Question 1

What is encapsulation?

Accepted Answer

Bundling data and methods together while hiding internal details. Encapsulation bundles data (attributes) and behavior (methods) into a class and restricts direct access to internal state. Achieved via private/protected access modifiers.

Question 2

What is inheritance?

Accepted Answer

A mechanism where a child class acquires properties and behavior of a parent class. Inheritance allows a class (child/subclass) to reuse and extend another class's (parent/superclass) code. Promotes code reuse and establishes an IS-A relationship.

Question 3

What is runtime polymorphism?

Accepted Answer

The correct method is determined at runtime through method overriding. Runtime polymorphism (dynamic dispatch) occurs with method overriding. The JVM/runtime determines which overridden method to call based on the actual object type.

Question 4

What is abstraction in OOP?

Accepted Answer

Hiding complex implementation and showing only essential features. Abstraction simplifies complex reality by modeling classes appropriate to the problem. In Java/C++: abstract classes and interfaces provide abstraction.

Question 5

What is the difference between an abstract class and an interface (in Java)?

Accepted Answer

Abstract class can have method implementations; interface (pre-Java 8) cannot. Abstract class can have constructors, state, and both abstract and concrete methods. Interface has no state, all methods are abstract (before Java 8 default methods).

OOP Concepts MCQ Quiz

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