Java in a Nutshell, 5th Edition

Name

NumberFormat

Synopsis

This class formats and parses numbers in a locale-specific way. As an abstract class, it cannot be instantiated directly, but it provides a number of static methods that return instances of a concrete subclass you can use for formatting. The getInstance( ) method returns a NumberFormat object suitable for normal formatting of numbers in either the default locale or in a specified locale. getIntegerInstance( ), getCurrencyInstance( ), and getPercentInstance( ) return NumberFormat objects for formatting numbers that are integers, or represent monetary amounts or percentages. These methods return a NumberFormat suitable for the default locale, or for the specified Locale object. getAvailableLocales( ) returns an array of locales for which NumberFormat objects are available. In Java 1.4 and later, use setCurrency( ) to provide a java.util.Currency object for use when formating monetary values. Note that the NumberFormat class is not intended for the display of very large or very small numbers that require exponential notation, and it may not gracefully handle infinite or NaN (not-a-number) values.

Once you have created a suitable NumberFormat object, you can customize its localeindependent behavior with setMaximumFractionDigits( ), setGroupingUsed( ), and similar set methods. In order to customize the locale-dependent behavior, you can use instanceof to test if the NumberFormat object is an instance of DecimalFormat, and, if so, cast it to that type. The ...