What are the reasons for using wrapper classes?

• Working with collections: Primitive data types (int, double, etc.) cannot be stored in Java collections (such as ArrayList, HashMap, HashSet) that work only with objects. Wrapper classes provide an object representation of primitive types.
• Working with null: Primitive types cannot have a null value, whereas wrapper classes can. This is useful when an attribute's value may be unknown or absent.
• Class methods: Wrapper classes provide useful methods for working with the corresponding primitive values, such as parsing strings (Integer.parseInt(), Double.parseDouble()) or comparing values (Integer.compare()).
• Autoboxing/Unboxing: This feature allows the compiler to automatically convert primitive types to their wrapper classes and vice versa, simplifying code.
• Generics: In Java, generics work only with objects, not with primitive types. To create collections or methods that work with various numeric or other primitive types, wrapper classes are used.
• I/O operations: Some input/output streams in Java work with objects, requiring the use of wrapper classes.
• Synchronization: In multithreaded programming, locks (synchronized) can only be applied to objects, not to primitive types.

Example of using a wrapper class in a collection:

ArrayList<Integer> numbers = new ArrayList<>();
numbers.add(10); // Autoboxing: int 10 is converted to an Integer object
int firstNumber = numbers.get(0); // Unboxing: Integer object is converted back to int

Example of a wrapper class method:

String str = "123";
int num = Integer.parseInt(str); // Using static method for parsing