JNTU MCA 2022 JAVA PROGRAMMING Previous Question Paper (October/November - 2022 - R20)

Object-Oriented Programming (OOP) is a paradigm based on the concept of objects which contain data in the form of fields and code in the form of methods. The core concepts are:

1. Class: A blueprint or template that defines the properties and behaviors of objects.
2. Object: An instance of a class with a specific state and behavior.
3. Encapsulation: The mechanism of wrapping data and code together as a single unit and restricting direct access to some of an object's components.
4. Abstraction: Hiding complex implementation details and showing only the essential features of an object.
5. Inheritance: A mechanism where one class acquires the properties and behaviors of another class, promoting code reusability.
6. Polymorphism: The ability of an object or method to take on many forms, typically achieved through method overloading and overriding.

In Java, the scope and lifetime of a variable depend on its declaration:

1. Instance Variables: Declared inside a class but outside any method. Their scope is the entire class, and their lifetime is tied to the object; they are created when an object is instantiated and destroyed when the object is garbage collected.
2. Static (Class) Variables: Declared with the static keyword. Their scope is the class, and they exist for the entire duration of the program execution, shared by all instances of the class.
3. Local Variables: Declared inside a method, constructor, or block. Their scope is limited to the block in which they are defined. Their lifetime begins when the block is entered and ends when the block is exited.
4. Method Parameters: Act as local variables within the method. Their scope is the method body, and they are destroyed once the method execution completes.