WEBVTT

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In this lesson, we will refresh the foundational ideas of object-oriented programming,

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inheritance, encapsulation, and polymorphism.

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These concepts form the base of Java programming and help us write cleaner, reusable,

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and structured code. Let's begin with inheritance refresher.

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In Java, a class can extend another class and reuse its properties and methods.

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This is known as single inheritance.

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For example, here the dog class inherits from animal.

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This makes our code reusable and easier to maintain. We also recall the difference between

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public and private members. Public members can be accessed anywhere, while private members are

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accessible only inside the same class. This leads us to our next concept, encapsulation.

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Incapsulation means protecting data by keeping variables private and accessing them through

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getters and setters. This helps maintain class invariance and prevents accidental misuse of data.

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Example, here the age variable is hidden and we control how it is set. This is also called

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data hiding. Incapsulation ensures the object always stays in a valid state. Polymorphism simply

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means one action, many forms. There are two main types, method overloading, same method name,

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different parameters, method overriding, same method name and parameters, but implemented

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differently in subclasses. Java decides at runtime which version of the method to run.

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This is runtime polymorphism. Polymorphic references allow us to write general code

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that works with multiple object types. In this session, we reviewed how Java uses single

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inheritance. Why encapsulation protects data? How polymorphism allows flexibility and cleaner

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code? And how small hands-on exercises can help reinforce these ideas? These OOP principles

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form the backbone of advanced Java programming and help students write powerful, organized,

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and efficient programs.