Wrapper classes

Wrapper classes in Java are used to convert primitive data types into objects (i.e., wrapping primitive values) so that they can be included in Java collections, passed as method arguments where objects are required, and used in other situations where objects are needed instead of primitives. Each primitive data type in Java has a corresponding wrapper class. Here are the wrapper classes for primitive data types:

1. Byte: `java.lang.Byte`

2. Short: `java.lang.Short`

3. Integer: `java.lang.Integer`

4. Long: `java.lang.Long`

5. Float: `java.lang.Float`

6. Double: `java.lang.Double`

7. Character: `java.lang.Character`

8. Boolean: `java.lang.Boolean`

Wrapper classes provide methods to perform various operations on the wrapped primitive value, such as converting it to other data types, comparing values, and parsing strings to primitive values. They also provide constants for representing the maximum and minimum values of the corresponding primitive data type.

Here's an example demonstrating the usage of wrapper classes:

public class WrapperExample {

    public static void main(String[] args) {

        // Using wrapper classes to convert primitive data types to objects

        Integer intValue = Integer.valueOf(10);

        Double doubleValue = Double.valueOf(5.5);

        Character charValue = Character.valueOf('A');

        Boolean boolValue = Boolean.valueOf(true);

        // Using wrapper classes to perform operations

        int sum = intValue + Integer.valueOf(20); // Unboxing intValue to int

        double product = doubleValue * Double.valueOf(2.0); // Unboxing doubleValue to double

        // Using wrapper class constants

        int maxIntValue = Integer.MAX_VALUE;

        double minDoubleValue = Double.MIN_VALUE;

        // Printing values

        System.out.println("Sum: " + sum);

        System.out.println("Product: " + product);

        System.out.println("Max Integer Value: " + maxIntValue);

        System.out.println("Min Double Value: " + minDoubleValue);

    }

}

In this example:

- We create wrapper class objects using the `valueOf()` method.

- We perform operations using both primitive values and wrapper class objects. Automatic unboxing is performed to convert wrapper class objects to primitive values when necessary.

- We access constants representing the maximum and minimum values of primitive data types using wrapper class constants.