JavaTM 2 Platform
Std. Ed. v1.4.2

java.lang
Class Character

java.lang.Object
  extended byjava.lang.Character
All Implemented Interfaces:
Comparable, Serializable

public final class Character
extends Object
implements Serializable, Comparable

The Character class wraps a value of the primitive type char in an object. An object of type Character contains a single field whose type is char.

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 3.0.

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 character range.

The file and its description are available from the Unicode Consortium at:

Since:
1.0
See Also:
Serialized Form

Nested Class Summary
static class Character.Subset
          Instances of this class represent particular subsets of the Unicode character set.
static class Character.UnicodeBlock
          A family of character subsets representing the character blocks in the Unicode specification.
 
Field Summary
static byte COMBINING_SPACING_MARK
          General category "Mc" in the Unicode specification.
static byte CONNECTOR_PUNCTUATION
          General category "Pc" in the Unicode specification.
static byte CONTROL
          General category "Cc" in the Unicode specification.
static byte CURRENCY_SYMBOL
          General category "Sc" in the Unicode specification.
static byte DASH_PUNCTUATION
          General category "Pd" in the Unicode specification.
static byte DECIMAL_DIGIT_NUMBER
          General category "Nd" in the Unicode specification.
static byte DIRECTIONALITY_ARABIC_NUMBER
          Weak bidirectional character type "AN" in the Unicode specification.
static byte DIRECTIONALITY_BOUNDARY_NEUTRAL
          Weak bidirectional character type "BN" in the Unicode specification.
static byte DIRECTIONALITY_COMMON_NUMBER_SEPARATOR
          Weak bidirectional character type "CS" in the Unicode specification.
static byte DIRECTIONALITY_EUROPEAN_NUMBER
          Weak bidirectional character type "EN" in the Unicode specification.
static byte DIRECTIONALITY_EUROPEAN_NUMBER_SEPARATOR
          Weak bidirectional character type "ES" in the Unicode specification.
static byte DIRECTIONALITY_EUROPEAN_NUMBER_TERMINATOR
          Weak bidirectional character type "ET" in the Unicode specification.
static byte DIRECTIONALITY_LEFT_TO_RIGHT
          Strong bidirectional character type "L" in the Unicode specification.
static byte DIRECTIONALITY_LEFT_TO_RIGHT_EMBEDDING
          Strong bidirectional character type "LRE" in the Unicode specification.
static byte DIRECTIONALITY_LEFT_TO_RIGHT_OVERRIDE
          Strong bidirectional character type "LRO" in the Unicode specification.
static byte DIRECTIONALITY_NONSPACING_MARK
          Weak bidirectional character type "NSM" in the Unicode specification.
static byte DIRECTIONALITY_OTHER_NEUTRALS
          Neutral bidirectional character type "ON" in the Unicode specification.
static byte DIRECTIONALITY_PARAGRAPH_SEPARATOR
          Neutral bidirectional character type "B" in the Unicode specification.
static byte DIRECTIONALITY_POP_DIRECTIONAL_FORMAT
          Weak bidirectional character type "PDF" in the Unicode specification.
static byte DIRECTIONALITY_RIGHT_TO_LEFT
          Strong bidirectional character type "R" in the Unicode specification.
static byte DIRECTIONALITY_RIGHT_TO_LEFT_ARABIC
          Strong bidirectional character type "AL" in the Unicode specification.
static byte DIRECTIONALITY_RIGHT_TO_LEFT_EMBEDDING
          Strong bidirectional character type "RLE" in the Unicode specification.
static byte DIRECTIONALITY_RIGHT_TO_LEFT_OVERRIDE
          Strong bidirectional character type "RLO" in the Unicode specification.
static byte DIRECTIONALITY_SEGMENT_SEPARATOR
          Neutral bidirectional character type "S" in the Unicode specification.
static byte DIRECTIONALITY_UNDEFINED
          Undefined bidirectional character type.
static byte DIRECTIONALITY_WHITESPACE
          Neutral bidirectional character type "WS" in the Unicode specification.
static byte ENCLOSING_MARK
          General category "Me" in the Unicode specification.
static byte END_PUNCTUATION
          General category "Pe" in the Unicode specification.
static byte FINAL_QUOTE_PUNCTUATION
          General category "Pf" in the Unicode specification.
static byte FORMAT
          General category "Cf" in the Unicode specification.
static byte INITIAL_QUOTE_PUNCTUATION
          General category "Pi" in the Unicode specification.
static byte LETTER_NUMBER
          General category "Nl" in the Unicode specification.
static byte LINE_SEPARATOR
          General category "Zl" in the Unicode specification.
static byte LOWERCASE_LETTER
          General category "Ll" in the Unicode specification.
static byte MATH_SYMBOL
          General category "Sm" in the Unicode specification.
static int MAX_RADIX
          The maximum radix available for conversion to and from strings.
static char MAX_VALUE
          The constant value of this field is the largest value of type char, '\uFFFF'.
static int MIN_RADIX
          The minimum radix available for conversion to and from strings.
static char MIN_VALUE
          The constant value of this field is the smallest value of type char, '\u0000'.
static byte MODIFIER_LETTER
          General category "Lm" in the Unicode specification.
static byte MODIFIER_SYMBOL
          General category "Sk" in the Unicode specification.
static byte NON_SPACING_MARK
          General category "Mn" in the Unicode specification.
static byte OTHER_LETTER
          General category "Lo" in the Unicode specification.
static byte OTHER_NUMBER
          General category "No" in the Unicode specification.
static byte OTHER_PUNCTUATION
          General category "Po" in the Unicode specification.
static byte OTHER_SYMBOL
          General category "So" in the Unicode specification.
static byte PARAGRAPH_SEPARATOR
          General category "Zp" in the Unicode specification.
static byte PRIVATE_USE
          General category "Co" in the Unicode specification.
static byte SPACE_SEPARATOR
          General category "Zs" in the Unicode specification.
static byte START_PUNCTUATION
          General category "Ps" in the Unicode specification.
static byte SURROGATE
          General category "Cs" in the Unicode specification.
static byte TITLECASE_LETTER
          General category "Lt" in the Unicode specification.
static Class TYPE
          The Class instance representing the primitive type char.
static byte UNASSIGNED
          General category "Cn" in the Unicode specification.
static byte UPPERCASE_LETTER
          General category "Lu" in the Unicode specification.
 
Constructor Summary
Character(char value)
          Constructs a newly allocated Character object that represents the specified char value.
 
Method Summary
 char charValue()
          Returns the value of this Character object.
 int compareTo(Character anotherCharacter)
          Compares two Character objects numerically.
 int compareTo(Object o)
          Compares this Character object to another object.
static int digit(char ch, int radix)
          Returns the numeric value of the character ch in the specified radix.
 boolean equals(Object obj)
          Compares this object against the specified object.
static char forDigit(int digit, int radix)
          Determines the character representation for a specific digit in the specified radix.
static byte getDirectionality(char ch)
          Returns the Unicode directionality property for the given character.
static int getNumericValue(char ch)
          Returns the int value that the specified Unicode character represents.
static int getType(char ch)
          Returns a value indicating a character's general category.
 int hashCode()
          Returns a hash code for this Character.
static boolean isDefined(char ch)
          Determines if a character is defined in Unicode.
static boolean isDigit(char ch)
          Determines if the specified character is a digit.
static boolean isIdentifierIgnorable(char ch)
          Determines if the specified character should be regarded as an ignorable character in a Java identifier or a Unicode identifier.
static boolean isISOControl(char ch)
          Determines if the specified character is an ISO control character.
static boolean isJavaIdentifierPart(char ch)
          Determines if the specified character may be part of a Java identifier as other than the first character.
static boolean isJavaIdentifierStart(char ch)
          Determines if the specified character is permissible as the first character in a Java identifier.
static boolean isJavaLetter(char ch)
          Deprecated. Replaced by isJavaIdentifierStart(char).
static boolean isJavaLetterOrDigit(char ch)
          Deprecated. Replaced by isJavaIdentifierPart(char).
static boolean isLetter(char ch)
          Determines if the specified character is a letter.
static boolean isLetterOrDigit(char ch)
          Determines if the specified character is a letter or digit.
static boolean isLowerCase(char ch)
          Determines if the specified character is a lowercase character.
static boolean isMirrored(char ch)
          Determines whether the character is mirrored according to the Unicode specification.
static boolean isSpace(char ch)
          Deprecated. Replaced by isWhitespace(char).
static boolean isSpaceChar(char ch)
          Determines if the specified character is a Unicode space character.
static boolean isTitleCase(char ch)
          Determines if the specified character is a titlecase character.
static boolean isUnicodeIdentifierPart(char ch)
          Determines if the specified character may be part of a Unicode identifier as other than the first character.
static boolean isUnicodeIdentifierStart(char ch)
          Determines if the specified character is permissible as the first character in a Unicode identifier.
static boolean isUpperCase(char ch)
          Determines if the specified character is an uppercase character.
static boolean isWhitespace(char ch)
          Determines if the specified character is white space according to Java.
static char toLowerCase(char ch)
          Converts the character argument to lowercase using case mapping information from the UnicodeData file.
 String toString()
          Returns a String object representing this Character's value.
static String toString(char c)
          Returns a String object representing the specified char.
static char toTitleCase(char ch)
          Converts the character argument to titlecase using case mapping information from the UnicodeData file.
static char toUpperCase(char ch)
          Converts the character argument to uppercase using case mapping information from the UnicodeData file.
 
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
The minimum radix available for conversion to and from strings. The constant value of this field is the smallest value permitted for the radix argument in radix-conversion methods such as the digit method, the forDigit method, and the toString method of class Integer.

See Also:
digit(char, int), forDigit(int, int), Integer.toString(int, int), Integer.valueOf(java.lang.String), Constant Field Values

MAX_RADIX

public static final int MAX_RADIX
The maximum radix available for conversion to and from strings. The constant value of this field is the largest value permitted for the radix argument in radix-conversion methods such as the digit method, the forDigit method, and the toString method of class Integer.

See Also:
digit(char, int), forDigit(int, int), Integer.toString(int, int), Integer.valueOf(java.lang.String), Constant Field Values

MIN_VALUE

public static final char MIN_VALUE
The constant value of this field is the smallest value of type char, '\u0000'.

Since:
1.0.2
See Also:
Constant Field Values

MAX_VALUE

public static final char MAX_VALUE
The constant value of this field is the largest value of type char, '\uFFFF'.

Since:
1.0.2
See Also:
Constant Field Values

TYPE

public static final Class TYPE
The Class instance representing the primitive type char.

Since:
1.1

UNASSIGNED

public static final byte UNASSIGNED
General category "Cn" in the Unicode specification.

Since:
1.1
See Also:
Constant Field Values

UPPERCASE_LETTER

public static final byte UPPERCASE_LETTER
General category "Lu" in the Unicode specification.

Since:
1.1
See Also:
Constant Field Values

LOWERCASE_LETTER

public static final byte LOWERCASE_LETTER
General category "Ll" in the Unicode specification.

Since:
1.1
See Also:
Constant Field Values

TITLECASE_LETTER

public static final byte TITLECASE_LETTER
General category "Lt" in the Unicode specification.

Since:
1.1
See Also:
Constant Field Values

MODIFIER_LETTER

public static final byte MODIFIER_LETTER
General category "Lm" in the Unicode specification.

Since:
1.1
See Also:
Constant Field Values

OTHER_LETTER

public static final byte OTHER_LETTER
General category "Lo" in the Unicode specification.

Since:
1.1
See Also:
Constant Field Values

NON_SPACING_MARK

public static final byte NON_SPACING_MARK
General category "Mn" in the Unicode specification.

Since:
1.1
See Also:
Constant Field Values

ENCLOSING_MARK

public static final byte ENCLOSING_MARK
General category "Me" in the Unicode specification.

Since:
1.1
See Also:
Constant Field Values

COMBINING_SPACING_MARK

public static final byte COMBINING_SPACING_MARK
General category "Mc" in the Unicode specification.

Since:
1.1
See Also:
Constant Field Values

DECIMAL_DIGIT_NUMBER

public static final byte DECIMAL_DIGIT_NUMBER
General category "Nd" in the Unicode specification.

Since:
1.1
See Also:
Constant Field Values

LETTER_NUMBER

public static final byte LETTER_NUMBER
General category "Nl" in the Unicode specification.

Since:
1.1
See Also:
Constant Field Values

OTHER_NUMBER

public static final byte OTHER_NUMBER
General category "No" in the Unicode specification.

Since:
1.1
See Also:
Constant Field Values

SPACE_SEPARATOR

public static final byte SPACE_SEPARATOR
General category "Zs" in the Unicode specification.

Since:
1.1
See Also:
Constant Field Values

LINE_SEPARATOR

public static final byte LINE_SEPARATOR
General category "Zl" in the Unicode specification.

Since:
1.1
See Also:
Constant Field Values

PARAGRAPH_SEPARATOR

public static final byte PARAGRAPH_SEPARATOR
General category "Zp" in the Unicode specification.

Since:
1.1
See Also:
Constant Field Values

CONTROL

public static final byte CONTROL
General category "Cc" in the Unicode specification.

Since:
1.1
See Also:
Constant Field Values

FORMAT

public static final byte FORMAT
General category "Cf" in the Unicode specification.

Since:
1.1
See Also:
Constant Field Values

PRIVATE_USE

public static final byte PRIVATE_USE
General category "Co" in the Unicode specification.

Since:
1.1
See Also:
Constant Field Values

SURROGATE

public static final byte SURROGATE
General category "Cs" in the Unicode specification.

Since:
1.1
See Also:
Constant Field Values

DASH_PUNCTUATION

public static final byte DASH_PUNCTUATION
General category "Pd" in the Unicode specification.

Since:
1.1
See Also:
Constant Field Values

START_PUNCTUATION

public static final byte START_PUNCTUATION
General category "Ps" in the Unicode specification.

Since:
1.1
See Also:
Constant Field Values

END_PUNCTUATION

public static final byte END_PUNCTUATION
General category "Pe" in the Unicode specification.

Since:
1.1
See Also:
Constant Field Values

CONNECTOR_PUNCTUATION

public static final byte CONNECTOR_PUNCTUATION
General category "Pc" in the Unicode specification.

Since:
1.1
See Also:
Constant Field Values

OTHER_PUNCTUATION

public static final byte OTHER_PUNCTUATION
General category "Po" in the Unicode specification.

Since:
1.1
See Also:
Constant Field Values

MATH_SYMBOL

public static final byte MATH_SYMBOL
General category "Sm" in the Unicode specification.

Since:
1.1
See Also:
Constant Field Values

CURRENCY_SYMBOL

public static final byte CURRENCY_SYMBOL
General category "Sc" in the Unicode specification.

Since:
1.1
See Also:
Constant Field Values

MODIFIER_SYMBOL

public static final byte MODIFIER_SYMBOL
General category "Sk" in the Unicode specification.

Since:
1.1
See Also:
Constant Field Values

OTHER_SYMBOL

public static final byte OTHER_SYMBOL
General category "So" in the Unicode specification.

Since:
1.1
See Also:
Constant Field Values

INITIAL_QUOTE_PUNCTUATION

public static final byte INITIAL_QUOTE_PUNCTUATION
General category "Pi" in the Unicode specification.

Since:
1.4
See Also:
Constant Field Values

FINAL_QUOTE_PUNCTUATION

public static final byte FINAL_QUOTE_PUNCTUATION
General category "Pf" in the Unicode specification.

Since:
1.4
See Also:
Constant Field Values

DIRECTIONALITY_UNDEFINED

public static final byte DIRECTIONALITY_UNDEFINED
Undefined bidirectional character type. Undefined char values have undefined directionality in the Unicode specification.

Since:
1.4
See Also:
Constant Field Values

DIRECTIONALITY_LEFT_TO_RIGHT

public static final byte DIRECTIONALITY_LEFT_TO_RIGHT
Strong bidirectional character type "L" in the Unicode specification.

Since:
1.4
See Also:
Constant Field Values

DIRECTIONALITY_RIGHT_TO_LEFT

public static final byte DIRECTIONALITY_RIGHT_TO_LEFT
Strong bidirectional character type "R" in the Unicode specification.

Since:
1.4
See Also:
Constant Field Values

DIRECTIONALITY_RIGHT_TO_LEFT_ARABIC

public static final byte DIRECTIONALITY_RIGHT_TO_LEFT_ARABIC
Strong bidirectional character type "AL" in the Unicode specification.

Since:
1.4
See Also:
Constant Field Values

DIRECTIONALITY_EUROPEAN_NUMBER

public static final byte DIRECTIONALITY_EUROPEAN_NUMBER
Weak bidirectional character type "EN" in the Unicode specification.

Since:
1.4
See Also:
Constant Field Values

DIRECTIONALITY_EUROPEAN_NUMBER_SEPARATOR

public static final byte DIRECTIONALITY_EUROPEAN_NUMBER_SEPARATOR
Weak bidirectional character type "ES" in the Unicode specification.

Since:
1.4
See Also:
Constant Field Values

DIRECTIONALITY_EUROPEAN_NUMBER_TERMINATOR

public static final byte DIRECTIONALITY_EUROPEAN_NUMBER_TERMINATOR
Weak bidirectional character type "ET" in the Unicode specification.

Since:
1.4
See Also:
Constant Field Values

DIRECTIONALITY_ARABIC_NUMBER

public static final byte DIRECTIONALITY_ARABIC_NUMBER
Weak bidirectional character type "AN" in the Unicode specification.

Since:
1.4
See Also:
Constant Field Values

DIRECTIONALITY_COMMON_NUMBER_SEPARATOR

public static final byte DIRECTIONALITY_COMMON_NUMBER_SEPARATOR
Weak bidirectional character type "CS" in the Unicode specification.

Since:
1.4
See Also:
Constant Field Values

DIRECTIONALITY_NONSPACING_MARK

public static final byte DIRECTIONALITY_NONSPACING_MARK
Weak bidirectional character type "NSM" in the Unicode specification.

Since:
1.4
See Also:
Constant Field Values

DIRECTIONALITY_BOUNDARY_NEUTRAL

public static final byte DIRECTIONALITY_BOUNDARY_NEUTRAL
Weak bidirectional character type "BN" in the Unicode specification.

Since:
1.4
See Also:
Constant Field Values

DIRECTIONALITY_PARAGRAPH_SEPARATOR

public static final byte DIRECTIONALITY_PARAGRAPH_SEPARATOR
Neutral bidirectional character type "B" in the Unicode specification.

Since:
1.4
See Also:
Constant Field Values

DIRECTIONALITY_SEGMENT_SEPARATOR

public static final byte DIRECTIONALITY_SEGMENT_SEPARATOR
Neutral bidirectional character type "S" in the Unicode specification.

Since:
1.4
See Also:
Constant Field Values

DIRECTIONALITY_WHITESPACE

public static final byte DIRECTIONALITY_WHITESPACE
Neutral bidirectional character type "WS" in the Unicode specification.

Since:
1.4
See Also:
Constant Field Values

DIRECTIONALITY_OTHER_NEUTRALS

public static final byte DIRECTIONALITY_OTHER_NEUTRALS
Neutral bidirectional character type "ON" in the Unicode specification.

Since:
1.4
See Also:
Constant Field Values

DIRECTIONALITY_LEFT_TO_RIGHT_EMBEDDING

public static final byte DIRECTIONALITY_LEFT_TO_RIGHT_EMBEDDING
Strong bidirectional character type "LRE" in the Unicode specification.

Since:
1.4
See Also:
Constant Field Values

DIRECTIONALITY_LEFT_TO_RIGHT_OVERRIDE

public static final byte DIRECTIONALITY_LEFT_TO_RIGHT_OVERRIDE
Strong bidirectional character type "LRO" in the Unicode specification.

Since:
1.4
See Also:
Constant Field Values

DIRECTIONALITY_RIGHT_TO_LEFT_EMBEDDING

public static final byte DIRECTIONALITY_RIGHT_TO_LEFT_EMBEDDING
Strong bidirectional character type "RLE" in the Unicode specification.

Since:
1.4
See Also:
Constant Field Values

DIRECTIONALITY_RIGHT_TO_LEFT_OVERRIDE

public static final byte DIRECTIONALITY_RIGHT_TO_LEFT_OVERRIDE
Strong bidirectional character type "RLO" in the Unicode specification.

Since:
1.4
See Also:
Constant Field Values

DIRECTIONALITY_POP_DIRECTIONAL_FORMAT

public static final byte DIRECTIONALITY_POP_DIRECTIONAL_FORMAT
Weak bidirectional character type "PDF" in the Unicode specification.

Since:
1.4
See Also:
Constant Field Values
Constructor Detail

Character

public Character(char value)
Constructs a newly allocated Character object that represents the specified char value.

Parameters:
value - the value to be represented by the Character object.
Method Detail

charValue

public char charValue()
Returns the value of this Character object.

Returns:
the primitive char value represented by this object.

hashCode

public int hashCode()
Returns a hash code for this Character.

Overrides:
hashCode in class Object
Returns:
a hash code value for this object.
See Also:
Object.equals(java.lang.Object), Hashtable

equals

public boolean equals(Object obj)
Compares this object against the specified object. The result is true if and only if the argument is not null and is a Character object that represents the same char value as this object.

Overrides:
equals in class Object
Parameters:
obj - the object to compare with.
Returns:
true if the objects are the same; false otherwise.
See Also:
Object.hashCode(), Hashtable

toString

public String toString()
Returns a String object representing this Character's value. The result is a string of length 1 whose sole component is the primitive char value represented by this Character object.

Overrides:
toString in class Object
Returns:
a string representation of this object.

toString

public static String toString(char c)
Returns a String object representing the specified char. The result is a string of length 1 consisting solely of the specified char.

Parameters:
c - the char to be converted
Returns:
the string representation of the specified char
Since:
1.4

isLowerCase

public static boolean isLowerCase(char ch)
Determines if the specified character is a lowercase character.

A character is lowercase if its general category type, provided by Character.getType(ch), is LOWERCASE_LETTER.

The following are examples of lowercase characters:

 a b c d e f g h i j k l m n o p q r s t u v w x y z
 '\u00DF' '\u00E0' '\u00E1' '\u00E2' '\u00E3' '\u00E4' '\u00E5' '\u00E6' 
 '\u00E7' '\u00E8' '\u00E9' '\u00EA' '\u00EB' '\u00EC' '\u00ED' '\u00EE'
 '\u00EF' '\u00F0' '\u00F1' '\u00F2' '\u00F3' '\u00F4' '\u00F5' '\u00F6'
 '\u00F8' '\u00F9' '\u00FA' '\u00FB' '\u00FC' '\u00FD' '\u00FE' '\u00FF'
 

Many other Unicode characters are lowercase too.

Parameters:
ch - the character to be tested.
Returns:
true if the character is lowercase; false otherwise.
See Also:
isLowerCase(char), isTitleCase(char), toLowerCase(char), getType(char)

isUpperCase

public static boolean isUpperCase(char ch)
Determines if the specified character is an uppercase character.

A character is uppercase if its general category type, provided by Character.getType(ch), is UPPERCASE_LETTER.

The following are examples of uppercase characters:

 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
 '\u00C0' '\u00C1' '\u00C2' '\u00C3' '\u00C4' '\u00C5' '\u00C6' '\u00C7'
 '\u00C8' '\u00C9' '\u00CA' '\u00CB' '\u00CC' '\u00CD' '\u00CE' '\u00CF'
 '\u00D0' '\u00D1' '\u00D2' '\u00D3' '\u00D4' '\u00D5' '\u00D6' '\u00D8'
 '\u00D9' '\u00DA' '\u00DB' '\u00DC' '\u00DD' '\u00DE'
 

Many other Unicode characters are uppercase too.

Parameters:
ch - the character to be tested.
Returns:
true if the character is uppercase; false otherwise.
Since:
1.0
See Also:
isLowerCase(char), isTitleCase(char), toUpperCase(char), getType(char)

isTitleCase

public static boolean isTitleCase(char ch)
Determines if the specified character is a titlecase character.

A character is a titlecase character if its general category type, provided by Character.getType(ch), is TITLECASE_LETTER.

Some characters look like pairs of Latin letters. For example, there is an uppercase letter that looks like "LJ" and has a corresponding lowercase letter that looks like "lj". A third form, which looks like "Lj", is the appropriate form to use when rendering a word in lowercase with initial capitals, as for a book title.

These are some of the Unicode characters for which this method returns true:

Many other Unicode characters are titlecase too.

Parameters:
ch - the character to be tested.
Returns:
true if the character is titlecase; false otherwise.
Since:
1.0.2
See Also:
isLowerCase(char), isUpperCase(char), toTitleCase(char), getType(char)

isDigit

public static boolean isDigit(char ch)
Determines if the specified character is a digit.

A character is a digit if its general category type, provided by Character.getType(ch), is DECIMAL_DIGIT_NUMBER.

Some Unicode character ranges that contain digits:

Many other character ranges contain digits as well.

Parameters:
ch - the character to be tested.
Returns:
true if the character is a digit; false otherwise.
See Also:
digit(char, int), forDigit(int, int), getType(char)

isDefined

public static boolean isDefined(char ch)
Determines if a character is defined in Unicode.

A character is defined if at least one of the following is true:

Parameters:
ch - the character to be tested
Returns:
true if the character has a defined meaning in Unicode; false otherwise.
Since:
1.0.2
See Also:
isDigit(char), isLetter(char), isLetterOrDigit(char), isLowerCase(char), isTitleCase(char), isUpperCase(char)

isLetter

public static boolean isLetter(char ch)
Determines if the specified character is a letter.

A character is considered to be a letter if its general category type, provided by Character.getType(ch), is any of the following:

Not all letters have case. Many characters are letters but are neither uppercase nor lowercase nor titlecase.

Parameters:
ch - the character to be tested.
Returns:
true if the character is a letter; false otherwise.
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 the specified character is a letter or digit.

A character is considered to be a letter or digit if either Character.isLetter(char ch) or Character.isDigit(char ch) returns true for the character.

Parameters:
ch - the character to be tested.
Returns:
true if the character is a letter or digit; false otherwise.
Since:
1.0.2
See Also:
isDigit(char), isJavaIdentifierPart(char), isJavaLetter(char), isJavaLetterOrDigit(char), isLetter(char), isUnicodeIdentifierPart(char)

isJavaLetter

public static boolean isJavaLetter(char ch)
Deprecated. Replaced by isJavaIdentifierStart(char).

Determines if the specified character is permissible as the first character in a Java identifier.

A character may start a Java identifier if and only if one of the following is true:

Parameters:
ch - the character to be tested.
Returns:
true if the character may start a Java identifier; false otherwise.
Since:
1.02
See Also:
isJavaLetterOrDigit(char), isJavaIdentifierStart(char), isJavaIdentifierPart(char), isLetter(char), isLetterOrDigit(char), isUnicodeIdentifierStart(char)

isJavaLetterOrDigit

public static boolean isJavaLetterOrDigit(char ch)
Deprecated. Replaced by isJavaIdentifierPart(char).

Determines if the specified character may be part of a Java identifier as other than the first character.

A character may be part of a Java identifier if and only if any of the following are true:

Parameters:
ch - the character to be tested.
Returns:
true if the character may be part of a Java identifier; false otherwise.
Since:
1.02
See Also:
isJavaLetter(char), isJavaIdentifierStart(char), isJavaIdentifierPart(char), isLetter(char), isLetterOrDigit(char), isUnicodeIdentifierPart(char), isIdentifierIgnorable(char)

isJavaIdentifierStart

public static boolean isJavaIdentifierStart(char ch)
Determines if the specified character is permissible as the first character in a Java identifier.

A character may start a Java identifier if and only if one of the following conditions is true:

Parameters:
ch - the character to be tested.
Returns:
true if the character may start a Java identifier; false otherwise.
Since:
1.1
See Also:
isJavaIdentifierPart(char), isLetter(char), isUnicodeIdentifierStart(char)

isJavaIdentifierPart

public static boolean isJavaIdentifierPart(char ch)
Determines if the specified character may be part of a Java identifier as other than the first character.

A character may be part of a Java identifier if any of the following are true:

Parameters:
ch - the character to be tested.
Returns:
true if the character may be part of a Java identifier; false otherwise.
Since:
1.1
See Also:
isIdentifierIgnorable(char), isJavaIdentifierStart(char), isLetterOrDigit(char), isUnicodeIdentifierPart(char)

isUnicodeIdentifierStart

public static boolean isUnicodeIdentifierStart(char ch)
Determines if the specified character is permissible as the first character in a Unicode identifier.

A character may start a Unicode identifier if and only if one of the following conditions is true:

Parameters:
ch - the character to be tested.
Returns:
true if the character may start a Unicode identifier; false otherwise.
Since:
1.1
See Also:
isJavaIdentifierStart(char), isLetter(char), isUnicodeIdentifierPart(char)

isUnicodeIdentifierPart

public static boolean isUnicodeIdentifierPart(char ch)
Determines if the specified character may be part of a Unicode identifier as other than the first character.

A character may be part of a Unicode identifier if and only if one of the following statements is true:

Parameters:
ch - the character to be tested.
Returns:
true if the character may be part of a Unicode identifier; false otherwise.
Since:
1.1
See Also:
isIdentifierIgnorable(char), isJavaIdentifierPart(char), isLetterOrDigit(char), isUnicodeIdentifierStart(char)

isIdentifierIgnorable

public static boolean isIdentifierIgnorable(char ch)
Determines if the specified character should be regarded as an ignorable character in a Java identifier or a Unicode identifier.

The following Unicode characters are ignorable in a Java identifier or a Unicode identifier:

Parameters:
ch - the character to be tested.
Returns:
true if the character is an ignorable control character that may be part of a Java or Unicode identifier; false otherwise.
Since:
1.1
See Also:
isJavaIdentifierPart(char), isUnicodeIdentifierPart(char)

toLowerCase

public static char toLowerCase(char ch)
Converts the character argument to lowercase using case mapping information from the UnicodeData file.

Note that Character.isLowerCase(Character.toLowerCase(ch)) does not always return true for some ranges of characters, particularly those that are symbols or ideographs.

Parameters:
ch - the character to be converted.
Returns:
the lowercase equivalent of the character, if any; otherwise, the character itself.
See Also:
isLowerCase(char), isUpperCase(char), toTitleCase(char), toUpperCase(char)

toUpperCase

public static char toUpperCase(char ch)
Converts the character argument to uppercase using case mapping information from the UnicodeData file.

Note that Character.isUpperCase(Character.toUpperCase(ch)) does not always return true for some ranges of characters, particularly those that are symbols or ideographs.

Parameters:
ch - the character to be converted.
Returns:
the uppercase equivalent of the character, if any; otherwise, the character itself.
See Also:
isLowerCase(char), isUpperCase(char), toLowerCase(char), toTitleCase(char)

toTitleCase

public static char toTitleCase(char ch)
Converts the character argument to titlecase using case mapping information from the UnicodeData file. If a character has no explicit titlecase mapping and is not itself a titlecase char according to UnicodeData, then the uppercase mapping is returned as an equivalent titlecase mapping. If the char argument is already a titlecase char, the same char value will be returned.

Note that Character.isTitleCase(Character.toTitleCase(ch)) does not always return true for some ranges of characters.

Parameters:
ch - the character to be converted.
Returns:
the titlecase equivalent of the character, if any; otherwise, the character itself.
Since:
1.0.2
See Also:
isTitleCase(char), toLowerCase(char), toUpperCase(char)

digit

public static int digit(char ch,
                        int radix)
Returns the numeric value of the character ch in the specified radix.

If the radix is not in the range MIN_RADIX <= radix <= MAX_RADIX or if the value of ch is not a valid digit in the specified radix, -1 is returned. A character is a valid digit if at least one of the following is true:

Parameters:
ch - the character to be converted.
radix - the radix.
Returns:
the numeric value represented by the character in the specified radix.
See Also:
forDigit(int, int), isDigit(char)

getNumericValue

public static int getNumericValue(char ch)
Returns the int value that the specified Unicode character represents. For example, the character '\u216C' (the roman numeral fifty) will return an int with a value of 50.

The letters A-Z in their uppercase ('\u0041' through '\u005A'), lowercase ('\u0061' through '\u007A'), and full width variant ('\uFF21' through '\uFF3A' and '\uFF41' through '\uFF5A') forms have numeric values from 10 through 35. This is independent of the Unicode specification, which does not assign numeric values to these char values.

If the character does not have a numeric value, then -1 is returned. If the character has a numeric value that cannot be represented as a nonnegative integer (for example, a fractional value), then -2 is returned.

Parameters:
ch - the character to be converted.
Returns:
the numeric value of the character, as a nonnegative int value; -2 if the character has a numeric value that is not a nonnegative integer; -1 if the character has no numeric value.
Since:
1.1
See Also:
forDigit(int, int), isDigit(char)

isSpace

public static boolean isSpace(char ch)
Deprecated. Replaced by isWhitespace(char).

Determines if the specified character is ISO-LATIN-1 white space. This method returns true for the following five characters only:
'\t' '\u0009' HORIZONTAL TABULATION
'\n' '\u000A' NEW LINE
'\f' '\u000C' FORM FEED
'\r' '\u000D' CARRIAGE RETURN
' ' '\u0020' SPACE

Parameters:
ch - the character to be tested.
Returns:
true if the character is ISO-LATIN-1 white space; false otherwise.
See Also:
isSpaceChar(char), isWhitespace(char)

isSpaceChar

public static boolean isSpaceChar(char ch)
Determines if the specified character is a Unicode space character. A character is considered to be a space character if and only if it is specified to be a space character by the Unicode standard. This method returns true if the character's general category type is any of the following:

Parameters:
ch - the character to be tested.
Returns:
true if the character is a space character; false otherwise.
Since:
1.1
See Also:
isWhitespace(char)

isWhitespace

public static boolean isWhitespace(char ch)
Determines if the specified character is white space according to Java. A character is a Java whitespace character if and only if it satisfies one of the following criteria:

Parameters:
ch - the character to be tested.
Returns:
true if the character is a Java whitespace character; false otherwise.
Since:
1.1
See Also:
isSpaceChar(char)

isISOControl

public static boolean isISOControl(char ch)
Determines if the specified character is an ISO control character. A character is considered to be an ISO control character if its code is in the range '\u0000' through '\u001F' or in the range '\u007F' through '\u009F'.

Parameters:
ch - the character to be tested.
Returns:
true if the character is an ISO control character; false otherwise.
Since:
1.1
See Also:
isSpaceChar(char), isWhitespace(char)

getType

public static int getType(char ch)
Returns a value indicating a character's general category.

Parameters:
ch - the character to be tested.
Returns:
a value of type int representing the character's general category.
Since:
1.1
See Also:
COMBINING_SPACING_MARK, CONNECTOR_PUNCTUATION, CONTROL, CURRENCY_SYMBOL, DASH_PUNCTUATION, DECIMAL_DIGIT_NUMBER, ENCLOSING_MARK, END_PUNCTUATION, FINAL_QUOTE_PUNCTUATION, FORMAT, INITIAL_QUOTE_PUNCTUATION, LETTER_NUMBER, LINE_SEPARATOR, LOWERCASE_LETTER, MATH_SYMBOL, MODIFIER_LETTER, MODIFIER_SYMBOL, NON_SPACING_MARK, OTHER_LETTER, OTHER_NUMBER, OTHER_PUNCTUATION, OTHER_SYMBOL, PARAGRAPH_SEPARATOR, PRIVATE_USE, SPACE_SEPARATOR, START_PUNCTUATION, SURROGATE, TITLECASE_LETTER, UNASSIGNED, UPPERCASE_LETTER

forDigit

public static char forDigit(int digit,
                            int radix)
Determines the character representation for a specific digit in the specified radix. If the value of radix is not a valid radix, or the value of digit is not a valid digit in the specified radix, the null character ('\u0000') is returned.

The radix argument is valid if it is greater than or equal to MIN_RADIX and less than or equal to MAX_RADIX. The digit argument is valid if 0 <=digit < radix.

If the digit is less than 10, then '0' + digit is returned. Otherwise, the value 'a' + digit - 10 is returned.

Parameters:
digit - the number to convert to a character.
radix - the radix.
Returns:
the char representation of the specified digit in the specified radix.
See Also:
MIN_RADIX, MAX_RADIX, digit(char, int)

getDirectionality

public static byte getDirectionality(char ch)
Returns the Unicode directionality property for the given character. Character directionality is used to calculate the visual ordering of text. The directionality value of undefined char values is DIRECTIONALITY_UNDEFINED.

Parameters:
ch - char for which the directionality property is requested.
Returns:
the directionality property of the char value.
Since:
1.4
See Also:
DIRECTIONALITY_UNDEFINED, DIRECTIONALITY_LEFT_TO_RIGHT, DIRECTIONALITY_RIGHT_TO_LEFT, DIRECTIONALITY_RIGHT_TO_LEFT_ARABIC, DIRECTIONALITY_EUROPEAN_NUMBER, DIRECTIONALITY_EUROPEAN_NUMBER_SEPARATOR, DIRECTIONALITY_EUROPEAN_NUMBER_TERMINATOR, DIRECTIONALITY_ARABIC_NUMBER, DIRECTIONALITY_COMMON_NUMBER_SEPARATOR, DIRECTIONALITY_NONSPACING_MARK, DIRECTIONALITY_BOUNDARY_NEUTRAL, DIRECTIONALITY_PARAGRAPH_SEPARATOR, DIRECTIONALITY_SEGMENT_SEPARATOR, DIRECTIONALITY_WHITESPACE, DIRECTIONALITY_OTHER_NEUTRALS, DIRECTIONALITY_LEFT_TO_RIGHT_EMBEDDING, DIRECTIONALITY_LEFT_TO_RIGHT_OVERRIDE, DIRECTIONALITY_RIGHT_TO_LEFT_EMBEDDING, DIRECTIONALITY_RIGHT_TO_LEFT_OVERRIDE, DIRECTIONALITY_POP_DIRECTIONAL_FORMAT

isMirrored

public static boolean isMirrored(char ch)
Determines whether the character is mirrored according to the Unicode specification. Mirrored characters should have their glyphs horizontally mirrored when displayed in text that is right-to-left. For example, '\u0028' LEFT PARENTHESIS is semantically defined to be an opening parenthesis. This will appear as a "(" in text that is left-to-right but as a ")" in text that is right-to-left.

Parameters:
ch - char for which the mirrored property is requested
Returns:
true if the char is mirrored, false if the char is not mirrored or is not defined.
Since:
1.4

compareTo

public int compareTo(Character anotherCharacter)
Compares two Character objects numerically.

Parameters:
anotherCharacter - the Character to be compared.
Returns:
the value 0 if the argument Character is equal to this Character; a value less than 0 if this Character is numerically less than the Character argument; and a value greater than 0 if this Character is numerically greater than the Character argument (unsigned comparison). Note that this is strictly a numerical comparison; it is not locale-dependent.
Since:
1.2

compareTo

public int compareTo(Object o)
Compares this Character object to another object. If the object is a Character, this function behaves like compareTo(Character). Otherwise, it throws a ClassCastException (as Character objects are comparable only to other Character objects).

Specified by:
compareTo in interface Comparable
Parameters:
o - the Object to be compared.
Returns:
the value 0 if the argument is a Character numerically equal to this Character; a value less than 0 if the argument is a Character numerically greater than this Character; and a value greater than 0 if the argument is a Character numerically less than this Character.
Throws:
ClassCastException - if the argument is not a Character.
Since:
1.2
See Also:
Comparable

JavaTM 2 Platform
Std. Ed. v1.4.2

Submit a bug or feature
For further API reference and developer documentation, see Java 2 SDK SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.

Copyright 2003 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.


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