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In Java, abstraction helps us hide unnecessary details and show only what is important.

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It makes programs easier to understand, maintain, and extend.

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One of the main ways Java supports abstraction is through abstract classes and interfaces.

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Abstract classes represent concepts that cannot be created directly.

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For example, think of a general idea like a vehicle.

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You cannot create a generic vehicle, but you can create a car or bike.

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That is why an abstract class cannot be instantiated.

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Abstract classes allow you to write common code while still forcing some methods to be implemented

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by subclasses. Here, every vehicle must define how it drives, but they all share the ability to

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store a model name. Abstraction ensures cleaner structure. Shared behavior across related classes,

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hiding complex implementation details. This prepares us to explore deeper differences between

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abstract classes and interfaces. For example, a trucker-bite class can extend vehicle and provide

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their own version of drive. Abstract classes also allow instance variables, constructors,

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protected data. These features make them useful when multiple subclasses share state.

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Interfaces define a contract. They specify what a class must do without specifying how it is done.

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Before Java 8, interfaces could only have abstract methods, but now they can also include

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default methods. Static methods. This allows interfaces to evolve without breaking old code.

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Any class that implements driveable must define how it drives, but it automatically gains the

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honk behavior. Interfaces are also key for multiple inheritance of type. A class can implement

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multiple interfaces, allowing flexible and modular designs. Interfaces are best used when no shared

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state is required. Only method signatures need to be defined. Multiple unrelated classes need

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similar capabilities. Use an abstract class when multiple classes share common code. You need

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shared variables or state. A base class defines common behavior. Use an interface when you want

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a strict contract. Multiple classes need the same capabilities. Multiple inheritance is required.

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In this session, we learned what abstract classes are and why they cannot be instantiated.

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How interfaces act as contracts for behavior. How Java 8 introduced default and static methods

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in interfaces. How to choose between an abstract class and an interface.

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Abstraction through abstract classes in interfaces allows Java programs to be flexible,

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organized, and easier to maintain. Mastering these concepts prepares students for more advanced

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OOP techniques and real-world software development.