Computer Knowledge

Object-Oriented Programming

2,686 Questions

Object-oriented programming questions test core computer science concepts like classes, inheritance, polymorphism, and encapsulation. The focus includes Java program structures, method overloading, and memory allocation for objects. This topic is essential for technical sections in various recruitment tests.

Java class definitionsMethod overriding rulesPolymorphism conceptsGeneric type parametersMemory allocation in objects

Object-Oriented Programming Questions

Multiple choice

Which of the following .NET cryptographic classes represents the abstract base class from which all implementations of asymmetric signature formatters derive?

  1. AsymmetricSignatureDeformatter

  2. AsymmetricSignatureFormatter

  3. DSASignatureFormatter

  4. AsymmetricKeyExchangeFormatter

  5. RandomNumberGenerator
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This .NET cryptographic class represents the abstract the base class from which all implementations of asymmetric signature formatters derive.

Multiple choice

Does a child class inherit superclass constructor?

  1. Yes

  2. No
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Constructors are NOT inherited in Java - each class must define its own constructors. A child class can CALL the parent constructor using super(), but it does not inherit it. The child class must have its own constructor, even if it only calls super().

Multiple choice

A manager class extends employee class. To invoke the constructor of parent class, user has to invoke …………. method.

  1. employee.super();

  2. super();

  3. manager.super();

  4. no method will require
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

To invoke a parent class constructor from a child class constructor, use super() as the first statement. Option A (employee.super()) and C (manager.super()) are invalid syntax. The super() keyword alone calls the parent constructor - it's a language keyword, not a method on any object.

Multiple choice

Variables labeled …………….. are created when class is loaded and continue to exist for as long as the class is loaded.

  1. final

  2. static

  3. both (1) and (2)

  4. none of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Static variables are created when the class is loaded and persist as long as the class remains loaded. They're shared across all instances. Final variables are constants but can be instance or static. Only static has the class-lifetime behavior described in the question.