Wrapper Class In Java

In Java, a wrapper class is a class that wraps (encapsulates) primitive data types within an object.

The purpose of wrapper classes is to provide a way to treat primitive data types as objects.

The Java platform provides a set of built-in wrapper classes for each primitive data type:

Byte: Wraps a byte value.
Short: Wraps a short value.
Integer: Wraps an int value.
Long: Wraps a long value.
Float: Wraps a float value.
Double: Wraps a double value.
Character: Wraps a char value.
Boolean: Wraps a boolean value.

Wrapper classes are particularly useful when we need to work with collections (such as ArrayList or HashMap) that can only store objects, not primitive types.

They are also commonly used in APIs that require objects rather than primitive types.

Wrapper classes provide methods to convert between primitive types and objects, as well as to perform various operations on the wrapped values.

Wrapper Classes Example:

Integer wrapper class example.

Example:

public class WrapperClassesExample {
    public static void main(String[] args) {

        // Creating wrapper objects
        Integer intWrapper = new Integer(10);
        

        // Accessing values and performing operations
        int intValue = intWrapper.intValue();
        

        // Printing values
        System.out.println("Integer value: " + intValue);  
       // Output: Integer value: 10
        

        // Using static methods for conversion
        int parsedInt = Integer.parseInt("123");
        

        System.out.println("Parsed int: " + parsedInt); 
        // Output: Parsed int: 123
        
    }
}

Example:

public class WrapperClassesExample {
    public static void main(String[] args) {

        // Creating wrapper objects
        Double doubleWrapper = new Double(3.14);

        // Accessing values and performing operations
        double doubleValue = doubleWrapper.doubleValue();

        // Printing values
        System.out.println("Double value: " + doubleValue);  
        // Output: Double value: 3.14

        // Using static methods for conversion
        double parsedDouble = Double.parseDouble("3.14");

        System.out.println("Parsed double: " + parsedDouble); 
        // Output: Parsed double: 3.14
    }
}

Example:

public class WrapperClassesExample {
    public static void main(String[] args) {

        // Creating wrapper objects
        Character charWrapper = new Character('A');

        // Accessing values and performing operations
        char charValue = charWrapper.charValue();

        // Printing values
        System.out.println("Character value: " + charValue);  
        // Output: Character value: A

    }
}

Example:

public class WrapperClassesExample {
    public static void main(String[] args) {

        // Creating wrapper objects
        Boolean boolWrapper = new Boolean(true);

        // Accessing values and performing operations
        boolean boolValue = boolWrapper.booleanValue();

        // Printing values
        System.out.println("Boolean value: " + boolValue); 
        // Output: Boolean value: true

    }
}

Double wrapper class example.

Character wrapper class example.

Boolean wrapper class example.

Note:

In addition to constructors and methods for converting between primitive types and objects, wrapper classes also provide methods for arithmetic operations, comparison, and other utilities.

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