Java Reference
In-Depth Information
The
Locale
class also defines static
Locale
objects that represent languages:
Because the
DateFormat
class is
abstract
, you can't create objects of the class directly, but you can
obtain
DateFormat
objects by using static methods that are defined in the class, each of which returns a
value of type
DateFormat
. A
DateFormat
object encapsulates a
Locale
and an integer date style. The style
is defined by one of the constants defined in the
DateFormat
class,
SHORT
,
MEDIUM
,
LONG
, or
FULL
that you
saw earlier.
Each
Locale
object has a default style that matches conventions that apply for the country or language it
represents.
You can create
DateFormat
instances that can format a
Date
object as a time, as a date, or as a date and
a time. The static methods that create
DateFormat
objects of various kinds are
getTimeInstance()
that
returns a time formatter,
getDateInstance()
that returns a date formatter, and
getDateTimeInstance()
that returns an object that can format the date and the time. The first two come in three flavors, a no-arg
version where you get a formatter for the default locale and style, a single argument version where you sup-
ply the style for the default locale, and a version that accepts a style argument and a
Locale
argument. The
getDateTimeInstance()
also comes in three versions, the no-arg version that creates a formatter for the
default locale and the default date and time style, a version where you supply two arguments that are the date
style and the time style, and a version that requires three arguments that are the date style, the time style, and
a
Locale
object for the locale.
When you've obtained a
DateFormat
object for the country and the style that you want, and the sort of
data you want to format — the date or the time or both — you're ready to produce a
String
from the
Date
object.
You just pass the
Date
object to the
format()
method for the
DateFormat
object. For example:
Date today = new Date(); // Object for now - today's date
DateFormat fmt = DateFormat.getDateTimeInstance(DateFormat.FULL, // Date style
DateFormat.FULL, // Time style
Locale.US); // Locale
String formatted = fmt.format(today);
The first statement creates a
Date
object that represents the instant in time when the call to the
Date
constructor executes. The second statement creates a
DateFormat
object that can format the date and time
encapsulated by a
Date
object. In this case you specify the formatting style for the data and the time to be
the same, the
FULL
constant in the
DateFormat
class. This provides the most detailed specification of the
date and time. The third argument,
Locale.US
, determines that the formatting should correspond to that re-
quired for the United States. The
Locale
class defines constants for other major countries and languages.
The third statement applies the
format()
method of the
fmt
object to the
Date
object. After executing these
statements, the
String
variable
formatted
contains a full representation of the date and the time when the
Date
object
today
was created.
You can try out some dates and formats in an example.
