A NumberFormatFactory is used to register new number formats. The factory should be able to create any of the predefined formats for each locale it supports. When registered, the locales it supports extend or override the locales already supported by ICU.
Note: as of ICU4J 3.2, the default API for NumberFormatFactory uses ULocale instead of Locale. Instead of overriding createFormat(Locale, int), new implementations should override createFactory(ULocale, int). Note that one of these two methods MUST be overridden or else an infinite loop will occur.
@stable ICU 2.6