Java Interview

Question 1

What is an ENUM class ?

Question 2

What is the JVM and how does it work ?

Answer 2

The Java Virtual Machine(abstract) is Platform Dependent. It takes BYTECODE and using a Just-In-Time Interpreter, generates MACHINE CODE for the underlying CPU to execute

Question 3

What is JAVA ?

Answer 3

Platform Independent Language. Object Oriented Programming Language. Portable - WORA

Question 4

What is JRE ?

Answer 4

Java Runtime Environment. JRE = JVM + compiled Java classes and Libraries in bytecode (.class files)

Question 5

What is JDK ?

Answer 5

Java Language + Java Compiler + Debugger + JRE

Question 6

What is OOPs ?

Answer 6

Object Oriented Programming (as opposed to Procedural)

Question 7

What are the four pillars of OOPS ?

Answer 7

Encapsulation
Abstraction
Inheritance
Polymorphism

Question 8

What is Encapsulation ?

Question 9

What is an Object ?

Answer 9

An Object is a representation of a real world entity. It has 3 aspects - state, behaviour and identity

Question 10

What is a Class ?

Answer 10

A blueprint for an object

Question 11

What is Data Abstraction

Answer 11

Implementation of Objects is hidden. The external Behaviour only is apparent. e.g. press pedal of Car - it slows down. how that is done is abstracted

Question 12

H