Not all applications are completely language-independent. You might want to mix the languages spoken by a single application. In this case, rather than changing the current locale, use the locale property of individual MediaType objects to override the current locale.
Normally, the MediaType.locale property is not set, so that the default locale is used at runtime. This makes it very easy to develop an international application that automatically adapts itself to the local requirements (for example, in France, users hear French voice segments and in Britain, users hear UK English voice segments). However, you can override the default locale by specifying a locale for the media objects, for example, to develop a multilingual message.