Java IO.pdf - Nguyen Dang Binh

Java I/O
The variant is for vendor-specific extensions and is rarely used. The only encodings in Table
16.1 that list variants are the two Norwegian encodings, Norwegian (Bokmål) and Norwegian
(Nynorsk). The Nynorsk encoding has a variant code of "NY". It is permissible to provide
Java more information than it needs. If Java cannot find the variant locale you request, it
provides a locale that only matches the language and country. If it cannot find a locale that
matches the language and the country, it will settle for one that matches the language.
16.3 Number Formats
To print a formatted number in Java, perform these two steps:
1. Format the number as a string.
2. Print the string.
Simple, right? Of course, this is a little like the old recipe for rabbit stew:
1. Catch a rabbit.
2. Boil rabbit in pot with vegetables and spices.
Obviously, step 1 is the tricky part. Fortunately, formatting numbers as strings is somewhat
easier than catching a rabbit. The key class that formats numbers as strings is
java.text.NumberFormat. This is an abstract subclass of java.text.Format. Concrete
subclasses such as java.text.DecimalFormat implement formatting policies for particular
kinds of numbers.
public abstract class NumberFormat extends Format implements Cloneable
The static NumberFormat.getAvailableLocales() method returns a list of all locales
installed that provide number formats. (There may be a few locales installed that only provide
date or text formats, not number formats.)
public static Locale[] getAvailableLocales()
You can request a NumberFormat object for the default locale of the host computer or for one
of the specified locales in Table 16.1 using the static NumberFormat.getInstance() method.
For example:
NumberFormat myFormat = NumberFormat.getInstance();
NumberFormat canadaFormat = NumberFormat.getInstance(Locale.CANADA);
Locale turkey = new Locale("tr", "");
NumberFormat turkishFormat = NumberFormat.getInstance(turkey);
Locale swissItalian = new Locale("it", "CH");
NumberFormat swissItalianFormat = NumberFormat.getInstance(swissItalian);
The number format returned by NumberFormat.getInstance() should do a reasonable job
of formatting most numbers. However, there's at least a theoretical possibility that the
instance returned will format numbers as currencies or percentages. Therefore, it wouldn't
hurt to use NumberFormat.getNumberInstance() instead:
public static final NumberFormat getNumberInstance()
public static NumberFormat getNumberInstance(Locale inLocale)
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