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public  final  class  java.lang.Character
    extends  java.lang.Object  (I-§1.12)
{
        // Fields
    public final static int MAX_RADIX;	§1.2.1
    public final static char MAX_VALUE;	§1.2.2
    public final static int MIN_RADIX;	§1.2.3
    public final static char MIN_VALUE;	§1.2.4

        // Constructors
    public Character(char  value);	§1.2.5

        // Methods
    public char charValue();	§1.2.6
    public static int digit(char  ch, int  radix);	§1.2.7
    public boolean equals(Object  obj);	§1.2.8
    public static char forDigit(int  digit, int  radix);	§1.2.9
    public int hashCode();	§1.2.10
    public static boolean isDefined(char  ch);	§1.2.11
    public static boolean isDigit(char  ch);	§1.2.12
    public static boolean isJavaLetter(char  ch);	§1.2.13
    public static boolean isJavaLetterOrDigit(char  ch);	§1.2.14
    public static boolean isLetter(char  ch);	§1.2.15
    public static boolean isLetterOrDigit(char  ch);	§1.2.16
    public static boolean isLowerCase(char  ch);	§1.2.17
    public static boolean isSpace(char  ch);	§1.2.18
    public static boolean isTitleCase(char  ch);	§1.2.19
    public static boolean isUpperCase(char  ch);	§1.2.20
    public static char toLowerCase(char  ch);	§1.2.21
    public String toString();	§1.2.22
    public static char toTitleCase(char  ch);	§1.2.23
    public static char toUpperCase(char  ch);	§1.2.24
}

In addition, this class provides a number of 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

The constant value of this field is the largest value permitted for the radix argument in radix-conversion methods such as the digit (I-§1.2.7) method, the forDigit (I-§1.2.9) method, and the toString (I-§1.8.21) method of class Integer.

MAX_VALUE¹

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

The constant value of this field is the smallest value permitted for the radix argument in radix-conversion methods such as the digit (I-§1.2.7) method, the forDigit (I-§1.2.9) method, and the toString (I-§1.8.21) method of class Integer.

MIN_VALUE²

The constant value of this field is the smallest value of 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 primitive char value represented by this object.

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

If the radix is not in the range or if the ch is not a valid digit in the specified radix, -1 is returned. A character is a valid digit if either of the following is true:

• The method isDigit (I-§1.2.12) 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 that . In this case, is returned.
• The character is one of the lowercase Latin letters 'a' through 'z' and its code is less that . In this case, 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 (I-§1.2.9).

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 (I-§1.12.3).

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 (I-§1.2.3) and less than or equal to MAX_RADIX (I-§1.2.1). The digit argument is valid if .

If the digit is less than 10, then is returned. Otherwise, the value 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:

digit (I-§1.2.7).

Returns:

a hash code value for this object.

Overrides:

hashCode in class Object (I-§1.12.6).

isDefined³

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
• Its value is in the range

Parameters:

ch - the character to be tested

Returns:

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

isDigit⁴

Determines whether the specified character is a digit. A character is considered to be a digit if it is not in the range '\u2000' through '\uu2000' and its Unicode name contains the word "DIGIT".

Parameters:

ch - the character to be tested

Returns:

true if the character is a digit; false otherwise.

isJavaLetter⁵

Determines whether 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:

isLetter (I-§1.2.15)
isLetterOrDigit (I-§1.2.16)
isJavaLetterOrDigit (I-§1.2.14).

isJavaLetterOrDigit⁶

Determines whether 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:

isLetter (I-§1.2.15)
isLetterOrDigit (I-§1.2.16)
isJavaLetter (I-§1.2.13).

Determines whether the specified character is a letter.

Note to the editor. Guy's book describes letter and letter/digit in excruciating detail. Do I need to do so also?

Parameters:

ch - the character to be tested

Returns:

true if the character is a letter; false otherwise.

See Also:

isJavaLetter (I-§1.2.13)
isJavaLetterOrDigit (I-§1.2.14).

isLetterOrDigit⁷

Parameters:

ch - the character to be tested

Returns:

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

See Also:

isDigit (I-§1.2.12)
isLetter (I-§1.2.15)
isJavaLetter (I-§1.2.13)
isJavaLetterOrDigit (I-§1.2.14).

isLowerCase⁸

Determines whether 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".

Parameters:

ch - the character to be tested

Returns:

true if the character is lowercase; false otherwise.

See Also:

isUpperCase (I-§1.2.20)
isTitleCase (I-§1.2.19)
toLowerCase (I-§1.2.21).

Determines if a character is 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.

isTitleCase⁹

Determines if the character is a titlecase character.

There are four Unicode characters whose printed representations look like pairs of Latin letters. For example, there is an uppercase letter that looks like "LJ" and the corresponding lowercase letter looks like "lj". A third form, which looks like "Lj" that 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:

isUpperCase (I-§1.2.20)
isLowerCase (I-§1.2.17)
toTitleCase (I-§1.2.23).

isUpperCase¹⁰

Determines whether 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".
• or the name for the character contains the words "CAPITAL LIGATURE".

Parameters:

ch - the character to be tested

Returns:

true if the character is uppercase; false otherwise.

See Also:

isLowerCase (I-§1.2.17)
isTitleCase (I-§1.2.19)
toUpperCase (I-§1.2.24).

toLowerCase¹¹

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' through '\u2FFF' have lowercase mappings; this method does map such characters to their lowercase equivalents even though the method isUpperCase (I-§1.2.20) 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 (I-§1.2.17).

Converts this Character object to a string. The result is a string whose length is 1 and whose sole component is the primitive char value represented by this object.

Returns:

a string representation of this object.

Overrides:

toString in class Object (I-§1.12.9).

toTitleCase¹²

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 (I-§1.2.19) does not return true for such characters.

Parameters:

ch - the character to be converted

Returns:

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

See Also:

isTitleCase (I-§1.2.19).

toUpperCase¹³

Converts the character argument to uppercase. A character has an uppercase 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 '\u2000FFF' have uppercase mappings; this method does map such characters to their titlecase equivalents even though the method isLowerCase (I-§1.2.17) 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:

isUpperCase (I-§1.2.20).

² This field is new in Java 1.1.

³ This method is new in Java 1.1.

⁴ In Version 1.0, this version returns true only for the ten ASCII digits `0' through '9'.

⁵ This method is new in Java 1.1

⁶ This method is new in Java 1.1

⁷ This method is new in Java 1.1

⁸ In Version 1.0, this version returns true only for lowercase characters in the range '\u0000' to '\u00FF'.

⁹ This method is new in Java 1.1.

¹⁰ In Java 1.0, this method returns true only for uppercase characters in the range '\u0000' to '\u00FF'.

¹¹ In Java 1.0, this method only works on characters in the range '\u0000' to '\u00FF'. For characters outisde this range, the method returns its argument unchanged.

¹² This method is new in Java 1.1

¹³ In Java 1.0, this method only works on characters in the range '\u0000' to '\u00FF'. For characters outside this range, the method returns its argument unchanged.

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