Character Class in Java

Introduction to Character Class in Java

In the java. lang package, Java includes a wrapper class called Character. An object of type Character has only a field with the type char. The Character class provides several practical class (i.e., static) methods for manipulating characters.

The Wrapper class in Java helps to convert primitive into object and object into primitive.

Java offers the following 8 wrapper classes:

Learn more about wrapper classes here

In this post, we'll talk about Java's Character Class, which wraps the value of primitive data type char into its object. Each Character object can contain a single char field.

The Unicode Data file, updated by the Unicode Consortium, contains all of the Character class's attributes, methods, and constructors.

Unicode is a universal encoding scheme for written characters and text that enables the exchange of data internationally.

**The Unicode Consortium, a non-profit organization, is dedicated to the advancement, upkeep, and advocacy of software internationalization standards and data. A central focus of its work is the Unicode Standard, a comprehensive specification governing text representation across contemporary software platforms and industry standards.

A Character class instance or object can contain individual character data. In addition, this wrapper class also provides some useful methods for manipulating, inspecting, or processing single-character data.

The character set from U+0000 to U+FFFF is sometimes called the Basic Multilingual Plane (or BMP). Characters with CodePoints greater than U+FFFF are called supplementary characters.

The Java language typically represents char arrays in Strings or String Buffers using the UTF-16 encoding method. In this type of representation, additional characters are displayed as character pairs. The first character is displayed from the high surrogate area (\uD800-\uDBFF), and the second from the low surrogate area (\uDc00-\uDBFF).

How to Add Character Object in Java

The Character class proviseveralr of convenient (static) class methods for manipulating characters. Let's see how we can create a Character object using the Character constructor.

character ch = newcharacter('a');

Now, you may wonder, what would happen if we pass a primitive character to a method that expects an object? In that case, the Java compiler automatically converts it to a character.

This feature is called Autoboxing or Unboxing

Autoboxing It is conversion of a primitive value into an object of the its wrapper class is called Autoboxing

Unboxing, It is converting an object of a wrapper type to its corresponding primitive value

Learn more about Autoboxing here

Character num = new Character('2');

In the example above, the Java compiler internally creates a drawing object for the programmer. When passing a value of the primary data type (char) to a user-defined method that is ready to accept an argument as an object, the compiler automatically converts the passed char value to a character value (which is, it becomes an object).

Another example,

Now, just like the String class, Character class is immutable, i.e, once an object is created, it cannot be changed

An immutable object is an object whose internal state remains same after it has been entirely created.

Learn more about why string is immutable in Java here

The above syntax can also be written as:

Methods of Character Class in Java

The methods of Character class are as follows:

1.boolean isLetter(char ch):

Syntax:

Here, ch is a primitive character passed as a parameter to this method to determine whether ch is an alphabet. If it is, the method returns true; if not, it returns false.

Example:

Output

Since A is an alphabet, the isLetter() method returns true, whereas it returns false for 0, which is not an alphabet

2. boolean isDigit(char ch):

Syntax:

Here, ch as a primitive character is passed as a parameter to this method. This method would return true if ch is a digit and return false if it's not

Let's see an example in Java:

Output

Since A is not a digit, the isDigit() method returns false, whereas it returns true for 0, which clearly is a digit.

3. boolean isWhitespace(char ch):

Syntax:

Here again, we've passed ch as a parameter to this method which is supposed to return true if it encounters whitespace and false if it does not

Let's see an example in Java:

Output

Here, we see that the isWhitespace() method returns true for the following: '': space, which is a whitespace character in ASCII '\n': newline is also one of the whitespace characters in ASCII '\t': tab is another whitespace character in ASCII 9: Since the codepoint,9 is a whitespace character

In ASCII, carriage return '\r', vertical tab '\v', and formfeed '\f' are also considered to be whitespace characters.

4. boolean isUpperCase(char ch):

Syntax:

ch is passed as a parameter, this method returns true if it's in upper case and returns false otherwise.

Let's see an example in Java:

Output

Here, we see that it returns true for A and the ASCII value of A, which is 65; however, it returns false for `a', which is in lowercase.

5. boolean isLowerCase(char ch):

Syntax:

ch is passed as a primitive character. This method returns true if ch is lowercase and false otherwise.

Let's see an example in Java:

Output

Clearly, it returns true for a and ASCII value of a and returns false for A which is it hehe per case.

6. char toUpperCase(char ch):

Syntax:

1

Let's see an example in Java:

Output

A
65
48

Here, we rly see that the parameters have changed to upper case, where 97 (ASCII of a) was passed, it changes to 48 which is an ASCII of A

7. char toLowerCase(char ch):

Syntax:

This method takes ch as a paramter and returns the lowercase form of the specified char value.

Let's see an example in Java:

Output

Here, we can see that the parameters have changed to lower case, where 65 (ASCII of A) was passed, it changes to 97 which is an ASCII of a

8. toString(char ch):

Syntax:

this method takes ch, a primitive character, as a parameter and returns a string object

Let's see an example in Java

Output

Here, X and Y are returned as strings in the output

Let's now see some more methods of Character class in Java

Applications of Character Class in Java

Let's see an example in Java

Why Then Is There A Need For Character class?

During development, we come across situations where you need to use objects instead of primitive data types

Why do We Have to do This?

You may need to modify or apply different methods to character variables. You can only do this if you cast the value to an immutable object. The java.util package handles wrapper classes.

Character class is a kind of wrapper class like we've talked about before.

A wrapper class is a class that wraps(converts) a primitive datatype to an object.

But then, why would we want to convert a primitive data type into an object?

Often we need to change/apply different methods to a character variable which is not possible unless we convert the said value into an immutable object

Character class in Java provides that needed immutability where once the value of a character datatype is changed to a character object it cannot be reverted back to its form.

Examples of Character Class in Java

Let's look at some examples of implementing character classes in Java

Example 1

Let's implement various methods like charCount(), hashCode(), isDigit() etc in the Java code below

Output:

Here, as we can see we let the user provide 4 inputs to the program stored in value1, value2, value3, and value4 respectively.

We then generate it's character count value using charCount(), hashcode using hashCode(), checking whether it's a digit using isDigit() or an ISO control using isISOControl()

Example 2

Let's look at a Java example of implementing methods like isLetter(), isLowerCase(), isSpace(), and isDefined().

Output

Four char primitives ch1, ch2, ch3, and ch4 are created and are assigned some values. Four methods isLetter(ch1), isLowerCase(ch2), isSpace(ch3), isDefined(ch3) are used upon these objects, and their results are stored in boolean variables like b1, b2, b3 and b4 and are then printed.