Primitives vs Objects: The Magic of Java Wrapper Classes

Wrapper class :

A Wrapper class is a class that wraps a primitive data type inside an object. In Java, primitive types like int, double, char etc. are not objects — but sometimes Java needs objects (like in Collections).

Primitive vs Wrapper class:
int - Integer
double - Double
char - Character
boolean - Boolean
float - Float
long - Long
byte - Byte
short - Short

Autoboxing :

-The java automatically converts primitive to object.
Ex:

int x = 5(primitive) → auto → Integer obj = 5 

Unboxing :

• The java automatically converts object to primitive. Ex:

Integer obj = 5 (wrapper object) → auto → int x = 5 (primitive)

Where Primitive and wrapper objects are stored :

• Stack memory - Primitives like int, double are stored here. Fast, small, temporary.

• Heap memory - Wrapper objects like Integer, Double are stored here as full objects.