The syntax for the pattern in the date placeholder is specified by the SimpleDateFormat class. MessageFormat uses a ChoiceFormat object to format this argument. A ChoiceFormat allows you to attach a format to a range of numbers. When the argument value is in a certain range, ChoiceFormat chooses the corresponding format as its result. The syntax for specifying the choices is defined by the ChoiceFormat class and requires that you specify a list of limits and a list of formats.
Curly brackets delimit the placeholder from the rest of the pattern.
The curly brackets and the argument number are required. You can only specify a format if you specify a type because the format depends on the type. Check these classes on how to specify the format pattern in the argument placeholder. Inc. For more information on international resources, see their International Fact Sheet .