These classes are capable of formatting dates, numbers, and messages, parsing; searching and sorting strings; and iterating over characters, words, sentences, and line breaks. This package contains three main groups of classes and interfaces:
Dates and numbers are represented internally in a locale-independent way. For example, dates are kept as milliseconds since January 1, 1970, 00:00:00 UCT. When these objects are printed or displayed, they must be converted to localized strings. The locale-specific parts of a date string, such as the time zone string, are separately imported from a locale-specific resource bundle.
The format() method converts the Date
object from -604656780000 milliseconds to the form "Tuesday, November
3, 1997 9:47am CST" for the U. S. English locale. The figure shows how the
format() method of subclasses of Format
enable instances of Number, Date,
String, and other objects to be formatted to
locale-specific strings.
Conversely, the parseObject() method (and
parse() method in subclasses) perform the reverse
operation of parsing localized strings and converting them to
Number, Date, and
String objects. The figure
shows how the parse() method is complementary to
format(). Any String formatted by
format() is guaranteed to be parseable by
parseObject().
Java provides six subclasses of Format for formatting
dates, numbers, and messages: DateFormat,
SimpleDateFormat, NumberFormat,
DecimalFormat, ChoiceFormat, and
MessageFormat.
Collator class and its subclass
RuleBasedCollator perform locale-sensitive string
comparison. You use these classes to build searching and alphabetical
sorting routines for natural language text. They can distinguish
characters based on the base character, accent marks, and
uppercase/lowercase properties.
Collator is an abstract base class. Subclasses
implement specific collation strategies. One subclass,
RuleBasedCollator, is currently provided and is
applicable to a wide set of languages. Other subclasses may be created
to handle more specialized
needs. CollationElementIterator provides an iterator for
stepping through each character of a locale-specific string according
to the rules of a specific Collator
object. CollationKey enables fast sorting of strings by
representing a string as a sort key under the rules of a specific
Collator object.
char and Character
represent Unicode characters, sometimes Unicode characters combine to
form a more complex character that has its own semantic value, a
user character. The BreakIterator class makes it
possible to iterate over these user characters. A break iterator can
find the location of character, word, or sentence boundaries or
potential line-break boundaries. This makes it possible for a program
to properly select characters for text operations such as highlighting
a character, cutting a word, moving to the next sentence, or
word-wrapping at a line ending. These operations are performed in a
locale-sensitive manner, meaning that they honor the boundaries of
text for a particular locale.
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Locale-Sensitive Classes NumberFormat DecimalFormat DecimalFormatSymbols MessageFormat DateFormat SimpleDateFormat DateFormatSymbols Collator RuleBasedCollator CollationElementIterator CollationKey BreakIterator |
Locale-Independent Classes Format ChoiceFormat FieldPosition ParsePosition ParseException StringCharacterIterator CharacterIterator |