OOP Programming Concepts

Questions and Answers

What aspect of an object in object-oriented programming defines what the object can do?

State

Properties

Methods (correct)

Identity

Which of the following statements about constructors is true?

The name of a constructor must differ from the class name. (correct)

Constructors are invoked using the delete operator.

Constructors cannot accept parameters.

Constructors can have a return type.

What is a no-arg constructor?

A constructor that has no parameters. (correct)

A constructor that cannot be invoked.

A constructor that initializes multiple objects.

A constructor that takes one parameter.

Which line of code correctly creates a new object of the Circle class?

Circle newCircle = new Circle(); Signup and view all the answers

What is implicitly defined in a class if no constructors are explicitly declared?

No-arg constructor Signup and view all the answers

How is an object's state characterized in object-oriented programming?

By its unique properties and current values Signup and view all the answers

What does the reference variable do in object-oriented programming?

It references an object in memory. Signup and view all the answers

Which statement accurately describes the identity of an object?

It distinguishes one object from another. Signup and view all the answers

What is the purpose of a constructor in a class?

To initialize objects of the class. Signup and view all the answers

Which of the following is NOT a characteristic of an object?

Static structure Signup and view all the answers

Study Notes

Object-Oriented Programming (OOP) Concepts

OOP involves programming with objects, representing real-world entities.
Examples of objects include a student, desk, circle, button, or loan.
An object has three core features: unique identity, state, and behaviors.
The state consists of data fields (properties) holding current values.
The behavior of an object is demonstrated through methods.

Understanding Classes

Classes define a blueprint for creating objects of the same type.
In Java, classes employ variables for data fields and methods for behaviors.
Classes include constructors, special methods for creating and initializing objects.

Constructors and Their Role

A no-arg constructor is a constructor without parameters.
Constructors share the name with their class and do not have a return type.
They are invoked using the new operator to create objects.
Example of object instantiation: new Circle(); or new Circle(5.0);

Default Constructors

If no constructors are defined, a default constructor is automatically provided.
The default constructor is a no-arg constructor with an empty body.

Declaring Object Reference Variables

Object reference variables enable access to objects in Java.
Declaration syntax: ClassName objectRefVar;
Example: Circle myCircle;

Description

This quiz explores the fundamental concepts of Object-Oriented Programming (OOP). You will learn about the characteristics of objects, including identity, state, and behaviors. Test your understanding of how these concepts are applied in programming.