Chapter 2: Object-Oriented Programming Concepts

Access Modifiers (public, private, protected)

Keywords used in object-oriented programming languages to set the accessibility of classes, methods, and other members. Example: "The 'public' access modifier allows other classes to access the method."

Encapsulation

The bundling of data and methods that operate on the data within a single unit, such as a class. It restricts direct access to some of an object's components and enhances data security. Example: "Encapsulation ensures that sensitive data is hidden from outside classes."

Abstraction

The concept of hiding the complex implementation details of a system and exposing only the necessary parts. Example: "Abstraction allows developers to work with objects at a high level without needing to understand all the intricacies of their internal workings."

Inheritance

The mechanism by which one class can inherit fields and methods from another class. Example: "A class that inherits from another class is called a subclass."

What is polymorphism in Java? a) The ability of a single method to perform different tasks b) The process of one class inheriting fields and methods from another class c) The use of methods with the same name but different parameters d) The concept of hiding the complex implementation details of a system

a) The ability of a single method to perform different tasks Explanation: Polymorphism in Java allows a single method to operate differently based on the object it is acting upon, often implemented through method overloading and overriding.

Which of the following best describes encapsulation in Java? a) Allowing a class to inherit properties from another class b) Binding data and methods into a single unit while restricting direct access c) Enabling multiple methods with the same name in a class d) Defining multiple classes within the same file

b) Binding data and methods into a single unit while restricting direct access Explanation: Encapsulation ensures that data is protected by restricting direct access and providing controlled access via methods.

What is the purpose of inheritance in Java? a) To hide complex implementation details b) To provide controlled access to class members c) To allow one class to inherit fields and methods from another class d) To enable objects to be treated as instances of their parent class

c) To allow one class to inherit fields and methods from another class Explanation: Inheritance enables a class to derive properties and behaviors from another class, promoting code reuse and establishing a parent-child relationship between classes.

Which access modifier allows other classes to access a method? a) private b) protected c) default (package-private) d) public

d) public Explanation: The 'public' access modifier allows a method or variable to be accessed by any other class.

Polymorphism

Allows objects to be treated as instances of their parent class, enabling a single interface to represent different underlying forms (method overloading and overriding). Example: "Polymorphism allows a single method to perform different tasks based on the object it is acting upon."