What are main features of OOPS Java- JavaDoor

Table of Contents

Main Features of OOP (Object-Oriented Programming):

Encapsulation
Abstraction
Inheritance
Polymorphism
Method Overriding
Method Overloading
Classes and Objects

1. Encapsulation

Encapsulation means binding the data and methods that operate on that data into a single unit, and restricting outside access to it.

<code>javaCopyEdit<code>class Person {
    private String name; // private variable

    // Getter method
    public String getName() {
        return name;
    }

    // Setter method
    public void setName(String name) {
        this.name = name;
    }
}

public class Main {
    public static void main(String[] args) {
        Person person = new Person();
        person.setName("John");
        System.out.println(person.getName()); // Output: John
    }
}

2. Abstraction

Abstraction is the process of hiding implementation details and showing only the essential features.

javaCopyEditabstract class Animal {
    abstract void makeSound(); // Abstract method
}

class Dog extends Animal {
    void makeSound() {
        System.out.println("Bark");
    }
}

public class Main {
    public static void main(String[] args) {
        Animal dog = new Dog();
        dog.makeSound(); // Output: Bark
    }
}

3. Inheritance

Inheritance allows a class (child) to acquire properties and behavior (methods) of another class (parent).

javaCopyEditclass Animal {
    void eat() {
        System.out.println("This animal eats food.");
    }
}

class Dog extends Animal {
    void bark() {
        System.out.println("The dog barks.");
    }
}

public class Main {
    public static void main(String[] args) {
        Dog dog = new Dog();
        dog.eat();  // Output: This animal eats food.
        dog.bark(); // Output: The dog barks.
    }
}

4. Polymorphism

Polymorphism allows one interface to be used for a general class of actions.

javaCopyEditclass Animal {
    void makeSound() {
        System.out.println("Some sound");
    }
}

class Dog extends Animal {
    void makeSound() {
        System.out.println("Bark");
    }
}

class Cat extends Animal {
    void makeSound() {
        System.out.println("Meow");
    }
}

public class Main {
    public static void main(String[] args) {
        Animal myDog = new Dog();
        Animal myCat = new Cat();

        myDog.makeSound(); // Output: Bark
        myCat.makeSound(); // Output: Meow
    }
}

5. Method Overriding

Method overriding means redefining a method in the subclass that already exists in the parent class.

javaCopyEditclass Animal {
    void makeSound() {
        System.out.println("Some sound");
    }
}

class Dog extends Animal {
    @Override
    void makeSound() {
        System.out.println("Bark");
    }
}

public class Main {
    public static void main(String[] args) {
        Animal animal = new Dog();
        animal.makeSound(); // Output: Bark
    }
}

6. Method Overloading

Method overloading allows multiple methods with the same name but different parameters in a class.

javaCopyEditclass MathOperations {
    int add(int a, int b) {
        return a + b;
    }

    int add(int a, int b, int c) {
        return a + b + c;
    }
}

public class Main {
    public static void main(String[] args) {
        MathOperations math = new MathOperations();
        System.out.println(math.add(2, 3));     // Output: 5
        System.out.println(math.add(2, 3, 4));  // Output: 9
    }
}

7. Classes and Objects

A class is a blueprint for objects. An object is an instance of a class.

javaCopyEditclass Car {
    String model;
    int year;

    void displayInfo() {
        System.out.println("Model: " + model + ", Year: " + year);
    }
}

public class Main {
    public static void main(String[] args) {
        Car car = new Car();
        car.model = "Toyota";
        car.year = 2020;
        car.displayInfo(); // Output: Model: Toyota, Year: 2020
    }
}

What are main features of OOPS ?