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DateFormat.javaAPI DocJava SE 6 API35953Tue Jun 10 00:25:50 BST 2008java.text

DateFormat

public 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.

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
Format
see
NumberFormat
see
SimpleDateFormat
see
java.util.Calendar
see
java.util.GregorianCalendar
see
java.util.TimeZone
version
1.57 11/17/05
author
Mark Davis, Chen-Lieh Huang, Alan Liu

Fields Summary
protected Calendar
calendar
The 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
numberFormat
The 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_FIELD
Useful constant for ERA field alignment. Used in FieldPosition of date/time formatting.
public static final int
YEAR_FIELD
Useful constant for YEAR field alignment. Used in FieldPosition of date/time formatting.
public static final int
MONTH_FIELD
Useful constant for MONTH field alignment. Used in FieldPosition of date/time formatting.
public static final int
DATE_FIELD
Useful constant for DATE field alignment. Used in FieldPosition of date/time formatting.
public static final int
HOUR_OF_DAY1_FIELD
Useful 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_FIELD
Useful 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_FIELD
Useful constant for MINUTE field alignment. Used in FieldPosition of date/time formatting.
public static final int
SECOND_FIELD
Useful constant for SECOND field alignment. Used in FieldPosition of date/time formatting.
public static final int
MILLISECOND_FIELD
Useful constant for MILLISECOND field alignment. Used in FieldPosition of date/time formatting.
public static final int
DAY_OF_WEEK_FIELD
Useful constant for DAY_OF_WEEK field alignment. Used in FieldPosition of date/time formatting.
public static final int
DAY_OF_YEAR_FIELD
Useful constant for DAY_OF_YEAR field alignment. Used in FieldPosition of date/time formatting.
public static final int
DAY_OF_WEEK_IN_MONTH_FIELD
Useful constant for DAY_OF_WEEK_IN_MONTH field alignment. Used in FieldPosition of date/time formatting.
public static final int
WEEK_OF_YEAR_FIELD
Useful constant for WEEK_OF_YEAR field alignment. Used in FieldPosition of date/time formatting.
public static final int
WEEK_OF_MONTH_FIELD
Useful constant for WEEK_OF_MONTH field alignment. Used in FieldPosition of date/time formatting.
public static final int
AM_PM_FIELD
Useful constant for AM_PM field alignment. Used in FieldPosition of date/time formatting.
public static final int
HOUR1_FIELD
Useful 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_FIELD
Useful 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_FIELD
Useful constant for TIMEZONE field alignment. Used in FieldPosition of date/time formatting.
private static final long
serialVersionUID
public static final int
FULL
Constant for full style pattern.
public static final int
LONG
Constant for long style pattern.
public static final int
MEDIUM
Constant for medium style pattern.
public static final int
SHORT
Constant for short style pattern.
public static final int
DEFAULT
Constant for default style pattern. Its value is MEDIUM.
Constructors Summary
protected DateFormat()
Create a new date format.

Methods Summary
public java.lang.Objectclone()
Overrides Cloneable

        DateFormat other = (DateFormat) super.clone();
        other.calendar = (Calendar) calendar.clone();
        other.numberFormat = (NumberFormat) numberFormat.clone();
        return other;
    
public booleanequals(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.StringBufferformat(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.

param
obj must be a Number or a Date.
param
toAppendTo the string buffer for the returning time string.
return
the string buffer passed in as toAppendTo, with formatted text appended.
param
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'.
see
java.text.Format


                                                                                                                                                                                                                 
          
                                      
    
        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.StringBufferformat(java.util.Date date, java.lang.StringBuffer toAppendTo, java.text.FieldPosition fieldPosition)
Formats a Date into a date/time string.

param
date a Date to be formatted into a date/time string.
param
toAppendTo the string buffer for the returning date/time string.
param
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'.
return
the string buffer passed in as toAppendTo, with formatted text appended.

public final java.lang.Stringformat(java.util.Date date)
Formats a Date into a date/time string.

param
date the time value to be formatted into a time string.
return
the formatted time string.

        return format(date, new StringBuffer(),
		      DontCareFieldPosition.INSTANCE).toString();
    
private static java.text.DateFormatget(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.

param
timeStyle a value from 0 to 3 indicating the time format, ignored if flags is 2
param
dateStyle a value from 0 to 3 indicating the time format, ignored if flags is 1
param
flags either 1 for a time format, 2 for a date format, or 3 for a date/time format
param
loc the locale for the format

        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}.

return
An array of locales for which localized DateFormat instances are available.

        LocaleServiceProviderPool pool = 
            LocaleServiceProviderPool.getPool(DateFormatProvider.class);
	return pool.getAvailableLocales();
    
public java.util.CalendargetCalendar()
Gets the calendar associated with this date/time formatter.

return
the calendar associated with this date/time formatter.

        return calendar;
    
public static final java.text.DateFormatgetDateInstance()
Gets the date formatter with the default formatting style for the default locale.

return
a date formatter.

        return get(0, DEFAULT, 2, Locale.getDefault());
    
public static final java.text.DateFormatgetDateInstance(int style)
Gets the date formatter with the given formatting style for the default locale.

param
style the given formatting style. For example, SHORT for "M/d/yy" in the US locale.
return
a date formatter.

        return get(0, style, 2, Locale.getDefault());
    
public static final java.text.DateFormatgetDateInstance(int style, java.util.Locale aLocale)
Gets the date formatter with the given formatting style for the given locale.

param
style the given formatting style. For example, SHORT for "M/d/yy" in the US locale.
param
aLocale the given locale.
return
a date formatter.

        return get(0, style, 2, aLocale);
    
public static final java.text.DateFormatgetDateTimeInstance()
Gets the date/time formatter with the default formatting style for the default locale.

return
a date/time formatter.

        return get(DEFAULT, DEFAULT, 3, Locale.getDefault());
    
public static final java.text.DateFormatgetDateTimeInstance(int dateStyle, int timeStyle)
Gets the date/time formatter with the given date and time formatting styles for the default locale.

param
dateStyle the given date formatting style. For example, SHORT for "M/d/yy" in the US locale.
param
timeStyle the given time formatting style. For example, SHORT for "h:mm a" in the US locale.
return
a date/time formatter.

        return get(timeStyle, dateStyle, 3, Locale.getDefault());
    
public static final java.text.DateFormatgetDateTimeInstance(int dateStyle, int timeStyle, java.util.Locale aLocale)
Gets the date/time formatter with the given formatting styles for the given locale.

param
dateStyle the given date formatting style.
param
timeStyle the given time formatting style.
param
aLocale the given locale.
return
a date/time formatter.

        return get(timeStyle, dateStyle, 3, aLocale);
    
public static final java.text.DateFormatgetInstance()
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.NumberFormatgetNumberFormat()
Gets the number formatter which this date/time formatter uses to format and parse a time.

return
the number formatter which this date/time formatter uses.

        return numberFormat;
    
public static final java.text.DateFormatgetTimeInstance()
Gets the time formatter with the default formatting style for the default locale.

return
a time formatter.


                          
        
    
        return get(DEFAULT, 0, 1, Locale.getDefault());
    
public static final java.text.DateFormatgetTimeInstance(int style)
Gets the time formatter with the given formatting style for the default locale.

param
style the given formatting style. For example, SHORT for "h:mm a" in the US locale.
return
a time formatter.

        return get(style, 0, 1, Locale.getDefault());
    
public static final java.text.DateFormatgetTimeInstance(int style, java.util.Locale aLocale)
Gets the time formatter with the given formatting style for the given locale.

param
style the given formatting style. For example, SHORT for "h:mm a" in the US locale.
param
aLocale the given locale.
return
a time formatter.

        return get(style, 0, 1, aLocale);
    
public java.util.TimeZonegetTimeZone()
Gets the time zone.

return
the time zone associated with the calendar of DateFormat.

        return calendar.getTimeZone();
    
public inthashCode()
Overrides hashCode

        return numberFormat.hashCode();
        // just enough fields for a reasonable distribution
    
public booleanisLenient()
Tell whether date/time parsing is to be lenient.

        return calendar.isLenient();
    
public java.util.Dateparse(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.

param
source A String whose beginning should be parsed.
return
A Date parsed from the string.
exception
ParseException if the beginning of the specified string cannot be parsed.

        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.Dateparse(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).

see
java.text.DateFormat#setLenient(boolean)
param
source The date/time string to be parsed
param
pos 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.
return
A Date, or null if the input could not be parsed

public java.lang.ObjectparseObject(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.

param
source A String, part of which should be parsed.
param
pos A ParsePosition object with index and error index information as described above.
return
A Date parsed from the string. In case of error, returns null.
exception
NullPointerException if pos is null.

        return parse(source, pos);
    
public voidsetCalendar(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.

param
newCalendar the new Calendar to be used by the date format

        this.calendar = newCalendar;
    
public voidsetLenient(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.

param
lenient when true, parsing is lenient
see
java.util.Calendar#setLenient

        calendar.setLenient(lenient);
    
public voidsetNumberFormat(java.text.NumberFormat newNumberFormat)
Allows you to set the number formatter.

param
newNumberFormat the given new NumberFormat.

        this.numberFormat = newNumberFormat;
    
public voidsetTimeZone(java.util.TimeZone zone)
Sets the time zone for the calendar of this DateFormat object.

param
zone the given new time zone.

        calendar.setTimeZone(zone);