Quiz 1 - Encapsulation, Inheritance, and Polymorphism

Object-Oriented Programming

What does OOP stands for?

Encapsulation

The principle of pushing data(fields) and methods that operate on that data into a single unit (class), while restricting direct access to the data by using access modifiers like private and exposing controlled access through public getter and setter methods. This ensures data hiding, security, and better maintainability.​

Inheritance

An Object-Oriented Programming(OOP) concept where one class (child/subclass)acquires the properties and behaviors of another class(parent/superclass) using the extends keyword. This promotes code reusability, better organization, and allows polymorphism.​

Polymorphism

In Java it means “many forms” — it allows the same method or object to behave differently depending on the context, typically through method overloading (compile-time polymorphism) and method overriding (runtime polymorphism). It’s one of the core principles of Object-Oriented Programming (OOP) that enables flexibility and code reuse.​

Data Hiding

Class fields are declared private so they cannot be accessed directly from outside.​

Controlled Access

Public methods (getters and setters) are provided to read or modify private fields.

Data Hiding and Controlled Access

Key points of Encapsulation

Benefits of Encapsulation

- Protects data integrity by controlling how values are set.​

- Makes code easier to maintain and modify without breaking other parts.​

- Improves readability and usability.​

- Supports modular programming.​

Customization and Polymorphism

Key points of Inheritance

Superclass (Parent/Base Class)

The class whose features are inherited.​

Subclass (Child/Derived Class)

The class that inherits from the superclass.​

Customization

Subclass can add new fields/methods or override existing ones.​

Polymorphism

Enables writing flexible code where a parent reference can point to child objects.​

Single, Multilevel, Hierarchical, and Hybrid

Types of Inheritance

Single Inheritance

One class inherits from another.​

Multilevel Inheritance

A class inherits from a subclass (chain).​

Hierarchical Inhertiance

Multiple classes inherit from one superclass.​

Hybrid Inheritance

Combination of different types (not directly supported in Java due to ambiguity, but achievable via interfaces).​

Compile-time (Method Overloading) and Runtime (Method Overriding)

Key points of Polymorphism

Compile-time Polymorphism (Method Overloading)

- Multiple methods with the same name but different parameter lists.​

- Decided at compile time.​

Runtime Polymorphism (Method Overriding)

- A subclass provides a specific implementation of a method already defined in its superclass.​

- Decided at runtime based on the actual object type.​