What is a composite datatype? What is a user-defined datatype?

Composite datatype:
A datatype that is made up of multiple values or other datatypes.
Examples in Java:

• Array → collection of same type of data.

• Class/Objects → bundle of variables + methods.

• String → technically an object that holds a sequence of characters.

int[] marks = {90, 85, 70}; // Array = composite datatype

User-defined datatype:
A datatype that is created by the programmer using classes, interfaces, or enums.
Example:

class Student {
    String name;
    int age;
}

Here, Student is a user-defined datatype.