Detail |
public final StringBuffer format(Object obj,
StringBuffer toAppendTo,
FieldPosition fieldPosition)
format in class Formatobj - must be a Number or a Date.toAppendTo - the string buffer for the returning time string.fieldPosition - keeps track of the position of the field
within the returned string.
On input: an alignment field,
if desired. On output: the offsets of the alignment field. For
example, given a time text "1996.07.10 AD at 15:08:56 PDT",
if the given fieldPosition is DateFormat.YEAR_FIELD, the
begin index and end index of fieldPosition will be set to
0 and 4, respectively.
Notice that if the same time field appears
more than once in a pattern, the fieldPosition will be set for the first
occurrence of that time field. For instance, formatting a Date to
the time string "1 PM PDT (Pacific Daylight Time)" using the pattern
"h a z (zzzz)" and the alignment field DateFormat.TIMEZONE_FIELD,
the begin index and end index of fieldPosition will be set to
5 and 8, respectively, for the first occurrence of the timezone
pattern character 'z'.
Format
public abstract StringBuffer format(Date date,
StringBuffer toAppendTo,
FieldPosition fieldPosition)
date - a Date to be formatted into a date/time string.toAppendTo - the string buffer for the returning date/time string.fieldPosition - keeps track of the position of the field
within the returned string.
On input: an alignment field,
if desired. On output: the offsets of the alignment field. For
example, given a time text "1996.07.10 AD at 15:08:56 PDT",
if the given fieldPosition is DateFormat.YEAR_FIELD, the
begin index and end index of fieldPosition will be set to
0 and 4, respectively.
Notice that if the same time field appears
more than once in a pattern, the fieldPosition will be set for the first
occurrence of that time field. For instance, formatting a Date to
the time string "1 PM PDT (Pacific Daylight Time)" using the pattern
"h a z (zzzz)" and the alignment field DateFormat.TIMEZONE_FIELD,
the begin index and end index of fieldPosition will be set to
5 and 8, respectively, for the first occurrence of the timezone
pattern character 'z'.
public final String format(Date date)
date - the time value to be formatted into a time string.
public Date parse(String source)
throws ParseException
See the parse(String, ParsePosition) method for more information
on date parsing.
source - A String whose beginning should be parsed.
Date parsed from the string.
ParseException - if the beginning of the specified string
cannot be parsed.
public abstract Date parse(String source,
ParsePosition pos)
By default, parsing is lenient: If the input is not in the form used by this object's format method but can still be parsed as a date, then the parse succeeds. Clients may insist on strict adherence to the format by calling setLenient(false).
source - The date/time string to be parsedpos - 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.
setLenient(boolean)
public Object parseObject(String source,
ParsePosition pos)
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.
See the parse(String, ParsePosition) method for more information
on date parsing.
parseObject in class Formatsource - A String, part of which should be parsed.pos - A ParsePosition object with index and error
index information as described above.
Date parsed from the string. In case of
error, returns null.
NullPointerException - if pos is null.public static final DateFormat getTimeInstance()
public static final DateFormat getTimeInstance(int style)
style - the given formatting style. For example,
SHORT for "h:mm a" in the US locale.
public static final DateFormat getTimeInstance(int style,
Locale aLocale)
style - the given formatting style. For example,
SHORT for "h:mm a" in the US locale.aLocale - the given locale.
public static final DateFormat getDateInstance()
public static final DateFormat getDateInstance(int style)
style - the given formatting style. For example,
SHORT for "M/d/yy" in the US locale.
public static final DateFormat getDateInstance(int style,
Locale aLocale)
style - the given formatting style. For example,
SHORT for "M/d/yy" in the US locale.aLocale - the given locale.
public static final DateFormat getDateTimeInstance()
public static final DateFormat getDateTimeInstance(int dateStyle,
int timeStyle)
dateStyle - the given date formatting style. For example,
SHORT for "M/d/yy" in the US locale.timeStyle - the given time formatting style. For example,
SHORT for "h:mm a" in the US locale.
public static final DateFormat getDateTimeInstance(int dateStyle,
int timeStyle,
Locale aLocale)
dateStyle - the given date formatting style.timeStyle - the given time formatting style.aLocale - the given locale.
public static final DateFormat getInstance()
public static Locale[] getAvailableLocales()
public void setCalendar(Calendar newCalendar)
newCalendar - the new Calendar to be used by the date formatpublic Calendar getCalendar()
public void setNumberFormat(NumberFormat newNumberFormat)
newNumberFormat - the given new NumberFormat.public NumberFormat getNumberFormat()
public void setTimeZone(TimeZone zone)
zone - the given new time zone.public TimeZone getTimeZone()
public void setLenient(boolean lenient)
lenient - when true, parsing is lenientCalendar.setLenient(boolean)public boolean isLenient()
public int hashCode()
hashCode in class ObjectObject.equals(java.lang.Object),
Hashtablepublic boolean equals(Object obj)
equals in class Objectobj - the reference object with which to compare.
true if this object is the same as the obj
argument; false otherwise.Object.hashCode(),
Hashtablepublic Object clone()
clone in class Format
private static DateFormat get(int timeStyle,
int dateStyle,
int flags,
Locale loc)
timeStyle - a value from 0 to 3 indicating the time format,
ignored if flags is 2dateStyle - a value from 0 to 3 indicating the time format,
ignored if flags is 1flags - either 1 for a time format, 2 for a date format,
or 3 for a date/time formatloc - the locale for the format
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