Java Object-Oriented Programming (OOP)

Java is an object-oriented programming (OOP) language, which means it emphasizes the use of objects to model and manipulate data and behavior. Here's a concise overview of Java's OOP concepts:

Classes and Objects:

• A class is a blueprint for creating objects, defining their properties (attributes) and behaviors (methods).
• An object is an instance of a class, representing a specific entity in a program.
• Example

class Car {
    String brand;
    int year;

    void drive() {
        System.out.println("Driving the " + brand);
    }
}

// Creating objects of the class
Car myCar = new Car();
myCar.brand = "Toyota";
myCar.year = 2020;

Encapsulation:

• Encapsulation refers to the bundling of data (attributes) and methods that operate on the data within a class, preventing direct access from outside the class.
• Access to the data is controlled through methods, known as accessors and mutators (getters and setters)
• Example

class Student {
    private String name;
    private int age;

    // Getter and setter methods
    public String getName() {
        return name;
    }

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

    // Other methods...
}

Inheritance:

• Inheritance allows a class (subclass) to inherit properties and behaviors from another class (superclass).
• Subclasses can extend the functionality of their superclass and override inherited methods.
• Example

class Animal {
    void eat() {
        System.out.println("Animal is eating");
    }
}

class Dog extends Animal {
    void bark() {
        System.out.println("Dog is barking");
    }
}

Polymorphism:

• Polymorphism allows objects of different classes to be treated as objects of a common superclass.
• It enables methods to behave differently based on the object they are invoked on, facilitating code reuse and flexibility.
• Example

class Animal {
    void makeSound() {
        System.out.println("Animal makes a sound");
    }
}

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

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

Abstraction:

• Abstraction refers to the process of hiding complex implementation details and exposing only the essential features of an object.
• Abstract classes and interfaces provide a way to achieve abstraction in Java.
• Example

abstract class Shape {
    abstract void draw();
}

class Circle extends Shape {
    void draw() {
        System.out.println("Drawing a circle");
    }
}

class Rectangle extends Shape {
    void draw() {
        System.out.println("Drawing a rectangle");
    }
}

 

Summary

Java's OOP features promote modularity, code reuse, and maintainability, making it a popular choice for building robust and scalable software systems. Understanding OOP concepts is essential for developing effective Java applications.