Java - Character Class

Example:

char ch = 'a';

// Unicode for uppercase Greek omega character
char uniChar = '\u039A';

// an array of chars
char[] charArray ={ 'a', 'b', 'c', 'd', 'e' };

However in development, we come across situations where we need to use objects instead of primitive data types. In order to achieve this, Java provides wrapper class Character for primitive data type char.

The Character class offers a number of useful class (i.e., 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 autoboxing or unboxing, if the conversion goes the other way.

Similarities Between int & char Data Types
A char is effectively an unsigned 16-bit integer type in Java.

Like other integer types, you can perform an assignment conversion from an integer constant to any integer type so long as it's in the appropriate range.

This allows you to perform integer operations on char variables, as each char variable has a int value that corresponds to it's Unicode Code Point. int can be cast/converted to char and char can be cast/converted to int

Example:

// Here following primitive char 'a'
// is boxed into the Character object ch
Character ch = 'a';

// Here primitive 'x' is boxed for method test,
// return is unboxed to char 'c'
char c = test('x');

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 in System.out.println() statements to advance to the next line after the string is printed.

Following table shows the Java escape sequences:

Escape Sequence	Description
\t	Inserts a tab in the text at this point.
\b	Inserts a backspace in the text at this point.
\n	Inserts a newline in the text at this point.
\r	Inserts a carriage return in the text at this point.
\f	Inserts a form feed in the text at this point.
\'	Inserts a single quote character in the text at this point.
\"	Inserts a double quote character in the text at this point.
\\	Inserts a backslash character in the text at this point.

When an escape sequence is encountered in a print statement, the compiler interprets it accordingly.

Example:

If you want to put quotes within quotes you must use the escape sequence, \", on the interior quotes:

public class Test {

   public static void main(String args[]) {
      System.out.println("She said \"Hello!\" to me.");
   }
}

This would produce the following result:

She said "Hello!" to me.

Character Methods:

Here is the list of the important instance methods that all the subclasses of the Character class implement:

SN	Methods with Description
1	isLetter() Determines whether the specified char value is a letter.
2	isDigit() Determines whether the specified char value is a digit.
3	isWhitespace() Determines whether the specified char value is white space.
4	isUpperCase() Determines whether the specified char value is uppercase.
5	isLowerCase() Determines whether the specified char value is lowercase.
6	toUpperCase() Returns the uppercase form of the specified char value.
7	toLowerCase() Returns the lowercase form of the specified char value.
8	toString() Returns a String object representing the specified character valuethat is, a one-character string.

For a complete list of methods, please refer to the java.lang.Character API specification.

Example: Incrementing Char Variables

In Java, char is a numeric type. When you add 1 to a char, you get to the next unicode code point. In case of 'A', the next code point is 'B'.

char testCharOne = 'A';
testCharOne++;

System.out.print(testCharOne.toString());

Result : B

Example: Comparing Char Variables - Checking Alphabetic Order of Characters in String

  public boolean checkAlphabeticOrder(String content) {
      boolean isAlphabetic = true;

      for (int i = 0; i < content.length() - 1; i++) {

          char currentChar = content.charAt(i);
          char nextChar = content.charAt(i + 1);

          if (Character.toLowerCase(currentChar) > Character.toLowerCase(nextChar)) {

              isAlphabetic = false;

              /* If "currentChar" is greater than "nextChar", this means that the Unicode Code
              Point/Value of "currentChar" is greater than the Unicode
              Code Point/Value of "nextChar".The Unicode Code Point/Values of letters increase
              with their position in the alphabet. Therefore "a" has a smaller value than "z".

              However due to the way Unicode is designed letter cases
              (e.g upper and lowercase letters) have different values. Uppercase letters
              regardless of their position in the alphabet will
              ALWAYS have a greater value than lowercase letters. For example "z", will have
              a greater value than "A", which is why the Character.toLowerCase() method is used to
              accureately compare characters. */
          }
      }
      return isAlphabetic;
  }
}

Result : B

What is Next?

In the next section, we will be going through the String class in Java. You will be learning how to declare and use Strings efficiently as well as some of the important methods in the String class.

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