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
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| Modifier and Type | Class and Description |
|---|---|
static class |
DateFormat.Field Defines constants that are used as attribute keys in the |
protected Calendar calendar
The Calendar instance used for calculating the date-time fields and the instant of time. This field is used for both formatting and parsing.
Subclasses should initialize this field 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.
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.
protected DateFormat()
Create a new date format.
public final StringBuffer format(Object obj,
StringBuffer toAppendTo,
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.
format in class Format
obj - 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'.Formatpublic abstract StringBuffer format(Date date,
StringBuffer toAppendTo,
FieldPosition fieldPosition) Formats a Date into a date/time string.
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)
Formats a Date into a date/time string.
date - the time value to be formatted into a time string.public Date parse(String source)
throws ParseException 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 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) 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(837039900000L).
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).
This parsing operation uses the calendar to produce a Date. As a result, the calendar's date-time fields and the TimeZone value may have been overwritten, depending on subclass implementations. Any TimeZone value that has previously been set by a call to setTimeZone may need to be restored for further operations.
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.Date, or null if the input could not be parsedpublic Object parseObject(String source,
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 parse(String, ParsePosition) method for more information on date parsing.
parseObject in class Format
source - 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()
Gets the time formatter with the default formatting style for the default FORMAT locale.
This is equivalent to calling getTimeInstance(DEFAULT,
Locale.getDefault(Locale.Category.FORMAT)).
Locale.getDefault(java.util.Locale.Category), Locale.Category.FORMAT
public static final DateFormat getTimeInstance(int style)
Gets the time formatter with the given formatting style for the default FORMAT locale.
This is equivalent to calling getTimeInstance(style,
Locale.getDefault(Locale.Category.FORMAT)).
style - the given formatting style. For example, SHORT for "h:mm a" in the US locale.Locale.getDefault(java.util.Locale.Category), Locale.Category.FORMAT
public static final DateFormat getTimeInstance(int style,
Locale aLocale) Gets the time formatter with the given formatting style for the given locale.
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()
Gets the date formatter with the default formatting style for the default FORMAT locale.
This is equivalent to calling getDateInstance(DEFAULT,
Locale.getDefault(Locale.Category.FORMAT)).
Locale.getDefault(java.util.Locale.Category), Locale.Category.FORMAT
public static final DateFormat getDateInstance(int style)
Gets the date formatter with the given formatting style for the default FORMAT locale.
This is equivalent to calling getDateInstance(style,
Locale.getDefault(Locale.Category.FORMAT)).
style - the given formatting style. For example, SHORT for "M/d/yy" in the US locale.Locale.getDefault(java.util.Locale.Category), Locale.Category.FORMAT
public static final DateFormat getDateInstance(int style,
Locale aLocale) Gets the date formatter with the given formatting style for the given locale.
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()
Gets the date/time formatter with the default formatting style for the default FORMAT locale.
This is equivalent to calling getDateTimeInstance(DEFAULT,
DEFAULT, Locale.getDefault(Locale.Category.FORMAT)).
Locale.getDefault(java.util.Locale.Category), Locale.Category.FORMAT
public static final DateFormat getDateTimeInstance(int dateStyle,
int timeStyle) Gets the date/time formatter with the given date and time formatting styles for the default FORMAT locale.
This is equivalent to calling getDateTimeInstance(dateStyle,
timeStyle, Locale.getDefault(Locale.Category.FORMAT)).
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.Locale.getDefault(java.util.Locale.Category), Locale.Category.FORMAT
public static final DateFormat getDateTimeInstance(int dateStyle,
int timeStyle,
Locale aLocale) Gets the date/time formatter with the given formatting styles for the given locale.
dateStyle - the given date formatting style.timeStyle - the given time formatting style.aLocale - the given locale.public static final DateFormat getInstance()
Get a default date/time formatter that uses the SHORT style for both the date and the time.
public static 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 DateFormatProvider implementations. It must contain at least a Locale instance equal to Locale.US.
DateFormat instances are available.public void setCalendar(Calendar newCalendar)
Set the calendar to be used by this date format. Initially, the default calendar for the specified or default locale is used.
Any TimeZone and leniency values that have previously been set are overwritten by newCalendar's values.
newCalendar - the new Calendar to be used by the date formatpublic Calendar getCalendar()
Gets the calendar associated with this date/time formatter.
public void setNumberFormat(NumberFormat newNumberFormat)
Allows you to set the number formatter.
newNumberFormat - the given new NumberFormat.public NumberFormat getNumberFormat()
Gets the number formatter which this date/time formatter uses to format and parse a time.
public void setTimeZone(TimeZone zone)
Sets the time zone for the calendar of this DateFormat object. This method is equivalent to the following call.
getCalendar().setTimeZone(zone)
The TimeZone set by this method is overwritten by a setCalendar call.
The TimeZone set by this method may be overwritten as a result of a call to the parse method.
zone - the given new time zone.public TimeZone getTimeZone()
Gets the time zone. This method is equivalent to the following call.
getCalendar().getTimeZone()
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.
This method is equivalent to the following call.
getCalendar().setLenient(lenient)
This leniency value is overwritten by a call to setCalendar().
lenient - when true, parsing is lenientCalendar.setLenient(boolean)public boolean isLenient()
Tell whether date/time parsing is to be lenient. This method is equivalent to the following call.
getCalendar().isLenient()
true if the calendar is lenient; false otherwise.Calendar.isLenient()public int hashCode()
Overrides hashCode
hashCode in class Object
Object.equals(java.lang.Object), System.identityHashCode(java.lang.Object)
public boolean equals(Object obj)
Overrides equals
equals in class Object
obj - the reference object with which to compare.true if this object is the same as the obj argument; false otherwise.Object.hashCode(), HashMap
public Object clone()
Overrides Cloneable
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