What is the difference between primitive and reference types?

Primitive types store the actual data value, while reference types store a reference (memory address) to an object.

Primitive types:

• occupy a fixed amount of memory.
• are passed by value (the value itself is copied).
• are not objects and do not have methods.
• are used for simple data (numbers, characters, boolean values).

// Primitive types in Java
int count = 10; // stores the value 10
boolean isValid = true; // stores the value true

Reference types:

• occupy varying amounts of memory depending on the object.
• are passed by reference (the address of the object is copied).
• are objects and have methods.
• are used for complex data (objects, arrays, strings).

// Reference types in Java
String message = "Hello"; // message stores a reference to a string object in memory
Integer number = 20; // Integer is a wrapper class for the primitive type int, a reference type

Comparison:

Attribute	Primitive types	Reference types
Storage	Value	Reference (address)
Passing	By value	By reference
Memory size	Fixed	Variable
OOP	Not objects	Objects
Example	int, boolean, char	String, Object, Array