Java Reference
In-Depth Information
You want to display numbers, dates, and time in a user-friendly way that conforms to
the language and cultural expectations of your customers.
Solution
The display format for numbers, dates, and time varies across the world and depends
on your user's language and cultural region. Additionally, text collation rules vary by
language. The
java.util.Locale
class represents a specific language and region
of the world. By determining and using your customer's locale, you can apply that loc-
ale to a variety of format classes, which can be used to create user-visible data in ex-
pected forms. Classes that use
Locale
instances to modify their behavior for a partic-
ular language or region are called
locale-sensitive
classes. You can learn more about
how to use
Locale
instances in the
NumberFormat
and
DateFormat
classes. In
this recipe, however, you learn different options for creating these
Locale
instances.
You can create a
Locale
instance in any of the following ways:
•
Use the
Locale.Builder
class to configure and build a
Locale
object.
•
Use the static
Locale.forLanguageTag()
method.
•
Use the
Locale
constructors to create an object.
•
Use preconfigured static
Locale
objects.
The Java
Locale.Builder
class has setter methods that allow you to create loc-
ales that can be transformed into well-formed Best Common Practices (BCP) 47 lan-
guage tags. The “How It Works” section describes the BCP 47 standard in more detail.
For now, you should simply understand that a
Builder
creates
Locale
instances
that comply with that standard.
The following code snippet from the
org.java8recipes.chapter12.recipe12_2.Recipe12_2
class demon-
strates how to create
Builder
and
Locale
instances. You use the created locales in
locale-sensitive classes to produce culturally correct display formats:
private static final long number = 123456789L;
private static final Date now = new Date();
