JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II Year OBJECT ORIENTED PROGRAMMING THROUGH JAVA Previous Question Paper (March - 2021 - R16)

Java is a robust, object-oriented language designed for portability and security. Its key features include:

• Simple: Java eliminates complex features like explicit pointers and operator overloading, making it easier to learn and maintain.
• Object-Oriented: Everything in Java is an object, following principles like encapsulation, inheritance, polymorphism, and abstraction.
• Platform Independent: Java code is compiled into bytecode, which runs on any machine equipped with a Java Virtual Machine (JVM), adhering to the 'Write Once, Run Anywhere' (WORA) principle.
• Secure: Java provides a secure environment by avoiding explicit memory management and using a sandbox model for executing untrusted code.
• Robust: It emphasizes early error checking through strong type-checking and provides an effective exception handling mechanism.
• Multithreaded: Java supports concurrent execution of multiple threads, allowing developers to build interactive and responsive applications.
• Distributed: It facilitates the development of applications that can span across multiple machines over a network using RMI and EJB.

Inheritance allows a class to acquire the properties and behaviors of another. Java supports the following forms:

• Single Inheritance: A subclass inherits from one superclass.
  Example: class B extends A {}
• Multilevel Inheritance: A class inherits from a derived class, creating a chain.
  Example: class C extends B {} where B extends A.
• Hierarchical Inheritance: Multiple subclasses inherit from a single superclass.
  Example: class B extends A {} and class C extends A {}.
• Multiple Inheritance (via Interfaces): Java does not support multiple inheritance with classes to avoid ambiguity (the Diamond Problem), but it achieves this through interfaces.
  Example: class C implements A, B {}.

Note: Hybrid inheritance, a combination of the above, is also supported in Java only through the use of interfaces.