Class java.lang.Character

public final class Character

extends Object

implements Serializable

In addition, this class provides several methods for determining the type of a character and converting characters from uppercase to lowercase and vice versa.

Many of the methods of class Character are defined in terms of a "Unicode attribute table" that specifies a name for every defined Unicode code point. The table also includes other attributes, such as a decimal value, an uppercase equivalent, a lowercase equivalent, and/or a titlecase equivalent. The Unicode attribute table is available on the World Wide Web as the file:

ftp://unicode.org/pub/MappingTables/UnicodeData1.1.5.txt

For a more detailed specification of the Character class, one that encompasses the exact behavior of methods such as isDigit, isLetter, isLowerCase, and isUpperCase over the full range of Unicode values, see Gosling, Joy, and Steele, The Java Language Specification.

COMBINING_SPACING_MARK

CONNECTOR_PUNCTUATION

CONTROL

CURRENCY_SYMBOL

DASH_PUNCTUATION

DECIMAL_DIGIT_NUMBER

ENCLOSING_MARK

END_PUNCTUATION

FORMAT

LETTER_NUMBER

LINE_SEPARATOR

LOWERCASE_LETTER

MATH_SYMBOL

MAX_RADIX

The maximum radix available for conversion to and from Strings.

MAX_VALUE

The constant value of this field is the largest value of type char.

MIN_RADIX

The minimum radix available for conversion to and from Strings.

MIN_VALUE

The constant value of this field is the smallest value of type char.

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

TYPE

The Class object representing the primitive type char.

UNASSIGNED

UPPERCASE_LETTER

Character(char)

Constructs a Character object and initializes it so that it represents the primitive value argument.

charValue()

Returns the value of this Character object.

digit(char, int)

Returns the numeric value of the character ch in the specified radix.

equals(Object)

Compares this object against the specified object.

forDigit(int, int)

Determines the character representation for a specific digit in the specified radix.

getNumericValue(char)

Returns the Unicode numeric value of the character as a nonnegative integer.

getType(char)

Returns a value indicating a character category.

hashCode()

Returns a hash code for this Character.

isDefined(char)

Determines if a character has a defined meaning in Unicode.

isDigit(char)

Determines if the specified character is a digit.

isIdentifierIgnorable(char)

Determines if the specified character should be regarded as an ignorable character in a Java identifier or a Unicode identifier.

isISOControl(char)

Determines if the specified character is an ISO control character.

isJavaIdentifierPart(char)

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

isJavaIdentifierStart(char)

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

isJavaLetter(char)

Determines if the specified character is a "Java" letter, that is, the character is permissible as the first character in an identifier in the Java language. Deprecated.

isJavaLetterOrDigit(char)

Determines if the specified character is a "Java" letter or digit, that is, the character is permissible as a non-initial character in an identifier in the Java language. Deprecated.

isLetter(char)

Determines if the specified character is a letter.

isLetterOrDigit(char)

Determines if the specified character is a letter or digit.

isLowerCase(char)

Determines if the specified character is a lowercase character.

isSpace(char)

Determines if the specified character is ISO-LATIN-1 white space. Deprecated.

isSpaceChar(char)

Determines if the specified character is a Unicode space character.

isTitleCase(char)

Determines if the specified character is a titlecase character.

isUnicodeIdentifierPart(char)

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

isUnicodeIdentifierStart(char)

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

isUpperCase(char)

Determines if the specified character is an uppercase character.

isWhitespace(char)

Determines if the specified character is white space according to Java.

toLowerCase(char)

The given character is mapped to its lowercase equivalent; if the character has no lowercase equivalent, the character itself is returned.

toString()

Returns a String object representing this character's value.

toTitleCase(char)

Converts the character argument to titlecase.

toUpperCase(char)

Converts the character argument to uppercase.

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, forDigit, toString, valueOf

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, forDigit, toString, valueOf

The constant value of this field is the smallest value of type char.

The constant value of this field is the largest value of type char.

The Class object representing the primitive type char.

Constructs a Character object and initializes it so that it represents the primitive value argument.

Parameters:

value - value for the new Character object.

Returns the value of this Character object.

Returns:

the primitive char value represented by this object.

Returns a hash code for this Character.

Returns:

a hash code value for this object.

Overrides:

hashCode in class Object

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.

Parameters:

obj - the object to compare with.

Returns:

true if the objects are the same; false otherwise.

Overrides:

equals in class Object

Returns a String object representing this character's value. Converts this Character object to a string. The result is a string whose length is 1. The string's sole component is the primitive char value represented by this object.

Returns:

a string representation of this object.

Overrides:

toString in class Object

Determines if the specified character is a lowercase character. A character is lowercase if it is not in the range '\u2000' through '\u2FFF', the Unicode attribute table does not specify a mapping to lowercase for the character, and at least one of the following is true:

• The attribute table specifies a mapping to uppercase for the character.
• The name for the character contains the words "SMALL LETTER".
• The name for the character contains the words "SMALL LIGATURE".

A character is considered to be lowercase if and only if it is specified to be lowercase by the Unicode 2.0 standard (category "Ll" in the Unicode specification data file).

Of the ISO-LATIN-1 characters (character codes 0x0000 through 0x00FF), the following are lowercase:

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, isTitleCase, toLowerCase

Determines if the specified character is an uppercase character. A character is uppercase if it is not in the range '\u2000' through '\u2FFF', the Unicode attribute table does not specify a mapping to uppercase for the character, and at least one of the following is true:

• The attribute table specifies a mapping to lowercase for the character.
• The name for the character contains the words "CAPITAL LETTER".
• The name for the character contains the words "CAPITAL LIGATURE".

Of the ISO-LATIN-1 characters (character codes 0x0000 through 0x00FF), the following are uppercase:

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.

See Also:

isLowerCase, isTitleCase, toUpperCase

Determines if the specified character is a titlecase character. A character is considered to be titlecase if and only if it is specified to be titlecase by the Unicode 2.0 standard (category "Lt" in the Unicode specification data file).

The printed representations of four Unicode 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 the Unicode characters for which this method returns true:

• LATIN CAPITAL LETTER D WITH SMALL LETTER Z WITH CARON
• LATIN CAPITAL LETTER L WITH SMALL LETTER J
• LATIN CAPITAL LETTER N WITH SMALL LETTER J
• LATIN CAPITAL LETTER D WITH SMALL LETTER Z

Parameters:

ch - the character to be tested.

Returns:

true if the character is titlecase; false otherwise.

See Also:

isLowerCase, isUpperCase, toTitleCase

Determines if the specified character is a digit. A character is considered to be a digit if it is not in the range '\u2000' <= ch <= '\u2FFF' and its Unicode name contains the word "DIGIT". For a more complete specification that encompasses all Unicode characters that are defined as digits, see Gosling, Joy, and Steele, The Java Language Specification.

These are the ranges of Unicode characters that are considered digits:

0x0030 through 0x0039	ISO-LATIN-1 digits ('0' through '9')
0x0660 through 0x0669	Arabic-Indic digits
0x06F0 through 0x06F9	Extended Arabic-Indic digits
0x0966 through 0x096F	Devanagari digits
0x09E6 through 0x09EF	Bengali digits
0x0A66 through 0x0A6F	Gurmukhi digits
0x0AE6 through 0x0AEF	Gujarati digits
0x0B66 through 0x0B6F	Oriya digits
0x0BE7 through 0x0BEF	Tamil digits
0x0C66 through 0x0C6F	Telugu digits
0x0CE6 through 0x0CEF	Kannada digits
0x0D66 through 0x0D6F	Malayalam digits
0x0E50 through 0x0E59	Thai digits
0x0ED0 through 0x0ED9	Lao digits
0x0F20 through 0x0F29	Tibetan digits
0xFF10 through 0xFF19	Fullwidth digits

Parameters:

ch - the character to be tested.

Returns:

true if the character is a digit; false otherwise.

See Also:

digit, forDigit

Determines if a character has a defined meaning in Unicode. A character is defined if at least one of the following is true:

• It has an entry in the Unicode attribute table.
• Its value is in the range '\u3040' <= ch <= '\u9FA5'.
• Its value is in the range '\uF900' <= ch <= '\uFA2D'.

Parameters:

ch - the character to be tested

Returns:

true if the character has a defined meaning in Unicode; false otherwise.

See Also:

isDigit, isLetter, isLetterOrDigit, isLowerCase, isTitleCase, isUpperCase

Determines if the specified character is a letter. For a more complete specification that encompasses all Unicode characters, see Gosling, Joy, and Steele, The Java Language Specification.

A character is considered to be a letter if and only if it is specified to be a letter by the Unicode 2.0 standard (category "Lu", "Ll", "Lt", "Lm", or "Lo" in the Unicode specification data file).

Note that most ideographic characters are considered to be letters (category "Lo") for this purpose.

Note also that not all letters have case: many Unicode 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, isJavaIdentifierStart, isJavaLetter, isJavaLetterOrDigit, isLetterOrDigit, isLowerCase, isTitleCase, isUnicodeIdentifierStart, isUpperCase

Determines if the specified character is a letter or digit. For a more complete specification that encompasses all Unicode characters, see Gosling, Joy, and Steele, The Java Language Specification.

A character is considered to be a letter if and only if it is specified to be a letter or a digit by the Unicode 2.0 standard (category "Lu", "Ll", "Lt", "Lm", "Lo", or "Nd" in the Unicode specification data file). In other words, isLetterOrDigit is true of a character if and only if either isLetter is true of the character or isDigit is true of the character.

Parameters:

ch - the character to be tested.

Returns:

true if the character is a letter or digit; false otherwise.

See Also:

isDigit, isJavaIdentifierPart, isJavaLetter, isJavaLetterOrDigit, isLetter, isUnicodeIdentifierPart

Note: isJavaLetter() is deprecated. Replaced by isJavaIdentifierStart(char).

Determines if the specified character is a "Java" letter, that is, the character is permissible as the first character in an identifier in the Java language.

A character is considered to be a Java letter if and only if it is a letter, the ASCII dollar sign character '$', or the underscore character '_'.

Parameters:

ch - the character to be tested.

Returns:

true if the character is a Java letter; false otherwise.

See Also:

isJavaIdentifierStart, isJavaLetterOrDigit, isLetter, isLetterOrDigit, isUnicodeIdentifierStart

Note: isJavaLetterOrDigit() is deprecated. Replaced by isJavaIdentifierPart(char).

Determines if the specified character is a "Java" letter or digit, that is, the character is permissible as a non-initial character in an identifier in the Java language.

A character is considered to be a Java letter or digit if and only if it is a letter, a digit, the ASCII dollar sign character '$', or the underscore character '_'.

Parameters:

ch - the character to be tested.

Returns:

true if the character is a Java letter or digit; false otherwise.

See Also:

isJavaIdentifierPart, isJavaLetter, isLetter, isLetterOrDigit, isUnicodeIdentifierPart

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 it is one of the following:

• a letter
• a currency symbol (such as "$")
• a connecting punctuation character (such as "_").

Parameters:

ch - the character to be tested.

Returns:

true if the character may start a Java identifier; false otherwise.

See Also:

isJavaIdentifierPart, isLetter, isUnicodeIdentifierStart

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 it is one of the following:

• a letter
• a currency symbol (such as "$")
• a connecting punctuation character (such as "_").
• a digit
• a numeric letter (such as a Roman numeral character)
• a combining mark
• a non-spacing mark
• an ignorable control character

Parameters:

ch - the character to be tested.

Returns:

true if the character may be part of a Unicode identifier; false otherwise.

See Also:

isIdentifierIgnorable, isJavaIdentifierStart, isLetterOrDigit, isUnicodeIdentifierPart

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 it is a letter.

Parameters:

ch - the character to be tested.

Returns:

true if the character may start a Unicode identifier; false otherwise.

See Also:

isJavaIdentifierStart, isLetter, isUnicodeIdentifierPart

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 it is one of the following:

• a letter
• a connecting punctuation character (such as "_").
• a digit
• a numeric letter (such as a Roman numeral character)
• a combining mark
• a non-spacing mark
• an ignorable control character

Parameters:

ch - the character to be tested.

Returns:

true if the character may be part of a Unicode identifier; false otherwise.

See Also:

isIdentifierIgnorable, isJavaIdentifierPart, isLetterOrDigit, isUnicodeIdentifierStart

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:

0x0000 through 0x0008,	ISO control characters that
0x000E through 0x001B,	are not whitespace
and 0x007F through 0x009F
0x200C through 0x200F	join controls
0x200A through 0x200E	bidirectional controls
0x206A through 0x206F	format controls
0xFEFF	zero-width no-break space

Parameters:

ch - the character to be tested.

Returns:

true if the character may be part of a Unicode identifier; false otherwise.

See Also:

isJavaIdentifierPart, isUnicodeIdentifierPart

The given character is mapped to its lowercase equivalent; if the character has no lowercase equivalent, the character itself is returned.

A character has a lowercase equivalent if and only if a lowercase mapping is specified for the character in the Unicode attribute table.

Note that some Unicode characters in the range '\u2000' to '\u2FFF' have lowercase mappings; this method does map such characters to their lowercase equivalents even though the method isUpperCase does not return true for such characters.

Parameters:

ch - the character to be converted.

Returns:

the lowercase equivalent of the character, if any; otherwise the character itself.

See Also:

isLowerCase, isUpperCase, toTitleCase, toUpperCase

Converts the character argument to uppercase. A character has an uppercase equivalent if and only if an uppercase mapping is specified for the character in the Unicode attribute table.

Note that some Unicode characters in the range '\u2000' to '\u2000FFF' have uppercase mappings; this method does map such characters to their titlecase equivalents even though the method isLowerCase does not return true for such characters.

Parameters:

ch - the character to be converted.

Returns:

the uppercase equivalent of the character, if any; otherwise the character itself.

See Also:

isLowerCase, isUpperCase, toLowerCase, toTitleCase

Converts the character argument to titlecase. A character has a titlecase equivalent if and only if a titlecase mapping is specified for the character in the Unicode attribute table.

Note that some Unicode characters in the range '\u2000' through '\u2FFF' have titlecase mappings; this method does map such characters to their titlecase equivalents even though the method isTitleCase does not return true for such characters.

There are only four Unicode characters that are truly titlecase forms that are distinct from uppercase forms. As a rule, if a character has no true titlecase equivalent but does have an uppercase mapping, then the Unicode 2.0 attribute table specifies a titlecase mapping that is the same as the uppercase mapping.

Parameters:

ch - the character to be converted.

Returns:

the titlecase equivalent of the character, if any; otherwise the character itself.

See Also:

isTitleCase, toLowerCase, toUpperCase

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:

• The method isDigit is true of the character and the Unicode decimal digit value of the character (or its single-character decomposition) is less than the specified radix. In this case the decimal digit value is returned.
• The character is one of the uppercase Latin letters 'A' through 'Z' and its code is less than radix + 'A' - 10. In this case, ch - 'A' + 10 is returned.
• The character is one of the lowercase Latin letters 'a' through 'z' and its code is less than radix + 'a' - 10. In this case, ch - 'a' + 10 is returned.

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, isDigit

Returns the Unicode numeric value of the character as a nonnegative integer. 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.

radix - the radix.

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.

See Also:

forDigit, isDigit

Note: isSpace() is 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, isWhitespace

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 2.0 standard (category "Zs", "Zl, or "Zp" in the Unicode specification data file).

Parameters:

ch - the character to be tested.

Returns:

true if the character is a space character; false otherwise.

See Also:

isWhitespace

Determines if the specified character is white space according to Java. A character is considered to be a Java whitespace character if and only if it satisfies one of the following criteria:

• It is a Unicode space separator (category "Zs"), but is not a no-break space (\u00A0 or \uFEFF).
• It is a Unicode line separator (category "Zl").
• It is a Unicode paragraph separator (category "Zp").
• It is \u0009, HORIZONTAL TABULATION.
• It is \u000A, LINE FEED.
• It is \u000B, VERTICAL TABULATION.
• It is \u000C, FORM FEED.
• It is \u000D, CARRIAGE RETURN.
• It is \u001C, FILE SEPARATOR.
• It is \u001D, GROUP SEPARATOR.
• It is \u001E, RECORD SEPARATOR.
• It is \u001F, UNIT SEPARATOR.

Parameters:

ch - the character to be tested.

Returns:

true if the character is a Java whitespace character; false otherwise.

See Also:

isSpaceChar

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.

See Also:

isSpaceChar, isWhitespace

Returns a value indicating a character category.

Parameters:

ch - the character to be tested.

Returns:

a value of type int, the character category.

See Also:

COMBINING_SPACING_MARK, CONNECTOR_PUNCTUATION, CONTROL, CURRENCY_SYMBOL, DASH_PUNCTUATION, DECIMAL_DIGIT_NUMBER, ENCLOSING_MARK, END_PUNCTUATION, FORMAT, 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

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