Interview question

What are Object-Oriented Programming (OOP) principles? Object-Oriented Programming (OOP) के सिद्धांत क्या हैं?

Answer

OOP is a programming paradigm based on objects and classes. It follows four main principles: Encapsulation, Inheritance, Polymorphism, and Abstraction.

Principle	Description	Example
Encapsulation	Bundling data and methods, hiding implementation details	Private variables with getter/setter
Inheritance	A class inherits properties from another class	Child extends Parent
Polymorphism	Objects can take many forms, same method different behavior	Method overriding, overloading
Abstraction	Hiding complex details, showing only essential features	Abstract classes, interfaces

// OOP Example
public class Animal {
    // Encapsulation - private data
    private String name;
    private int age;
    
    // Constructor
    public Animal(String name, int age) {
        this.name = name;
        this.age = age;
    }
    
    // Method
    public void sound() {
        System.out.println('Making sound');
    }
}

// Inheritance - Dog inherits from Animal
public class Dog extends Animal {
    // Polymorphism - overriding parent method
    @Override
    public void sound() {
        System.out.println('Dog barks');
    }
}

// Usage
Animal dog = new Dog('Buddy', 3);
dog.sound();  // Prints: Dog barks

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