DateFormatpublic abstract class DateFormat extends Format 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 < myDate.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:
- SHORT is completely numeric, such as 12.13.52 or 3:30pm
- MEDIUM is longer, such as Jan 12, 1952
- LONG is longer, such as January 12, 1952 or 3:30:32pm
- FULL is pretty completely specified, such as
Tuesday, April 12, 1952 AD or 3:30:42pm PST.
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
- progressively parse through pieces of a string.
- align any particular field, or find out where it is for selection
on the screen.
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. |
Fields Summary |
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protected Calendar | calendarThe calendar that 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 | numberFormatThe number formatter that 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_FIELDUseful constant for ERA field alignment.
Used in FieldPosition of date/time formatting. | public static final int | YEAR_FIELDUseful constant for YEAR field alignment.
Used in FieldPosition of date/time formatting. | public static final int | MONTH_FIELDUseful constant for MONTH field alignment.
Used in FieldPosition of date/time formatting. | public static final int | DATE_FIELDUseful constant for DATE field alignment.
Used in FieldPosition of date/time formatting. | public static final int | HOUR_OF_DAY1_FIELDUseful constant for one-based HOUR_OF_DAY field alignment.
Used in FieldPosition of date/time formatting.
HOUR_OF_DAY1_FIELD is used for the one-based 24-hour clock.
For example, 23:59 + 01:00 results in 24:59. | public static final int | HOUR_OF_DAY0_FIELDUseful constant for zero-based HOUR_OF_DAY field alignment.
Used in FieldPosition of date/time formatting.
HOUR_OF_DAY0_FIELD is used for the zero-based 24-hour clock.
For example, 23:59 + 01:00 results in 00:59. | public static final int | MINUTE_FIELDUseful constant for MINUTE field alignment.
Used in FieldPosition of date/time formatting. | public static final int | SECOND_FIELDUseful constant for SECOND field alignment.
Used in FieldPosition of date/time formatting. | public static final int | MILLISECOND_FIELDUseful constant for MILLISECOND field alignment.
Used in FieldPosition of date/time formatting. | public static final int | DAY_OF_WEEK_FIELDUseful constant for DAY_OF_WEEK field alignment.
Used in FieldPosition of date/time formatting. | public static final int | DAY_OF_YEAR_FIELDUseful constant for DAY_OF_YEAR field alignment.
Used in FieldPosition of date/time formatting. | public static final int | DAY_OF_WEEK_IN_MONTH_FIELDUseful constant for DAY_OF_WEEK_IN_MONTH field alignment.
Used in FieldPosition of date/time formatting. | public static final int | WEEK_OF_YEAR_FIELDUseful constant for WEEK_OF_YEAR field alignment.
Used in FieldPosition of date/time formatting. | public static final int | WEEK_OF_MONTH_FIELDUseful constant for WEEK_OF_MONTH field alignment.
Used in FieldPosition of date/time formatting. | public static final int | AM_PM_FIELDUseful constant for AM_PM field alignment.
Used in FieldPosition of date/time formatting. | public static final int | HOUR1_FIELDUseful constant for one-based HOUR field alignment.
Used in FieldPosition of date/time formatting.
HOUR1_FIELD is used for the one-based 12-hour clock.
For example, 11:30 PM + 1 hour results in 12:30 AM. | public static final int | HOUR0_FIELDUseful constant for zero-based HOUR field alignment.
Used in FieldPosition of date/time formatting.
HOUR0_FIELD is used for the zero-based 12-hour clock.
For example, 11:30 PM + 1 hour results in 00:30 AM. | public static final int | TIMEZONE_FIELDUseful constant for TIMEZONE field alignment.
Used in FieldPosition of date/time formatting. | private static final long | serialVersionUID | public static final int | FULLConstant for full style pattern. | public static final int | LONGConstant for long style pattern. | public static final int | MEDIUMConstant for medium style pattern. | public static final int | SHORTConstant for short style pattern. | public static final int | DEFAULTConstant for default style pattern. Its value is MEDIUM. |
Constructors Summary |
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protected DateFormat()Create a new date format.
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Methods Summary |
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public java.lang.Object | clone()Overrides Cloneable
DateFormat other = (DateFormat) super.clone();
other.calendar = (Calendar) calendar.clone();
other.numberFormat = (NumberFormat) numberFormat.clone();
return other;
| public boolean | equals(java.lang.Object obj)Overrides equals
if (this == obj) return true;
if (obj == null || getClass() != obj.getClass()) return false;
DateFormat other = (DateFormat) obj;
return (// calendar.equivalentTo(other.calendar) // THIS API DOESN'T EXIST YET!
calendar.getFirstDayOfWeek() == other.calendar.getFirstDayOfWeek() &&
calendar.getMinimalDaysInFirstWeek() == other.calendar.getMinimalDaysInFirstWeek() &&
calendar.isLenient() == other.calendar.isLenient() &&
calendar.getTimeZone().equals(other.calendar.getTimeZone()) &&
numberFormat.equals(other.numberFormat));
| public final java.lang.StringBuffer | format(java.lang.Object obj, java.lang.StringBuffer toAppendTo, java.text.FieldPosition fieldPosition)Overrides Format.
Formats a time object into a time string. Examples of time objects
are a time value expressed in milliseconds and a Date object.
if (obj instanceof Date)
return format( (Date)obj, toAppendTo, fieldPosition );
else if (obj instanceof Number)
return format( new Date(((Number)obj).longValue()),
toAppendTo, fieldPosition );
else
throw new IllegalArgumentException("Cannot format given Object as a Date");
| public abstract java.lang.StringBuffer | format(java.util.Date date, java.lang.StringBuffer toAppendTo, java.text.FieldPosition fieldPosition)Formats a Date into a date/time string.
| public final java.lang.String | format(java.util.Date date)Formats a Date into a date/time string.
return format(date, new StringBuffer(),
DontCareFieldPosition.INSTANCE).toString();
| private static java.text.DateFormat | get(int timeStyle, int dateStyle, int flags, java.util.Locale loc)Creates a DateFormat with the given time and/or date style in the given
locale.
if ((flags & 1) != 0) {
if (timeStyle < 0 || timeStyle > 3) {
throw new IllegalArgumentException("Illegal time style " + timeStyle);
}
} else {
timeStyle = -1;
}
if ((flags & 2) != 0) {
if (dateStyle < 0 || dateStyle > 3) {
throw new IllegalArgumentException("Illegal date style " + dateStyle);
}
} else {
dateStyle = -1;
}
try {
// Check whether a provider can provide an implementation that's closer
// to the requested locale than what the Java runtime itself can provide.
LocaleServiceProviderPool pool =
LocaleServiceProviderPool.getPool(DateFormatProvider.class);
if (pool.hasProviders()) {
DateFormat providersInstance = pool.getLocalizedObject(
DateFormatGetter.INSTANCE,
loc,
timeStyle,
dateStyle,
flags);
if (providersInstance != null) {
return providersInstance;
}
}
return new SimpleDateFormat(timeStyle, dateStyle, loc);
} catch (MissingResourceException e) {
return new SimpleDateFormat("M/d/yy h:mm a");
}
| public static java.util.Locale[] | getAvailableLocales()Returns an array of all locales for which the
get*Instance methods of this class can return
localized instances.
The returned array represents the union of locales supported by the Java
runtime and by installed
{@link java.text.spi.DateFormatProvider DateFormatProvider} implementations.
It must contain at least a Locale instance equal to
{@link java.util.Locale#US Locale.US}.
LocaleServiceProviderPool pool =
LocaleServiceProviderPool.getPool(DateFormatProvider.class);
return pool.getAvailableLocales();
| public java.util.Calendar | getCalendar()Gets the calendar associated with this date/time formatter.
return calendar;
| public static final java.text.DateFormat | getDateInstance()Gets the date formatter with the default formatting style
for the default locale.
return get(0, DEFAULT, 2, Locale.getDefault());
| public static final java.text.DateFormat | getDateInstance(int style)Gets the date formatter with the given formatting style
for the default locale.
return get(0, style, 2, Locale.getDefault());
| public static final java.text.DateFormat | getDateInstance(int style, java.util.Locale aLocale)Gets the date formatter with the given formatting style
for the given locale.
return get(0, style, 2, aLocale);
| public static final java.text.DateFormat | getDateTimeInstance()Gets the date/time formatter with the default formatting style
for the default locale.
return get(DEFAULT, DEFAULT, 3, Locale.getDefault());
| public static final java.text.DateFormat | getDateTimeInstance(int dateStyle, int timeStyle)Gets the date/time formatter with the given date and time
formatting styles for the default locale.
return get(timeStyle, dateStyle, 3, Locale.getDefault());
| public static final java.text.DateFormat | getDateTimeInstance(int dateStyle, int timeStyle, java.util.Locale aLocale)Gets the date/time formatter with the given formatting styles
for the given locale.
return get(timeStyle, dateStyle, 3, aLocale);
| public static final java.text.DateFormat | getInstance()Get a default date/time formatter that uses the SHORT style for both the
date and the time.
return getDateTimeInstance(SHORT, SHORT);
| public java.text.NumberFormat | getNumberFormat()Gets the number formatter which this date/time formatter uses to
format and parse a time.
return numberFormat;
| public static final java.text.DateFormat | getTimeInstance()Gets the time formatter with the default formatting style
for the default locale.
return get(DEFAULT, 0, 1, Locale.getDefault());
| public static final java.text.DateFormat | getTimeInstance(int style)Gets the time formatter with the given formatting style
for the default locale.
return get(style, 0, 1, Locale.getDefault());
| public static final java.text.DateFormat | getTimeInstance(int style, java.util.Locale aLocale)Gets the time formatter with the given formatting style
for the given locale.
return get(style, 0, 1, aLocale);
| public java.util.TimeZone | getTimeZone()Gets the time zone.
return calendar.getTimeZone();
| public int | hashCode()Overrides hashCode
return numberFormat.hashCode();
// just enough fields for a reasonable distribution
| public boolean | isLenient()Tell whether date/time parsing is to be lenient.
return calendar.isLenient();
| public java.util.Date | parse(java.lang.String source)Parses text from the beginning of the given string to produce a date.
The method may not use the entire text of the given string.
See the {@link #parse(String, ParsePosition)} method for more information
on date parsing.
ParsePosition pos = new ParsePosition(0);
Date result = parse(source, pos);
if (pos.index == 0)
throw new ParseException("Unparseable date: \"" + source + "\"" ,
pos.errorIndex);
return result;
| public abstract java.util.Date | parse(java.lang.String source, java.text.ParsePosition pos)Parse a date/time string according to the given parse position. For
example, a time text "07/10/96 4:5 PM, PDT" will be parsed into a Date
that is equivalent to Date(837039928046).
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).
| public java.lang.Object | parseObject(java.lang.String source, java.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.
See the {@link #parse(String, ParsePosition)} method for more information
on date parsing.
return parse(source, pos);
| public void | setCalendar(java.util.Calendar newCalendar)Set the calendar to be used by this date format. Initially, the default
calendar for the specified or default locale is used.
this.calendar = newCalendar;
| public void | setLenient(boolean lenient)Specify whether or not date/time parsing is to be lenient. With
lenient parsing, the parser may use heuristics to interpret inputs that
do not precisely match this object's format. With strict parsing,
inputs must match this object's format.
calendar.setLenient(lenient);
| public void | setNumberFormat(java.text.NumberFormat newNumberFormat)Allows you to set the number formatter.
this.numberFormat = newNumberFormat;
| public void | setTimeZone(java.util.TimeZone zone)Sets the time zone for the calendar of this DateFormat object.
calendar.setTimeZone(zone);
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