java.lang
Class Character

java.lang.Object
  java.lang.Character

All Implemented Interfaces:

Comparable

public final class Character
extends Object
implements Comparable

Wrapper class for the primitive char data type. In addition, this class allows one to retrieve property information and perform transformations on the 57,707 defined characters in the Unicode Standard, Version 3.0.0. java.lang.Character is designed to be very dynamic, and as such, it retrieves information on the Unicode character set from a separate database, gnu.java.lang.CharData, which can be easily upgraded.

For predicates, boundaries are used to describe the set of characters for which the method will return true. This syntax uses fairly normal regular expression notation. See 5.13 of the Unicode Standard, Version 3.0, for the boundary specification.

See http://www.unicode.org for more information on the Unicode Standard.

Since:

1.0

Field Summary

static byte	COMBINING_SPACING_MARK Mc = Mark, Spacing Combining (Normative).
static byte	CONNECTOR_PUNCTUATION Pc = Punctuation, Connector (Informative).
static byte	CONTROL Cc = Other, Control (Normative).
static byte	CURRENCY_SYMBOL Sc = Symbol, Currency (Informative).
static byte	DASH_PUNCTUATION Pd = Punctuation, Dash (Informative).
static byte	DECIMAL_DIGIT_NUMBER Nd = Number, Decimal Digit (Normative).
static byte	ENCLOSING_MARK Me = Mark, Enclosing (Normative).
static byte	END_PUNCTUATION Pe = Punctuation, Close (Informative).
static byte	FINAL_QUOTE_PUNCTUATION Pf = Punctuation, Final Quote (Informative).
static byte	FORMAT Cf = Other, Format (Normative).
static byte	INITIAL_QUOTE_PUNCTUATION Pi = Punctuation, Initial Quote (Informative).
static byte	LETTER_NUMBER Nl = Number, Letter (Normative).
static byte	LINE_SEPARATOR Zl = Separator, Line (Normative).
static byte	LOWERCASE_LETTER Ll = Letter, Lowercase (Informative).
static byte	MATH_SYMBOL Sm = Symbol, Math (Informative).
static int	MAX_RADIX Largest value allowed for radix arguments in Java.
static char	MAX_VALUE The maximum value the char data type can hold.
static int	MIN_RADIX Smallest value allowed for radix arguments in Java.
static char	MIN_VALUE The minimum value the char data type can hold.
static byte	MODIFIER_LETTER Lm = Letter, Modifier (Informative).
static byte	MODIFIER_SYMBOL Sk = Symbol, Modifier (Informative).
static byte	NON_SPACING_MARK Mn = Mark, Non-Spacing (Normative).
static byte	OTHER_LETTER Lo = Letter, Other (Informative).
static byte	OTHER_NUMBER No = Number, Other (Normative).
static byte	OTHER_PUNCTUATION Po = Punctuation, Other (Informative).
static byte	OTHER_SYMBOL So = Symbol, Other (Informative).
static byte	PARAGRAPH_SEPARATOR Zp = Separator, Paragraph (Normative).
static byte	PRIVATE_USE Co = Other, Private Use (Normative).
static int	SIZE The number of bits needed to represent a char.
static byte	SPACE_SEPARATOR Zs = Separator, Space (Normative).
static byte	START_PUNCTUATION Ps = Punctuation, Open (Informative).
static byte	SURROGATE Cs = Other, Surrogate (Normative).
static byte	TITLECASE_LETTER Lt = Letter, Titlecase (Informative).
static Class	TYPE Class object representing the primitive char data type.
static byte	UNASSIGNED Cn = Other, Not Assigned (Normative).
static byte	UPPERCASE_LETTER Lu = Letter, Uppercase (Informative).

Constructor Summary

Character(char value)
Wraps up a character.

Method Summary

char	charValue() Returns the character which has been wrapped by this class.
int	compareTo(Character anotherCharacter) Compares another Character to this Character, numerically.
int	compareTo(Object o) Compares an object to this Character.
static int	digit(char ch, int radix) Converts a character into a digit of the specified radix.
boolean	equals(Object o) Determines if an object is equal to this object.
static char	forDigit(int digit, int radix) Converts a digit into a character which represents that digit in a specified radix.
int	hashCode() Returns the numerical value (unsigned) of the wrapped character.
static boolean	isDigit(char ch) Determines if a character is a Unicode decimal digit.
static boolean	isLetter(char ch) Determines if a character is a Unicode letter.
static boolean	isLetterOrDigit(char ch) Determines if a character is a Unicode letter or a Unicode digit.
static boolean	isLowerCase(char ch) Determines if a character is a Unicode lowercase letter.
static boolean	isSpace(char ch) Deprecated. Replaced by isWhitespace(char)
static boolean	isSpaceChar(char ch) Determines if a character is a Unicode space character.
static boolean	isUpperCase(char ch) Determines if a character is a Unicode uppercase letter.
static boolean	isWhitespace(char ch) Determines if a character is Java whitespace.
static char	reverseBytes(char val) Reverse the bytes in val.
static char	toLowerCase(char ch) Converts a Unicode character into its lowercase equivalent mapping.
String	toString() Converts the wrapped character into a String.
static String	toString(char ch) Returns a String of length 1 representing the specified character.
static char	toUpperCase(char ch) Converts a Unicode character into its uppercase equivalent mapping.
static Character	valueOf(char val) Returns an Character object wrapping the value.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

MIN_RADIX

public static final int MIN_RADIX

Smallest value allowed for radix arguments in Java. This value is 2.

See Also:

digit(char, int), forDigit(int, int), Integer.toString(int, int), Integer.valueOf(String), Constant Field Values

MAX_RADIX

public static final int MAX_RADIX

Largest value allowed for radix arguments in Java. This value is 36.

See Also:

digit(char, int), forDigit(int, int), Integer.toString(int, int), Integer.valueOf(String), Constant Field Values

MIN_VALUE

public static final char MIN_VALUE

The minimum value the char data type can hold. This value is '\\u0000'.

See Also:

Constant Field Values

MAX_VALUE

public static final char MAX_VALUE

The maximum value the char data type can hold. This value is '\\uFFFF'.

See Also:

Constant Field Values

TYPE

public static final Class TYPE

Class object representing the primitive char data type.

Since:

1.1

SIZE

public static final int SIZE

The number of bits needed to represent a char.

Since:

1.5

See Also:

Constant Field Values

UPPERCASE_LETTER

public static final byte UPPERCASE_LETTER

Lu = Letter, Uppercase (Informative).

Since:

1.1

See Also:

Constant Field Values

LOWERCASE_LETTER

public static final byte LOWERCASE_LETTER

Ll = Letter, Lowercase (Informative).

Since:

1.1

See Also:

Constant Field Values

TITLECASE_LETTER

public static final byte TITLECASE_LETTER

Lt = Letter, Titlecase (Informative).

Since:

1.1

See Also:

Constant Field Values

NON_SPACING_MARK

public static final byte NON_SPACING_MARK

Mn = Mark, Non-Spacing (Normative).

Since:

1.1

See Also:

Constant Field Values

COMBINING_SPACING_MARK

public static final byte COMBINING_SPACING_MARK

Mc = Mark, Spacing Combining (Normative).

Since:

1.1

See Also:

Constant Field Values

ENCLOSING_MARK

public static final byte ENCLOSING_MARK

Me = Mark, Enclosing (Normative).

Since:

1.1

See Also:

Constant Field Values

DECIMAL_DIGIT_NUMBER

public static final byte DECIMAL_DIGIT_NUMBER

Nd = Number, Decimal Digit (Normative).

Since:

1.1

See Also:

Constant Field Values

LETTER_NUMBER

public static final byte LETTER_NUMBER

Nl = Number, Letter (Normative).

Since:

1.1

See Also:

Constant Field Values

OTHER_NUMBER

public static final byte OTHER_NUMBER

No = Number, Other (Normative).

Since:

1.1

See Also:

Constant Field Values

SPACE_SEPARATOR

public static final byte SPACE_SEPARATOR

Zs = Separator, Space (Normative).

Since:

1.1

See Also:

Constant Field Values

LINE_SEPARATOR

public static final byte LINE_SEPARATOR

Zl = Separator, Line (Normative).

Since:

1.1

See Also:

Constant Field Values

PARAGRAPH_SEPARATOR

public static final byte PARAGRAPH_SEPARATOR

Zp = Separator, Paragraph (Normative).

Since:

1.1

See Also:

Constant Field Values

CONTROL

public static final byte CONTROL

Cc = Other, Control (Normative).

Since:

1.1

See Also:

Constant Field Values

FORMAT

public static final byte FORMAT

Cf = Other, Format (Normative).

Since:

1.1

See Also:

Constant Field Values

SURROGATE

public static final byte SURROGATE

Cs = Other, Surrogate (Normative).

Since:

1.1

See Also:

Constant Field Values

PRIVATE_USE

public static final byte PRIVATE_USE

Co = Other, Private Use (Normative).

Since:

1.1

See Also:

Constant Field Values

UNASSIGNED

public static final byte UNASSIGNED

Cn = Other, Not Assigned (Normative).

Since:

1.1

See Also:

Constant Field Values

MODIFIER_LETTER

public static final byte MODIFIER_LETTER

Lm = Letter, Modifier (Informative).

Since:

1.1

See Also:

Constant Field Values

OTHER_LETTER

public static final byte OTHER_LETTER

Lo = Letter, Other (Informative).

Since:

1.1

See Also:

Constant Field Values

CONNECTOR_PUNCTUATION

public static final byte CONNECTOR_PUNCTUATION

Pc = Punctuation, Connector (Informative).

Since:

1.1

See Also:

Constant Field Values

DASH_PUNCTUATION

public static final byte DASH_PUNCTUATION

Pd = Punctuation, Dash (Informative).

Since:

1.1

See Also:

Constant Field Values

START_PUNCTUATION

public static final byte START_PUNCTUATION

Ps = Punctuation, Open (Informative).

Since:

1.1

See Also:

Constant Field Values

END_PUNCTUATION

public static final byte END_PUNCTUATION

Pe = Punctuation, Close (Informative).

Since:

1.1

See Also:

Constant Field Values

INITIAL_QUOTE_PUNCTUATION

public static final byte INITIAL_QUOTE_PUNCTUATION

Pi = Punctuation, Initial Quote (Informative).

Since:

1.4

See Also:

Constant Field Values

FINAL_QUOTE_PUNCTUATION

public static final byte FINAL_QUOTE_PUNCTUATION

Pf = Punctuation, Final Quote (Informative).

Since:

1.4

See Also:

Constant Field Values

OTHER_PUNCTUATION

public static final byte OTHER_PUNCTUATION

Po = Punctuation, Other (Informative).

Since:

1.1

See Also:

Constant Field Values

MATH_SYMBOL

public static final byte MATH_SYMBOL

Sm = Symbol, Math (Informative).

Since:

1.1

See Also:

Constant Field Values

CURRENCY_SYMBOL

public static final byte CURRENCY_SYMBOL

Sc = Symbol, Currency (Informative).

Since:

1.1

See Also:

Constant Field Values

MODIFIER_SYMBOL

public static final byte MODIFIER_SYMBOL

Sk = Symbol, Modifier (Informative).

Since:

1.1

See Also:

Constant Field Values

OTHER_SYMBOL

public static final byte OTHER_SYMBOL

So = Symbol, Other (Informative).

Since:

1.1

See Also:

Constant Field Values

Constructor Detail

Character

public Character(char value)

Wraps up a character.

Parameters:

value - the character to wrap

Method Detail

charValue

public char charValue()

Returns the character which has been wrapped by this class.

Returns:

the character wrapped

hashCode

public int hashCode()

Returns the numerical value (unsigned) of the wrapped character. Range of returned values: 0x0000-0xFFFF.

Overrides:

hashCode in class Object

Returns:

the value of the wrapped character

See Also:

Object.equals(Object), System.identityHashCode(Object)

equals

public boolean equals(Object o)

Determines if an object is equal to this object. This is only true for another Character object wrapping the same value.

Overrides:

equals in class Object

Parameters:

o - object to compare

Returns:

true if o is a Character with the same value

See Also:

Object.hashCode()

toString

public String toString()

Converts the wrapped character into a String.

Overrides:

toString in class Object

Returns:

a String containing one character -- the wrapped character of this instance

See Also:

Object.getClass(), Object.hashCode(), Class.getName(), Integer.toHexString(int)

toString

public static String toString(char ch)

Returns a String of length 1 representing the specified character.

Parameters:

ch - the character to convert

Returns:

a String containing the character

Since:

1.4

isLowerCase

public static boolean isLowerCase(char ch)

Determines if a character is a Unicode lowercase letter. For example, 'a' is lowercase.
lowercase = [Ll]

Parameters:

ch - character to test

Returns:

true if ch is a Unicode lowercase letter, else false

See Also:

isUpperCase(char), #isTitleCase(char), toLowerCase(char), #getType(char)

isUpperCase

public static boolean isUpperCase(char ch)

Determines if a character is a Unicode uppercase letter. For example, 'A' is uppercase.
uppercase = [Lu]

Parameters:

ch - character to test

Returns:

true if ch is a Unicode uppercase letter, else false

See Also:

isLowerCase(char), #isTitleCase(char), toUpperCase(char), #getType(char)

isDigit

public static boolean isDigit(char ch)

Determines if a character is a Unicode decimal digit. For example, '0' is a digit.
Unicode decimal digit = [Nd]

Parameters:

ch - character to test

Returns:

true if ch is a Unicode decimal digit, else false

See Also:

digit(char, int), forDigit(int, int), #getType(char)

isLetter

public static boolean isLetter(char ch)

Determines if a character is a Unicode letter. Not all letters have case, so this may return true when isLowerCase and isUpperCase return false.
letter = [Lu]|[Ll]|[Lt]|[Lm]|[Lo]

Parameters:

ch - character to test

Returns:

true if ch is a Unicode letter, else false

See Also:

isDigit(char), #isJavaIdentifierStart(char), #isJavaLetter(char), #isJavaLetterOrDigit(char), isLetterOrDigit(char), isLowerCase(char), #isTitleCase(char), #isUnicodeIdentifierStart(char), isUpperCase(char)

isLetterOrDigit

public static boolean isLetterOrDigit(char ch)

Determines if a character is a Unicode letter or a Unicode digit. This is the combination of isLetter and isDigit.
letter or digit = [Lu]|[Ll]|[Lt]|[Lm]|[Lo]|[Nd]

Parameters:

ch - character to test

Returns:

true if ch is a Unicode letter or a Unicode digit, else false

See Also:

isDigit(char), #isJavaIdentifierPart(char), #isJavaLetter(char), #isJavaLetterOrDigit(char), isLetter(char), #isUnicodeIdentifierPart(char)

toLowerCase

public static char toLowerCase(char ch)

Converts a Unicode character into its lowercase equivalent mapping. If a mapping does not exist, then the character passed is returned. Note that isLowerCase(toLowerCase(ch)) does not always return true.

Parameters:

ch - character to convert to lowercase

Returns:

lowercase mapping of ch, or ch if lowercase mapping does not exist

See Also:

isLowerCase(char), isUpperCase(char), #toTitleCase(char), toUpperCase(char)

toUpperCase

public static char toUpperCase(char ch)

Converts a Unicode character into its uppercase equivalent mapping. If a mapping does not exist, then the character passed is returned. Note that isUpperCase(toUpperCase(ch)) does not always return true.

Parameters:

ch - character to convert to uppercase

Returns:

uppercase mapping of ch, or ch if uppercase mapping does not exist

See Also:

isLowerCase(char), isUpperCase(char), toLowerCase(char), #toTitleCase(char)

digit

public static int digit(char ch,
                        int radix)

Converts a character into a digit of the specified radix. If the radix exceeds MIN_RADIX or MAX_RADIX, or if the result of getNumericValue(ch) exceeds the radix, or if ch is not a decimal digit or in the case insensitive set of 'a'-'z', the result is -1.
character argument boundary = [Nd]|U+0041-U+005A|U+0061-U+007A |U+FF21-U+FF3A|U+FF41-U+FF5A

Parameters:

ch - character to convert into a digit

radix - radix in which ch is a digit

Returns:

digit which ch represents in radix, or -1 not a valid digit

See Also:

MIN_RADIX, MAX_RADIX, forDigit(int, int), isDigit(char), #getNumericValue(char)

isSpace

public static boolean isSpace(char ch)

Deprecated. Replaced by isWhitespace(char)

Determines if a character is a ISO-LATIN-1 space. This is only the five characters '\t', '\n', '\f', '\r', and ' '.
Java space = U+0020|U+0009|U+000A|U+000C|U+000D

Parameters:

ch - character to test

Returns:

true if ch is a space, else false

See Also:

isSpaceChar(char), isWhitespace(char)

isSpaceChar

public static boolean isSpaceChar(char ch)

Determines if a character is a Unicode space character. This includes SPACE_SEPARATOR, LINE_SEPARATOR, and PARAGRAPH_SEPARATOR.
Unicode space = [Zs]|[Zp]|[Zl]

Parameters:

ch - character to test

Returns:

true if ch is a Unicode space, else false

Since:

1.1

See Also:

isWhitespace(char)

isWhitespace

public static boolean isWhitespace(char ch)

Determines if a character is Java whitespace. This includes Unicode space characters (SPACE_SEPARATOR, LINE_SEPARATOR, and PARAGRAPH_SEPARATOR) except the non-breaking spaces (' ', '?', and '?'); and these characters: ' ', ' ', '', ' ', ' ', '', '', '', and ''.
Java whitespace = ([Zs] not Nb)|[Zl]|[Zp]|U+0009-U+000D|U+001C-U+001F

Parameters:

ch - character to test

Returns:

true if ch is Java whitespace, else false

Since:

1.1

See Also:

isSpaceChar(char)

forDigit

public static char forDigit(int digit,
                            int radix)

Converts a digit into a character which represents that digit in a specified radix. If the radix exceeds MIN_RADIX or MAX_RADIX, or the digit exceeds the radix, then the null character '\0' is returned. Otherwise the return value is in '0'-'9' and 'a'-'z'.
return value boundary = U+0030-U+0039|U+0061-U+007A

Parameters:

digit - digit to be converted into a character

radix - radix of digit

Returns:

character representing digit in radix, or '\0'

See Also:

MIN_RADIX, MAX_RADIX, digit(char, int)

compareTo

public int compareTo(Character anotherCharacter)

Compares another Character to this Character, numerically.

Parameters:

anotherCharacter - Character to compare with this Character

Returns:

a negative integer if this Character is less than anotherCharacter, zero if this Character is equal, and a positive integer if this Character is greater

Throws:

NullPointerException - if anotherCharacter is null

Since:

1.2

compareTo

public int compareTo(Object o)

Compares an object to this Character. Assuming the object is a Character object, this method performs the same comparison as compareTo(Character).

Specified by:

compareTo in interface Comparable

Parameters:

o - object to compare

Returns:

the comparison value

Throws:

ClassCastException - if o is not a Character object

NullPointerException - if o is null

Since:

1.2

See Also:

compareTo(Character)

valueOf

public static Character valueOf(char val)

Returns an Character object wrapping the value. In contrast to the Character constructor, this method will cache some values. It is used by boxing conversion.

Parameters:

val - the value to wrap

Returns:

the Character

Since:

1.5

reverseBytes

public static char reverseBytes(char val)

Reverse the bytes in val.

Since:

1.5