Sure! Let’s dive into Abstraction in Java.

What is Abstraction?

Abstraction is one of the core principles of Object-Oriented Programming (OOP), and it allows us to hide complex implementation details and show only the essential features of an object. This helps reduce complexity and allows focusing on higher-level concepts.

In Java, Abstraction is achieved using:

• Abstract Classes

• Interfaces

1. Abstract Class

An abstract class is a class that cannot be instantiated (i.e., you cannot create an object of an abstract class directly). It can have abstract methods (methods without a body) as well as regular methods (with a body).

Example of Abstract Class:

abstract class Animal {    // Abstract method (no body)    abstract void sound();    // Regular method    void sleep() {        System.out.println("This animal is sleeping.");    }}class Dog extends Animal {    // Providing implementation of abstract method    void sound() {        System.out.println("Bark");    }}public class Main {    public static void main(String[] args) {        Animal myDog = new Dog();  // Creating an object of Dog        myDog.sound();  // Calling abstract method        myDog.sleep();  // Calling regular method    }}

Output:

BarkThis animal is sleeping.

Key Points:

• An abstract class can have both abstract (no implementation) and non-abstract methods (with implementation).

• Subclasses of the abstract class must implement the abstract methods unless they are also abstract.

2. Interface

An interface is a contract that specifies the methods a class must implement. All methods in an interface are implicitly abstract (no body) until Java 8, where you can also define default methods with implementation.

Example of Interface:

interface Animal {    // Abstract method (no body)    void sound();    // Default method with a body (from Java 8)    default void sleep() {        System.out.println("This animal is sleeping.");    }}class Dog implements Animal {    // Providing implementation of abstract method    public void sound() {        System.out.println("Bark");    }}public class Main {    public static void main(String[] args) {        Animal myDog = new Dog();  // Creating an object of Dog        myDog.sound();  // Calling abstract method        myDog.sleep();  // Calling default method    }}

Output:

BarkThis animal is sleeping.

Key Points:

• An interface can only have abstract methods and static or default methods (from Java 8).

• A class that implements an interface must provide implementations for all abstract methods of the interface.

Why Use Abstraction?

• Simplifies complex systems: Users only interact with what they need, hiding the complexity.

• Encourages modular design: Code can be more flexible and maintainable.

• Provides better security: By restricting direct access to some parts of an object, abstraction helps keep certain details private.

Summary:

• Abstract Class: Can have both abstract and non-abstract methods. Used when classes share common behavior but also have some differences.

• Interface: A contract with only abstract methods (except default/static methods in Java 8+). Used to represent common behavior across unrelated classes.

Would you like a real-world example of abstraction in Java (e.g., for a bank system or vehicle system)? It can help make the concept even clearer! ?