What are the reasons for using wrapper classes in programming?

Wrapper classes are used for the following purposes:

• Converting primitive types to objects: In Java and other languages with primitive data types (int, boolean, float, etc.) and objects, wrappers allow working with primitives as objects. This is necessary, for example, for using them in collections (List, Map) that store only objects.
• Providing additional methods: Wrapper classes often provide useful methods for working with the corresponding primitive types. For example, Integer has methods for parsing strings into numbers, converting to different numeral systems, etc.
• Handling null values: Wrapper objects can hold null, which is impossible for primitive types. This is important when working with databases or external data sources where fields can be empty.
• Generics: When working with generics (e.g., List<Integer>, Map<String, Boolean>), it is necessary to use classes rather than primitive types. Wrappers allow using parameterized types with primitive values.
• Autoboxing and unboxing: Java has a mechanism for automatic conversion between primitive types and their corresponding wrapper classes, simplifying code writing.

// Example of Autoboxing and Unboxing
Integer i = 10; // Autoboxing: int 10 is automatically converted to Integer
int j = i;      // Unboxing: Integer i is automatically converted to int

• Creating immutable objects: Wrappers are often used to create immutable representations of primitive types. For example, String objects or wrapper classes for primitives are immutable.
• Use in input/output streams: Some input/output streams (e.g., ObjectOutputStream) work only with objects, which requires using wrappers to write primitive data.