Character Wrapper Class in Java

The Character class in Java is a wrapper class for the primitive data type char. It provides numerous utility methods for character operations. This class is found in the java.lang package.

Key Features of Character Wrapper Class

1. Immutability: Instances of the Character class are immutable, meaning their value cannot be changed once assigned.
2. Static Methods: The Character class provides a number of static methods to perform operations on characters.
3. Character Information: Methods to determine character type (e.g., digit, letter, whitespace, etc.).
4. Character Conversion: Methods to convert characters between cases, to digit, etc.

Character Class Methods

Here are some commonly used methods in the Character class:

1. char charValue()
2. int compareTo(Character anotherCharacter)
3. boolean equals(Object obj)
4. int hashCode()
5. String toString()
6. boolean isDigit(char ch)
7. boolean isLetter(char ch)
8. boolean isLetterOrDigit(char ch)
9. boolean isLowerCase(char ch)
10. boolean isUpperCase(char ch)
11. char toLowerCase(char ch)
12. char toUpperCase(char ch)

1. char charValue()

Returns the value of this Character object as a char.

public class CharacterExample {
    public static void main(String[] args) {
        Character ch = 'a';
        char c = ch.charValue();
        System.out.println(c);  // Output: a
    }
}

Output:

a

2. int compareTo(Character anotherCharacter)

Compares two Character objects numerically.

public class CharacterExample {
    public static void main(String[] args) {
        Character ch1 = 'a';
        Character ch2 = 'b';
        System.out.println(ch1.compareTo(ch2));  // Output: -1
    }
}

Output:

-1

3. boolean equals(Object obj)

Compares this object against the specified object.

public class CharacterExample {
    public static void main(String[] args) {
        Character ch1 = 'a';
        Character ch2 = 'a';
        System.out.println(ch1.equals(ch2));  // Output: true
    }
}

Output:

true

4. int hashCode()

Returns a hash code for this Character.

public class CharacterExample {
    public static void main(String[] args) {
        Character ch = 'a';
        System.out.println(ch.hashCode());  // Output: 97
    }
}

Output:

97

5. String toString()

Returns a String object representing this Character's value.

public class CharacterExample {
    public static void main(String[] args) {
        Character ch = 'a';
        System.out.println(ch.toString());  // Output: a
    }
}

Output:

a

6. boolean isDigit(char ch)

Determines if the specified character is a digit.

public class CharacterExample {
    public static void main(String[] args) {
        System.out.println(Character.isDigit('1'));  // Output: true
        System.out.println(Character.isDigit('a'));  // Output: false
    }
}

Output:

true
false

7. boolean isLetter(char ch)

Determines if the specified character is a letter.

public class CharacterExample {
    public static void main(String[] args) {
        System.out.println(Character.isLetter('a'));  // Output: true
        System.out.println(Character.isLetter('1'));  // Output: false
    }
}

Output:

true
false

8. boolean isLetterOrDigit(char ch)

Determines if the specified character is a letter or digit.

public class CharacterExample {
    public static void main(String[] args) {
        System.out.println(Character.isLetterOrDigit('a'));  // Output: true
        System.out.println(Character.isLetterOrDigit('1'));  // Output: true
        System.out.println(Character.isLetterOrDigit('@'));  // Output: false
    }
}

Output:

true
true
false

9. boolean isLowerCase(char ch)

Determines if the specified character is a lowercase letter.

public class CharacterExample {
    public static void main(String[] args) {
        System.out.println(Character.isLowerCase('a'));  // Output: true
        System.out.println(Character.isLowerCase('A'));  // Output: false
    }
}

Output:

true
false

10. boolean isUpperCase(char ch)

Determines if the specified character is an uppercase letter.

public class CharacterExample {
    public static void main(String[] args) {
        System.out.println(Character.isUpperCase('A'));  // Output: true
        System.out.println(Character.isUpperCase('a'));  // Output: false
    }
}

Output:

true
false

11. char toLowerCase(char ch)

Converts the specified character to lowercase.

public class CharacterExample {
    public static void main(String[] args) {
        System.out.println(Character.toLowerCase('A'));  // Output: a
        System.out.println(Character.toLowerCase('a'));  // Output: a
    }
}

Output:

a
a

12. char toUpperCase(char ch)

Converts the specified character to uppercase.

public class CharacterExample {
    public static void main(String[] args) {
        System.out.println(Character.toUpperCase('a'));  // Output: A
        System.out.println(Character.toUpperCase('A'));  // Output: A
    }
}

Output:

A
A

Conclusion

The Character class in Java provides a variety of methods for character manipulation and type checking. Understanding and utilizing these methods can greatly aid in text processing and data validation tasks.