With Java 1.5, autoboxing and unboxing are introduced to automatically convert the primitive type into boxed wrappers or vice versa.
Autoboxing: It is the process of converting primitives to their corresponding object type automatically.
Unboxing: It is the process of converting object types to their corresponding primitives automatically.
int intA = 5; Integer integerA = intA; // autoboxing Integer integerB = 10; int intB = integerB; //unboxing
Why do we need autoboxing and unboxing?
Unfortunatelly, having primitives in Java is nothing to do with object oriented programming. The only reason comes into mind is performance, since all local primitives are allocated in jvm stack(fast) whereas all objects are preserved in heap(referenced/slow).
Primitives are generally different in size whereas since object wrappers are just references, they are equal in size.
As of Java 8 you cannot use primitives for generic types.
List<int> myList = new ArrayList<>(); //compilation error List<Integer> myList = new ArrayList<>(); //successfully compiled
The reason is that the generic types are compiled to object which have to have same size.
For conveince Java provides us autoboxing and unboxing so that we can work with primitives and generic types with ease.
List<Integer> myList = new ArrayList<>(); int a =5; myList.add(a); //autoboxing int b = myList.get(0); //unboxing System.out.println(b); //5