JNTU B.Tech IV JAVA PROGRAMMING Previous Question Paper (February/March-2022 - R18)

Object-Oriented Programming (OOP) is a paradigm based on the concept of objects, which contain data and code. Its primary features include:

• Classes and Objects: A class is a blueprint for creating objects, while an object is an instance of a class that encapsulates state and behavior.
• Encapsulation: The bundling of data (variables) and methods that operate on the data into a single unit, restricting direct access to some components to protect internal state.
• Abstraction: Hiding complex implementation details and showing only the necessary features of an object to the user.
• Inheritance: A mechanism where a new class derives properties and behaviors from an existing class, promoting code reusability.
• Polymorphism: The ability of an object or method to take on multiple forms, typically achieved through method overloading (compile-time) and method overriding (runtime).

A constructor is a special member method that is invoked automatically when an object of a class is created. It has the same name as the class and no return type.

class Student {
    String name;
    int id;

    // Default Constructor
    Student() {
        name = "Unknown";
        id = 0;
    }

    // Parameterized Constructor
    Student(String n, int i) {
        name = n;
        id = i;
    }

    void display() {
        System.out.println("Name: " + name + ", ID: " + id);
    }
}

public class Main {
    public static void main(String[] args) {
        Student s1 = new Student();
        Student s2 = new Student("Alice", 101);
        s1.display();
        s2.display();
    }
}