Java Doc for DateFormat.java in  » 6.0-JDK-Core » text » java » text » Java Source Code / Java DocumentationJava Source Code and Java Documentation

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 Also:   Format
See Also:   NumberFormat
See Also:   SimpleDateFormat
See Also:   java.util.Calendar
See Also:   java.util.GregorianCalendar
See Also:   java.util.TimeZone
version:
   1.63 05/05/07
author:
   Mark Davis, Chen-Lieh Huang, Alan Liu

See the DateFormat.parse(String,ParsePosition) method for more information on date parsing.
Parameters:
  source - A String whose beginning should be parsed.

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.

See the DateFormat.parse(String,ParsePosition) method for more information on date parsing.
Parameters:
  source - A String whose beginning should be parsed. A Date parsed from the string.
exception:
  ParseException - if the beginning of the specified stringcannot be parsed.

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 Also:   java.text.DateFormat.setLenient(boolean)
Parameters:
  source - The date/time string to be parsed
Parameters:
  pos - On input, the position at which to start parsing; onoutput, the position at which parsing terminated, or thestart position if the parse failed. A Date, or null if the input could not be parsed

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 DateFormat.parse(String,ParsePosition) method for more information on date parsing.
Parameters:
  source - A String, part of which should be parsed.
Parameters:
  pos - A ParsePosition object with index and errorindex information as described above. A Date parsed from the string. In case oferror, returns null.
exception:
  NullPointerException - if pos is null.