JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD MCA JAVA PROGRAMMING Previous Question Paper (May - 2022 - R20)

The this keyword in Java is a reference variable that refers to the current object instance. It is primarily used to resolve ambiguity between instance variables and parameters with the same name, or to invoke other constructors within the same class.

Example:

class Student {
    String name;
    Student(String name) {
        this.name = name; // Resolves ambiguity between parameter and field
    }
}

Key uses include:

• Referencing the current class instance variable.
• Invoking current class constructor using
  this()
  .
• Passing the current object as a parameter to another method.
• Returning the current class instance from a method.

Procedural programming focuses on a step-by-step execution of functions or procedures, whereas Object-Oriented Programming (OOP) focuses on objects that encapsulate both data and behavior.

In procedural languages like C, the program is divided into functions, and data moves freely between them. In OOP languages like Java, the program is organized into objects, which are instances of classes. This allows for features like inheritance, where new classes can derive properties from existing ones, and polymorphism, which allows objects to be treated as instances of their parent class, significantly improving maintainability and scalability.