The Java Tutorials have been written for JDK 8. Examples and practices described in this page don't take advantage of improvements introduced in later releases and might use technology no longer available.
See Java Language Changes for a summary of updated language features in Java SE 9 and subsequent releases.
See JDK Release Notes for information about new features, enhancements, and removed or deprecated options for all JDK releases.
Most of the time, if you are using a single character value, you will use the primitive char
type. For example:
char ch = 'a'; // Unicode for uppercase Greek omega character char uniChar = '\u03A9'; // an array of chars char[] charArray = { 'a', 'b', 'c', 'd', 'e' };
There are times, however, when you need to use a char as an objectfor example, as a method argument where an object is expected. The Java programming language provides a wrapper class that "wraps" the char
in a Character
object for this purpose. An object of type Character
contains a single field, whose type is char
. This
Character class also offers a number of useful class (that is, static) methods for manipulating characters.
You can create a Character
object with the Character
constructor:
Character ch = new Character('a');
The Java compiler will also create a Character
object for you under some circumstances. For example, if you pass a primitive char
into a method that expects an object, the compiler automatically converts the char
to a Character
for you. This feature is called autoboxingor unboxing, if the conversion goes the other way. For more information on autoboxing and unboxing, see
Autoboxing and Unboxing.
Character
class is immutable, so that once it is created, a Character
object cannot be changed.
The following table lists some of the most useful methods in the Character
class, but is not exhaustive. For a complete listing of all methods in this class (there are more than 50), refer to the
java.lang.Character API specification.
Method | Description |
---|---|
boolean isLetter(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) |
Determines whether the specified char value is uppercase or lowercase, respectively. |
char toUpperCase(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. |
A character preceded by a backslash (\) is an escape sequence and has special meaning to the compiler. The following table shows the Java 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 form feed 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
She said "Hello!" to me.
you would write
System.out.println("She said \"Hello!\" to me.");