Test your OOPs skills with simple questions on classes, objects, and inheritance. Great for interviews and coding practice.

OOPs Practice Test Online

Class is a runtime instance; object is a blueprint

Objects define behavior; classes define data

Class is a blueprint; object is an instance

Which best describes the difference between class and object?

Hiding internal state and requiring all interaction through methods

What best defines encapsulation in object-oriented programming?

To hide implementation details while exposing functionality

What is the purpose of abstraction in OOP?

Overloading is compile-time; overriding is runtime polymorphism

Which statement correctly describes the difference between method overloading and method overriding?

Composition implies ownership; aggregation implies association

Aggregation implies strong lifecycle coupling

Composition allows null references, aggregation doesn’t

How does aggregation differ from composition?

To provide a common template for child classes

To implement multiple unrelated behaviors

Why would a developer use an abstract class?

What is the ideal goal regarding cohesion and coupling in OOP?

Inheritance, because it reduces code duplication

Inheritance, because it's easier to understand

Composition, because it tightly couples objects

Composition, because it promotes flexibility and reuse

Which is generally preferred in large systems and why?

What is the main purpose of a constructor in a class?

What is one major benefit of using interfaces?

Ambiguity due to multiple inheritance from a common base class

Overloading a constructor with too many parameters

What is typically the final step in an object’s lifecycle?

Allows multiple objects to inherit the same class

Allows objects to be treated as instances of their parent class

What is the key advantage of polymorphism?

Shallow copy clones all nested objects recursively

Deep copy clones all referenced objects recursively

Which statement is true about shallow vs deep copy?

Which of the following are valid object-oriented design patterns?

A child class should override all methods

Child class must call super in constructor

Child classes must be substitutable for parent classes

What does the Liskov Substitution Principle ensure?

Which OOP concept helps represent 'A car **is a** vehicle' in a real-world model?

When it doesn’t depend on object instance

Open for extension, but closed for modification

According to the Open/Closed Principle, software entities should be:

When a constructor calls another constructor

When constructor calls superclass destructors

When all objects are constructed in a loop