Character | Java In A Nutshell, 5th Edition

Character

java.lang

Java 1.0

serializable comparable

This class provides an immutable object wrapper around the primitive char data type. charValue( ) returns the char value of a Character object. The compareTo( ) method implements the Comparable interface so that Character objects can be ordered and sorted. The static methods are the most interesting thing about this class, however: they categorize char values based on the categories defined by the Unicode standard. (Some of the methods are only useful if you have a detailed understanding of that standard.) Static methods beginning with "is" test whether a character is in a given category. isDigit( ) , isLetter( ) , isWhitespace( ) , isUpperCase( ) and isLowerCase( ) are some of the most useful. Note that these methods work for any Unicode character, not just with the familiar Latin letters and Arabic numbers of the ASCII character set. getType( ) returns a constant that identifies the category of a character. getdirectionality( ) returns a separate DIRECTIONALITY_ constant that specifies the "directionality category" of a character.

In addition to testing the category of a character, this class also defines static methods for converting characters . toUpperCase( ) returns the uppercase equivalent of the specified character (or returns the character itself if the character is uppercase or has no uppercase equivalent). toLowerCase( ) converts instead to lowercase. digit( ) returns the integer equivalent of a given character in a given radix (or base; for example, use 16 for hexadecimal). It works with any Unicode digit character, and also (for sufficiently large radix values) the ASCII letters a-z and A-Z. forDigit( ) returns the ASCII character that corresponds to the specified value (0-35) for the specified radix. getNumericValue( ) is similar, but also works with any Unicode character including those, such as Roman numerals, that represent numbers but are not decimal digits. Finally, the static toString( ) method returns a String of length 1 that contains the specified char value.

Java 5.0 introduces many new methods to this class to accommodate Unicode supplementary characters that use 21 bits and do not fit in a single char value. The two representations for these supplementary characters are as an int codepoint in the range 0 through 0x10ffff, or as a sequence of two char values known as a "surrogate pair." The first char of such a pair should fall in the "high surrogate" range and the second char should fall in the "low surrogate" range. toChars( ) converts an int codepoint into one or two char values. toCodePoint( ) , codePointAt( ) , and codePointBefore( ) convert one or two char values into the corresponding int value. codePointCount( ) returns the number of characters in a char array or CharSequence , counting surrogate pairs as a single supplementary character. offsetByCodePoints( ) tells you how many char indexes to advance in a run of text if you want to skip over the specified number of code points. Finally, the various character type testing and case conversion methods such as isWhitespace( ) and toUpperCase( ) are available in new versions that take an int codepoint argument instead of a single char argument.

Figure 10-9. java.lang.Character

 public final class  Character  implements Serializable, Comparable<Character> {  // Public Constructors  public  Character  (char  value  );  // Public Constants   1.1  public static final byte  COMBINING_SPACING_MARK  ;  =8   1.1  public static final byte  CONNECTOR_PUNCTUATION  ;  =23   1.1  public static final byte  CONTROL  ;  =15   1.1  public static final byte  CURRENCY_SYMBOL  ;  =26   1.1  public static final byte  DASH_PUNCTUATION  ;  =20   1.1  public static final byte  DECIMAL_DIGIT_NUMBER  ;  =9   1.4  public static final byte  DIRECTIONALITY_ARABIC_NUMBER  ;  =6   1.4  public static final byte  DIRECTIONALITY_BOUNDARY_NEUTRAL  ;  =9   1.4  public static final byte  DIRECTIONALITY_COMMON_NUMBER_SEPARATOR  ;  =7   1.4  public static final byte  DIRECTIONALITY_EUROPEAN_NUMBER  ;  =3   1.4  public static final byte  DIRECTIONALITY_EUROPEAN_NUMBER_SEPARATOR  ;  =4   1.4  public static final byte  DIRECTIONALITY_EUROPEAN_NUMBER_TERMINATOR  ;  =5   1.4  public static final byte  DIRECTIONALITY_LEFT_TO_RIGHT  ;  =0   1.4  public static final byte  DIRECTIONALITY_LEFT_TO_RIGHT_EMBEDDING  ;  =14   1.4  public static final byte  DIRECTIONALITY_LEFT_TO_RIGHT_OVERRIDE  ;  =15   1.4  public static final byte  DIRECTIONALITY_NONSPACING_MARK  ;  =8   1.4  public static final byte  DIRECTIONALITY_OTHER_NEUTRALS  ;  =13   1.4  public static final byte  DIRECTIONALITY_PARAGRAPH_SEPARATOR  ;  =10   1.4  public static final byte  DIRECTIONALITY_POP_DIRECTIONAL_FORMAT  ;  =18   1.4  public static final byte  DIRECTIONALITY_RIGHT_TO_LEFT  ;  =1   1.4  public static final byte  DIRECTIONALITY_RIGHT_TO_LEFT_ARABIC  ;  =2   1.4  public static final byte  DIRECTIONALITY_RIGHT_TO_LEFT_EMBEDDING  ;  =16   1.4  public static final byte  DIRECTIONALITY_RIGHT_TO_LEFT_OVERRIDE  ;  =17   1.4  public static final byte  DIRECTIONALITY_SEGMENT_SEPARATOR  ;  =11   1.4  public static final byte  DIRECTIONALITY_UNDEFINED  ;  =-1   1.4  public static final byte  DIRECTIONALITY_WHITESPACE  ;  =12   1.1  public static final byte  ENCLOSING_MARK  ;  =7   1.1  public static final byte  END_PUNCTUATION  ;  =22   1.4  public static final byte  FINAL_QUOTE_PUNCTUATION  ;  =30   1.1  public static final byte  FORMAT  ;  =16   1.4  public static final byte  INITIAL_QUOTE_PUNCTUATION  ;  =29   1.1  public static final byte  LETTER_NUMBER  ;  =10   1.1  public static final byte  LINE_SEPARATOR  ;  =13   1.1  public static final byte  LOWERCASE_LETTER  ;  =2   1.1  public static final byte  MATH_SYMBOL  ;  =25   5.0  public static final int  MAX_CODE_POINT  ;  =1114111   5.0  public static final char  MAX_HIGH_SURROGATE  ;  =  \uDBFF  5.0  public static final char  MAX_LOW_SURROGATE  ;  =  \uDFFF       public static final int  MAX_RADIX  ;  =36   5.0  public static final char  MAX_SURROGATE  ;  =  \uDFFF       public static final char  MAX_VALUE  ;  =  \uFFFF  5.0  public static final int  MIN_CODE_POINT  ;  =0   5.0  public static final char  MIN_HIGH_SURROGATE  ;  =  \uD800  5.0  public static final char  MIN_LOW_SURROGATE  ;  =  \uDC00       public static final int  MIN_RADIX  ;  =2   5.0  public static final int  MIN_SUPPLEMENTARY_CODE_POINT  ;  =65536   5.0  public static final char  MIN_SURROGATE  ;  =  \uD800       public static final char  MIN_VALUE  ;  =   public final class  Character  implements Serializable, Comparable<Character> {  // Public Constructors  public  Character  (char  value  );  // Public Constants   1.1  public static final byte  COMBINING_SPACING_MARK  ;  =8   1.1  public static final byte  CONNECTOR_PUNCTUATION  ;  =23   1.1  public static final byte  CONTROL  ;  =15   1.1  public static final byte  CURRENCY_SYMBOL  ;  =26   1.1  public static final byte  DASH_PUNCTUATION  ;  =20   1.1  public static final byte  DECIMAL_DIGIT_NUMBER  ;  =9   1.4  public static final byte  DIRECTIONALITY_ARABIC_NUMBER  ;  =6   1.4  public static final byte  DIRECTIONALITY_BOUNDARY_NEUTRAL  ;  =9   1.4  public static final byte  DIRECTIONALITY_COMMON_NUMBER_SEPARATOR  ;  =7   1.4  public static final byte  DIRECTIONALITY_EUROPEAN_NUMBER  ;  =3   1.4  public static final byte  DIRECTIONALITY_EUROPEAN_NUMBER_SEPARATOR  ;  =4   1.4  public static final byte  DIRECTIONALITY_EUROPEAN_NUMBER_TERMINATOR  ;  =5   1.4  public static final byte  DIRECTIONALITY_LEFT_TO_RIGHT  ;  =0   1.4  public static final byte  DIRECTIONALITY_LEFT_TO_RIGHT_EMBEDDING  ;  =14   1.4  public static final byte  DIRECTIONALITY_LEFT_TO_RIGHT_OVERRIDE  ;  =15   1.4  public static final byte  DIRECTIONALITY_NONSPACING_MARK  ;  =8   1.4  public static final byte  DIRECTIONALITY_OTHER_NEUTRALS  ;  =13   1.4  public static final byte  DIRECTIONALITY_PARAGRAPH_SEPARATOR  ;  =10   1.4  public static final byte  DIRECTIONALITY_POP_DIRECTIONAL_FORMAT  ;  =18   1.4  public static final byte  DIRECTIONALITY_RIGHT_TO_LEFT  ;  =1   1.4  public static final byte  DIRECTIONALITY_RIGHT_TO_LEFT_ARABIC  ;  =2   1.4  public static final byte  DIRECTIONALITY_RIGHT_TO_LEFT_EMBEDDING  ;  =16   1.4  public static final byte  DIRECTIONALITY_RIGHT_TO_LEFT_OVERRIDE  ;  =17   1.4  public static final byte  DIRECTIONALITY_SEGMENT_SEPARATOR  ;  =11   1.4  public static final byte  DIRECTIONALITY_UNDEFINED  ;  =-1   1.4  public static final byte  DIRECTIONALITY_WHITESPACE  ;  =12   1.1  public static final byte  ENCLOSING_MARK  ;  =7   1.1  public static final byte  END_PUNCTUATION  ;  =22   1.4  public static final byte  FINAL_QUOTE_PUNCTUATION  ;  =30   1.1  public static final byte  FORMAT  ;  =16   1.4  public static final byte  INITIAL_QUOTE_PUNCTUATION  ;  =29   1.1  public static final byte  LETTER_NUMBER  ;  =10   1.1  public static final byte  LINE_SEPARATOR  ;  =13   1.1  public static final byte  LOWERCASE_LETTER  ;  =2   1.1  public static final byte  MATH_SYMBOL  ;  =25   5.0  public static final int  MAX_CODE_POINT  ;  =1114111   5.0  public static final char  MAX_HIGH_SURROGATE  ;  =  \uDBFF  5.0  public static final char  MAX_LOW_SURROGATE  ;  =  \uDFFF public static final int  MAX_RADIX  ;  =36   5.0  public static final char  MAX_SURROGATE  ;  =  \uDFFF public static final char  MAX_VALUE  ;  =  \uFFFF  5.0  public static final int  MIN_CODE_POINT  ;  =0   5.0  public static final char  MIN_HIGH_SURROGATE  ;  =  \uD800  5.0  public static final char  MIN_LOW_SURROGATE  ;  =  \uDC00 public static final int  MIN_RADIX  ;  =2   5.0  public static final int  MIN_SUPPLEMENTARY_CODE_POINT  ;  =65536   5.0  public static final char  MIN_SURROGATE  ;  =  \uD800 public static final char  MIN_VALUE  ;  =  \0  1.1  public static final byte  MODIFIER_LETTER  ;  =4   1.1  public static final byte  MODIFIER_SYMBOL  ;  =27   1.1  public static final byte  NON_SPACING_MARK  ;  =6   1.1  public static final byte  OTHER_LETTER  ;  =5   1.1  public static final byte  OTHER_NUMBER  ;  =11   1.1  public static final byte  OTHER_PUNCTUATION  ;  =24   1.1  public static final byte  OTHER_SYMBOL  ;  =28   1.1  public static final byte  PARAGRAPH_SEPARATOR  ;  =14   1.1  public static final byte  PRIVATE_USE  ;  =18   5.0  public static final int  SIZE  ;  =16   1.1  public static final byte  SPACE_SEPARATOR  ;  =12   1.1  public static final byte  START_PUNCTUATION  ;  =21   1.1  public static final byte  SURROGATE  ;  =19   1.1  public static final byte  TITLECASE_LETTER  ;  =3   1.1  public static final Class<Character>  TYPE  ;  1.1  public static final byte  UNASSIGNED  ;  =0   1.1  public static final byte  UPPERCASE_LETTER  ;  =1   // Nested Types   1.2  public static class  Subset  ;  1.2  public static final class  UnicodeBlock  extends Character.Subset;  // Public Class Methods   5.0  public static int  charCount  (int  codePoint  );  5.0  public static int  codePointAt  (char[ ]  a  , int  index  );  5.0  public static int  codePointAt  (CharSequence  seq  , int  index  );  5.0  public static int  codePointAt  (char[ ]  a  , int  index  , int  limit  );  5.0  public static int  codePointBefore  (CharSequence  seq  , int  index  );  5.0  public static int  codePointBefore  (char[ ]  a  , int  index  );  5.0  public static int  codePointBefore  (char[ ]  a  , int  index  , int  start  );  5.0  public static int  codePointCount  (char[ ]  a  , int  offset  , int  count  );  5.0  public static int  codePointCount  (CharSequence  seq  , int  beginIndex  , int  endIndex  );  5.0  public static int  digit  (int  codePoint  , int  radix  ); public static int  digit  (char  ch  , int  radix  ); public static char  forDigit  (int  digit  , int  radix  );  1.4  public static byte  getDirectionality  (char  ch  );  5.0  public static byte  getDirectionality  (int  codePoint  );  1.1  public static int  getNumericValue  (char  ch  );  5.0  public static int  getNumericValue  (int  codePoint  );  1.1  public static int  getType  (char  ch  );  5.0  public static int  getType  (int  codePoint  );  5.0  public static boolean  isDefined  (int  codePoint  ); public static boolean  isDefined  (char  ch  );  5.0  public static boolean  isDigit  (int  codePoint  ); public static boolean  isDigit  (char  ch  );  5.0  public static boolean  isHighSurrogate  (char  ch  );  5.0  public static boolean  isIdentifierIgnorable  (int  codePoint  );  1.1  public static boolean  isIdentifierIgnorable  (char  ch  );  1.1  public static boolean  isISOControl  (char  ch  );  5.0  public static boolean  isISOControl  (int  codePoint  );  1.1  public static boolean  isJavaIdentifierPart  (char  ch  );  5.0  public static boolean  isJavaIdentifierPart  (int  codePoint  );  1.1  public static boolean  isJavaIdentifierStart  (char  ch  );  5.0  public static boolean  isJavaIdentifierStart  (int  codePoint  ); public static boolean  isLetter  (char  ch  );  5.0  public static boolean  isLetter  (int  codePoint  ); public static boolean  isLetterOrDigit  (char  ch  );  5.0  public static boolean  isLetterOrDigit  (int  codePoint  );  5.0  public static boolean  isLowerCase  (int  codePoint  ); public static boolean  isLowerCase  (char  ch  );  5.0  public static boolean  isLowSurrogate  (char  ch  );  5.0  public static boolean  isMirrored  (int  codePoint  );  1.4  public static boolean  isMirrored  (char  ch  );  5.0  public static boolean  isSpaceChar  (int  codePoint  );  1.1  public static boolean  isSpaceChar  (char  ch  );  5.0  public static boolean  isSupplementaryCodePoint  (int  codePoint  );  5.0  public static boolean  isSurrogatePair  (char  high  , char  low  ); public static boolean  isTitleCase  (char  ch  );  5.0  public static boolean  isTitleCase  (int  codePoint  );  1.1  public static boolean  isUnicodeIdentifierPart  (char  ch  );  5.0  public static boolean  isUnicodeIdentifierPart  (int  codePoint  );  5.0  public static boolean  isUnicodeIdentifierStart  (int  codePoint  );  1.1  public static boolean  isUnicodeIdentifierStart  (char  ch  ); public static boolean  isUpperCase  (char  ch  );  5.0  public static boolean  isUpperCase  (int  codePoint  );  5.0  public static boolean  isValidCodePoint  (int  codePoint  );  5.0  public static boolean  isWhitespace  (int  codePoint  );  1.1  public static boolean  isWhitespace  (char  ch  );  5.0  public static int  offsetByCodePoints  (CharSequence  seq  , int  index  , int  codePointOffset  );  5.0  public static int  offsetByCodePoints  (char[ ]  a  , int  start  , int  count  , int  index  , int  codePointOffset  );  5.0  public static char  reverseBytes  (char  ch  );  5.0  public static char[ ]  toChars  (int  codePoint  );  5.0  public static int  toChars  (int  codePoint  , char[ ]  dst  , int  dstIndex  );  5.0  public static int  toCodePoint  (char  high  , char  low  ); public static char  toLowerCase  (char  ch  );  5.0  public static int  toLowerCase  (int  codePoint  );  1.4  public static String  toString  (char  c  ); public static char  toTitleCase  (char  ch  );  5.0  public static int  toTitleCase  (int  codePoint  ); public static char  toUpperCase  (char  ch  );  5.0  public static int  toUpperCase  (int  codePoint  );  5.0  public static Character  valueOf  (char  c  );  // Public Instance Methods  public char  charValue  ( );  // Methods Implementing Comparable   1.2  public int  compareTo  (Character  anotherCharacter  );  // Public Methods Overriding Object  public boolean  equals  (Object  obj  ); public int  hashCode  ( ); public String  toString  ( );  // Deprecated Public Methods   #  public static boolean  isJavaLetter  (char  ch  );  #  public static boolean  isJavaLetterOrDigit  (char  ch  );  #  public static boolean  isSpace  (char  ch  ); } 
  1.1  public static final byte  MODIFIER_LETTER  ;  =4   1.1  public static final byte  MODIFIER_SYMBOL  ;  =27   1.1  public static final byte  NON_SPACING_MARK  ;  =6   1.1  public static final byte  OTHER_LETTER  ;  =5   1.1  public static final byte  OTHER_NUMBER  ;  =11   1.1  public static final byte  OTHER_PUNCTUATION  ;  =24   1.1  public static final byte  OTHER_SYMBOL  ;  =28   1.1  public static final byte  PARAGRAPH_SEPARATOR  ;  =14   1.1  public static final byte  PRIVATE_USE  ;  =18   5.0  public static final int  SIZE  ;  =16   1.1  public static final byte  SPACE_SEPARATOR  ;  =12   1.1  public static final byte  START_PUNCTUATION  ;  =21   1.1  public static final byte  SURROGATE  ;  =19   1.1  public static final byte  TITLECASE_LETTER  ;  =3   1.1  public static final Class<Character>  TYPE  ;  1.1  public static final byte  UNASSIGNED  ;  =0   1.1  public static final byte  UPPERCASE_LETTER  ;  =1   // Nested Types   1.2  public static class  Subset  ;  1.2  public static final class  UnicodeBlock  extends Character.Subset;  // Public Class Methods   5.0  public static int  charCount  (int  codePoint  );  5.0  public static int  codePointAt  (char[ ]  a  , int  index  );  5.0  public static int  codePointAt  (CharSequence  seq  , int  index  );  5.0  public static int  codePointAt  (char[ ]  a  , int  index  , int  limit  );  5.0  public static int  codePointBefore  (CharSequence  seq  , int  index  );  5.0  public static int  codePointBefore  (char[ ]  a  , int  index  );  5.0  public static int  codePointBefore  (char[ ]  a  , int  index  , int  start  );  5.0  public static int  codePointCount  (char[ ]  a  , int  offset  , int  count  );  5.0  public static int  codePointCount  (CharSequence  seq  , int  beginIndex  , int  endIndex  );  5.0  public static int  digit  (int  codePoint  , int  radix  );        public static int  digit  (char  ch  , int  radix  );        public static char  forDigit  (int  digit  , int  radix  );  1.4  public static byte  getDirectionality  (char  ch  );  5.0  public static byte  getDirectionality  (int  codePoint  );  1.1  public static int  getNumericValue  (char  ch  );  5.0  public static int  getNumericValue  (int  codePoint  );  1.1  public static int  getType  (char  ch  );  5.0  public static int  getType  (int  codePoint  );  5.0  public static boolean  isDefined  (int  codePoint  );        public static boolean  isDefined  (char  ch  );  5.0  public static boolean  isDigit  (int  codePoint  );        public static boolean  isDigit  (char  ch  );  5.0  public static boolean  isHighSurrogate  (char  ch  );  5.0  public static boolean  isIdentifierIgnorable  (int  codePoint  );  1.1  public static boolean  isIdentifierIgnorable  (char  ch  );  1.1  public static boolean  isISOControl  (char  ch  );  5.0  public static boolean  isISOControl  (int  codePoint  );  1.1  public static boolean  isJavaIdentifierPart  (char  ch  );  5.0  public static boolean  isJavaIdentifierPart  (int  codePoint  );  1.1  public static boolean  isJavaIdentifierStart  (char  ch  );  5.0  public static boolean  isJavaIdentifierStart  (int  codePoint  );        public static boolean  isLetter  (char  ch  );  5.0  public static boolean  isLetter  (int  codePoint  );        public static boolean  isLetterOrDigit  (char  ch  );  5.0  public static boolean  isLetterOrDigit  (int  codePoint  );  5.0  public static boolean  isLowerCase  (int  codePoint  );        public static boolean  isLowerCase  (char  ch  );  5.0  public static boolean  isLowSurrogate  (char  ch  );  5.0  public static boolean  isMirrored  (int  codePoint  );  1.4  public static boolean  isMirrored  (char  ch  );  5.0  public static boolean  isSpaceChar  (int  codePoint  );  1.1  public static boolean  isSpaceChar  (char  ch  );  5.0  public static boolean  isSupplementaryCodePoint  (int  codePoint  );  5.0  public static boolean  isSurrogatePair  (char  high  , char  low  );        public static boolean  isTitleCase  (char  ch  );  5.0  public static boolean  isTitleCase  (int  codePoint  );  1.1  public static boolean  isUnicodeIdentifierPart  (char  ch  );  5.0  public static boolean  isUnicodeIdentifierPart  (int  codePoint  );  5.0  public static boolean  isUnicodeIdentifierStart  (int  codePoint  );  1.1  public static boolean  isUnicodeIdentifierStart  (char  ch  );        public static boolean  isUpperCase  (char  ch  );  5.0  public static boolean  isUpperCase  (int  codePoint  );  5.0  public static boolean  isValidCodePoint  (int  codePoint  );  5.0  public static boolean  isWhitespace  (int  codePoint  );  1.1  public static boolean  isWhitespace  (char  ch  );  5.0  public static int  offsetByCodePoints  (CharSequence  seq  , int  index  ,        int  codePointOffset  );  5.0  public static int  offsetByCodePoints  (char[ ]  a  , int  start  , int  count  ,        int  index  , int  codePointOffset  );  5.0  public static char  reverseBytes  (char  ch  );  5.0  public static char[ ]  toChars  (int  codePoint  );  5.0  public static int  toChars  (int  codePoint  , char[ ]  dst  , int  dstIndex  );  5.0  public static int  toCodePoint  (char  high  , char  low  );        public static char  toLowerCase  (char  ch  );  5.0  public static int  toLowerCase  (int  codePoint  );  1.4  public static String  toString  (char  c  );        public static char  toTitleCase  (char  ch  );  5.0  public static int  toTitleCase  (int  codePoint  );        public static char  toUpperCase  (char  ch  );  5.0  public static int  toUpperCase  (int  codePoint  );  5.0  public static Character  valueOf  (char  c  );  // Public Instance Methods  public char  charValue  ( );  // Methods Implementing Comparable   1.2  public int  compareTo  (Character  anotherCharacter  );  // Public Methods Overriding Object  public boolean  equals  (Object  obj  );        public int  hashCode  ( );        public String  toString  ( );  // Deprecated Public Methods   #  public static boolean  isJavaLetter  (char  ch  );  #  public static boolean  isJavaLetterOrDigit  (char  ch  );  #  public static boolean  isSpace  (char  ch  );   }