The Java™ Tutorials
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Locale-Sensitive Services SPI
Trail: Internationalization
Lesson: Setting the Locale

Locale-Sensitive Services SPI

This feature enables the plug-in of locale-dependent data and services. In this way, third parties are able to provide implementations of most locale-sensitive classes in the java.text and java.util packages.

The implementation of SPIs (Service Provider Interface) is based on abstract classes and Java interfaces that are implemented by the service provider. At runtime the Java class loading mechanism is used to dynamically locate and load classes that implement the SPI.

You can use the locale-sensitive services SPI to provide the following locale sensitive implementations:

The corresponding SPIs are contained both in java.text.spi and in java.util.spi packages:

java.util.spi java.text.spi
  • CurrencyNameProvider
  • LocaleServiceProvider
  • TimeZoneNameProvider
  • CalendarDataProvider
  • BreakIteratorProvider
  • CollatorProvider
  • DateFormatProvider
  • DateFormatSymbolsProvider
  • DecimalFormatSymbolsProvider
  • NumberFormatProvider

For example, if you would like to provide a NumberFormat object for a new locale, you have to implement the java.text.spi.NumberFormatProvider class. You need to extend this class and implement its methods:

Locale loc = new Locale("da", "DK");
NumberFormat nf = NumberFormatProvider.getNumberInstance(loc);

These methods first check whether the Java runtime environment supports the requested locale; if so, they use that support. Otherwise, the methods call the getAvailableLocales() methods of installed providers for the appropriate interface to find a provider that supports the requested locale.

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