What is the difference between using objects and working with primitive data types?

In Java, primitive data types are such types as int, double, boolean, etc. They store values directly and are passed by value. Objects, on the other hand, are instances of classes stored in the heap, and variables contain references to these objects.

Main differences:

• Storage: primitives are stored in the stack (or at the declaration site), objects are stored in the heap.
• Passing: primitives are passed by value (a copy of the value), objects are passed by reference (a copy of the reference).
• Capabilities: objects can contain methods and state, primitives only hold values.

Example:

int a = 5;
int b = a; // copy of the value
b = 10;
// a remains 5

String s1 = new String("hello");
String s2 = s1; // copy of the reference
s2 = "world";
// s1 remains "hello" (String is immutable)

Thus, working with objects requires understanding reference semantics, while primitives involve values.