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:

• BreakIterator objects
• Collator objects
• Language code, Country code, and Variant name for the Locale class
• Time Zone names
• Currency symbols
• DateFormat objects
• DateFormatSymbol objects
• NumberFormat objects
• DecimalFormatSymbols objects

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	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:

• getCurrencyInstance(Locale locale)
• getIntegerInstance(Locale locale)
• getNumberInstance(Locale locale)
• getPercentInstance(Locale locale)

  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.