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WithoutBook LIVE Mock Interviews OOPs Related interview subjects: 74

Interview Questions and Answers

Know the top OOPs interview questions and answers for freshers and experienced candidates to prepare for job interviews.

Total 30 questions Interview Questions and Answers

The Best LIVE Mock Interview - You should go through before interview

Know the top OOPs interview questions and answers for freshers and experienced candidates to prepare for job interviews.

Interview Questions and Answers

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Intermediate / 1 to 5 years experienced level questions & answers

Ques 1

Explain the concept of encapsulation.

Encapsulation is the bundling of data and methods that operate on that data into a single unit known as a class. It restricts access to some of the object's components.
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Ques 3

Explain the concept of method overloading.

Method overloading is a feature in OOP where a class can have multiple methods with the same name but with different parameter types or a different number of parameters.

Example:

class MathOperations {
  add(a, b) {
    return a + b;
  }
  add(a, b, c) {
    return a + b + c;
  }
}
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Ques 4

What is an interface in OOP?

An interface in OOP defines a contract for classes, specifying a set of methods that a class must implement. It allows for achieving multiple inheritance in languages that don't support it directly.

Example:

interface Printable {
  print();
}
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Ques 5

Explain the concept of method overriding.

Method overriding occurs when a subclass provides a specific implementation for a method that is already defined in its superclass. It allows a subclass to provide a specialized version of a method.

Example:

class Animal {
  speak() {
    console.log('Animal speaks');
  }
}
class Dog extends Animal {
  speak() {
    console.log('Dog barks');
  }
}
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Ques 6

What is a destructor?

A destructor is a method that is called when an object is about to be destroyed. In many programming languages, like C++, it is used to release resources held by the object.

Example:

class MyClass {
  destructor() {
    // clean up resources
  }
}
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Ques 7

What is a virtual function?

A virtual function is a function in a base class that is declared using the 'virtual' keyword and can be overridden by a derived class. It enables dynamic method binding and polymorphism.

Example:

class Shape {
  virtual calculateArea() = 0;
}
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Ques 8

What is an abstract method?

An abstract method is a method declared in an abstract class or an interface that has no implementation in the base class. Subclasses must provide an implementation for abstract methods.

Example:

abstract class Printer {
  abstract print();
}
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Ques 9

Explain the term 'constructor chaining'.

Constructor chaining refers to the process of calling one constructor from another in the same class or a superclass. It allows for reusing code and initializing objects more efficiently.

Example:

class Vehicle {
  constructor(make) {
    this.make = make;
  }
}
class Car extends Vehicle {
  constructor(make, model) {
    super(make);
    this.model = model;
  }
}
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Ques 10

What is the purpose of the 'final' keyword?

In OOP, the 'final' keyword can be applied to classes, methods, or variables. It indicates that a class cannot be extended, a method cannot be overridden, or a variable cannot be reassigned.

Example:

final class MyFinalClass {
  // class content
}
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Ques 11

Explain the concept of method hiding.

Method hiding occurs when a subclass provides a static method with the same signature as a static method in its superclass. It does not override the method but hides it.

Example:

class Parent {
  static show() {
    console.log('Static method in Parent');
  }
}
class Child extends Parent {
  static show() {
    console.log('Static method in Child');
  }
}
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Ques 12

What is an abstract class in C#?

In C#, an abstract class is a class that cannot be instantiated and may contain abstract methods. It is used to provide a common base for related classes and enforce a certain structure on derived classes.

Example:

abstract class Shape {
  public abstract void Draw();
}
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Ques 13

Explain the 'is-a' and 'has-a' relationships in OOP.

'is-a' relationship represents inheritance, where a class is a specialized version of another class. 'has-a' relationship represents composition, where a class contains an instance of another class as a member.
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