Explain the concept of a wrapper class for primitive data types.

A wrapper class in Java is a class that encapsulates a primitive data type (such as int, boolean, char) into an object. This allows primitives to be used where objects are required, for example, in collections.

Java provides wrapper classes for all primitives:

• Integer for int
• Boolean for boolean
• Character for char
• and so on.

Advantages:

• They allow primitives to be used in collections that only work with objects (e.g., ArrayList<Integer>).
• They provide methods for conversion and working with primitives.

Example:

int a = 5;
Integer aWrapper = Integer.valueOf(a); // boxing

int b = aWrapper.intValue(); // unboxing

ArrayList<Integer> list = new ArrayList<>();
list.add(a); // auto-boxing: int is automatically boxed into Integer

Thus, wrapper classes provide object-oriented handling of primitive types.