Most of the time, if you are using a single character value, you will use the primitivechar
type. For example:There are times, however, when you need to use a char as an object—for example, as a method argument where an object is expected. The Java programming language provides a wrapper class that "wraps" thechar ch = 'a'; char uniChar = '\u039A'; // Unicode for uppercase Greek omega character char[] charArray ={ 'a', 'b', 'c', 'd', 'e' }; // an array of charschar
in aCharacter
object for this purpose. An object of typeCharacter
contains a single field, whose type ischar
. ThisCharacter
class also offers a number of useful class (i.e., static) methods for manipulating characters.You can create a
Character
object with theCharacter
constructor:The Java compiler will also create aCharacter ch = new Character('a');Character
object for you under some circumstances. For example, if you pass a primitivechar
into a method that expects an object, the compiler automatically converts thechar
to aCharacter
for you. This feature is called autoboxing—or unboxing, if the conversion goes the other way.Here is an example of boxing,
and here is an example of both boxing and unboxing,Character ch = 'a'; // the primitive char 'a' is boxed into the Character object chCharacter test(Character c) {...} // method parameter and return type = Character object char c = test('x'); // primitive 'x' is boxed for method test, return is unboxed to char 'c'The following table lists some of the most useful methods in the
Note: TheCharacter
class is immutable, so that once it is created, aCharacter
object cannot be changed.Character
class, but is not exhaustive. For a complete listing of all methods in this class (there are more than 50), refer to thejava.lang.Character
API specification.
Useful Methods in the Character
ClassMethod Description boolean isLetter(char ch)
boolean isDigit(char ch)Determines whether the specified char value is a letter or a digit, respectively. boolean isWhiteSpace(char ch)
Determines whether the specified char value is white space. boolean isUpperCase(char ch)
boolean isLowerCase(char ch)Determines whether the specified char value is uppercase or lowercase, respectively. char toUpperCase(char ch)
char toLowerCase(char ch)Returns the uppercase or lowercase form of the specified char value. toString(char ch)
Returns a String
object representing the specified character value—that is, a one-character string.Escape Sequences
A character preceded by a backslash (\) is an escape sequence and has special meaning to the compiler. The newline character (\n
) has been used frequently in this tutorial inSystem.out.println()
statements to advance to the next line after the string is printed. The following table shows the Java escape sequences:
Escape Sequences Escape Sequence Description \t
Insert a tab in the text at this point. \b
Insert a backspace in the text at this point. \n
Insert a newline in the text at this point. \r
Insert a carriage return in the text at this point. \f
Insert a formfeed in the text at this point. \'
Insert a single quote character in the text at this point. \"
Insert a double quote character in the text at this point. \\
Insert a backslash character in the text at this point. When an escape sequence is encountered in a print statement, the compiler interprets it accordingly. For example, if you want to put quotes within quotes you must use the escape sequence, \", on the interior quotes. To print the sentence
you would writeShe said "Hello!" to me.System.out.println("She said \"Hello!\" to me.");