What is encapsulation, and why is it important?<\/strong><\/li>\n<\/ol>\n\n\n\nEncapsulation restricts direct access to certain object properties by using access modifiers like private, protected, and public. It improves security and prevents unintended modifications. <\/p>\n\n\n\n
For example, in Java:<\/strong><\/p>\n\n\n\nclass BankAccount {<\/p>\n\n\n\n
private double balance;<\/p>\n\n\n\n
public void deposit(double amount) { balance += amount; }<\/p>\n\n\n\n
public double getBalance() { return balance; }<\/p>\n\n\n\n
}<\/p>\n\n\n\n
Here, balance is private, so it can\u2019t be accessed directly. This prevents unauthorized modifications.<\/p>\n\n\n\n
\n- What is the difference between compile-time and runtime polymorphism?<\/strong><\/li>\n<\/ol>\n\n\n\n
This is one of OOPs most asked interview questions. <\/p>\n\n\n\n
Compile-time polymorphism occurs when the method to be called is determined at compile time (method overloading). Runtime polymorphism happens when the method to be executed is determined at runtime (method overriding).<\/p>\n\n\n\n
<\/span>Object Oriented Concepts Interview Questions<\/span><\/h2>\n\n\n\nHere is a list of common Object Oriented Programming concepts interview questions and answers:<\/p>\n\n\n\n
\n- What is abstraction? How does it help in OOP?<\/strong><\/li>\n<\/ol>\n\n\n\n
Abstraction hides unnecessary details while exposing only the relevant features of an object. It reduces complexity by allowing interaction with an object without knowing its inner workings. In Java, abstraction is implemented using abstract classes and interfaces.<\/p>\n\n\n\n
\n- How is inheritance implemented in OOP? Give an example.<\/strong><\/li>\n<\/ol>\n\n\n\n
Inheritance allows a class to acquire properties and methods from another class. In Java, it is implemented using the extends keyword.<\/p>\n\n\n\n
class Vehicle {<\/p>\n\n\n\n
String brand = “Ford”;<\/p>\n\n\n\n
}<\/p>\n\n\n\n
class Car extends Vehicle {<\/p>\n\n\n\n
int speed = 120;<\/p>\n\n\n\n
}<\/p>\n\n\n\n
Here, Car inherits the brand property from Vehicle, making the code reusable and reducing duplication.<\/p>\n\n\n\n
\n- What is method overloading? How is it different from method overriding?<\/strong><\/li>\n<\/ol>\n\n\n\n
Method overloading allows multiple methods in the same class to have the same name but different parameters. Method overriding occurs when a subclass provides a specific implementation of a method already defined in the parent class. Overloading happens at compile-time, while overriding happens at runtime.<\/p>\n\n\n\n
\n- What is an interface, and how does it differ from an abstract class?<\/strong><\/li>\n<\/ol>\n\n\n\n
An interface defines a contract that classes must implement. It only contains method declarations (without implementation), whereas an abstract class can have both abstract and concrete methods.<\/p>\n\n\n\n
\n- What is the purpose of constructors in OOP?<\/strong><\/li>\n<\/ol>\n\n\n\n
You might also come across OOPs concepts interview questions like this one. <\/p>\n\n\n\n
A constructor initializes an object when it is created. It is automatically called when an instance of a class is made. <\/p>\n\n\n\n
Example:<\/strong><\/p>\n\n\n\nclass Person {<\/p>\n\n\n\n
String name;<\/p>\n\n\n\n
Person(String n) { name = n; }<\/p>\n\n\n\n
}<\/p>\n\n\n\n
When Person p = new Person(“John”); is executed, “John” is assigned to name automatically.<\/p>\n\n\n\n
Note:<\/strong> Knowing OOPs concepts for interview like encapsulation, inheritance, polymorphism, and abstraction can help you answer questions easily.<\/p>\n\n\n\n