Character class wraps a value of the primitive
char in an object. An object of type
Character contains a single field whose type is
In addition, this class provides several methods for determining a character's category (lowercase letter, digit, etc.) and for converting characters from uppercase to lowercase and vice versa.
Character information is based on the Unicode Standard, version 6.2.0.
The methods and data of class
Character are defined by
the information in the UnicodeData file that is part of the
Unicode Character Database maintained by the Unicode
Consortium. This file specifies various properties including name
and general category for every defined Unicode code point or
The file and its description are available from the Unicode Consortium at:
char data type (and therefore the value that a
Character object encapsulates) are based on the
original Unicode specification, which defined characters as
fixed-width 16-bit entities. The Unicode Standard has since been
changed to allow for characters whose representation requires more
than 16 bits. The range of legal code points is now
U+0000 to U+10FFFF, known as Unicode scalar value.
(Refer to the
definition of the U+n notation in the Unicode
The set of characters from U+0000 to U+FFFF is
sometimes referred to as the Basic Multilingual Plane (BMP).
Characters whose code points are greater
than U+FFFF are called supplementary characters. The Java
platform uses the UTF-16 representation in
char arrays and
StringBuffer classes. In
this representation, supplementary characters are represented as a pair
char values, the first from the high-surrogates
range, (\uD800-\uDBFF), the second from the
low-surrogates range (\uDC00-\uDFFF).
char value, therefore, represents Basic
Multilingual Plane (BMP) code points, including the surrogate
code points, or code units of the UTF-16 encoding. An
int value represents all Unicode code points,
including supplementary code points. The lower (least significant)
21 bits of
int are used to represent Unicode code
points and the upper (most significant) 11 bits must be zero.
Unless otherwise specified, the behavior with respect to
supplementary characters and surrogate
char values is
- The methods that only accept a
charvalue cannot support supplementary characters. They treat
charvalues from the surrogate ranges as undefined characters. For example,
false, even though this specific value if followed by any low-surrogate value in a string would represent a letter.
- The methods that accept an
intvalue support all Unicode characters, including supplementary characters. For example,
truebecause the code point value represents a letter (a CJK ideograph).
In the Java SE API documentation, Unicode code point is
used for character values in the range between U+0000 and U+10FFFF,
and Unicode code unit is used for 16-bit
char values that are code units of the UTF-16
encoding. For more information on Unicode terminology, refer to the
Nested Class Summary
|class||Character.Subset||Instances of this class represent particular subsets of the Unicode character set.|
|class||Character.UnicodeBlock||A family of character subsets representing the character blocks in the Unicode specification.|
|enum||Character.UnicodeScript||A family of character subsets representing the character scripts defined in the Unicode Standard Annex #24: Script Names.|
|int||BYTES||The number of bytes used to represent a
|byte||COMBINING_SPACING_MARK||General category "Mc" in the Unicode specification.|
|byte||CONNECTOR_PUNCTUATION||General category "Pc" in the Unicode specification.|