Basic concepts in OOP

Question 1

What is object oriented programming ?

Answer 1

A method of programming based on hierarchy of classes with well defined and cooperating objects
OR
A language model organized around objects
OR
A schematic paradigm for programming in which the linear concepts of procedures and tasks are replaced by the concepts of objects and message passing.

Question 2

What is an object ?

Answer 2

An object is an executable copy of a class.
OR
It can be referred to as a new instance

Question 3

What are the characteristics of objects ?

Answer 3

State

Behavior

Question 4

How do you create an object ?

Answer 4

Create a class
Create a constructor 
Create the object

Question 5

How does an object store its states

Answer 5

In fields

Question 6

How does an an object expose its behavior

Answer 6

through methods

Question 7

How do objects communicate?

Answer 7

through methods that operate on an objects internal state.

Question 8

What is a class?

Answer 8

A blueprint from which then individual objects can be created.
OR 
A class is a structure that defines the data and the methods to work on that data

Question 9

What is the syntax of class

Answer 9

class CLASSNAME{
// constructor( )
{ }
// Object 
}

Question 10

What is a package

Answer 10

A namespace that organizes a set of related classes and interfaces.

Question 11

What is an encapsulation

Answer 11

The concept that enables the hiding unnecessary details in classes and only providing a clear and simple interface for working with them.

Question 12

What is inheritance?

Answer 12

This is a concept in OOP that enables new objects to take on the properties of existing objects.

Question 13

What is a subclass/derived class?

Answer 13

A class that inherits from a superclass.

Question 14

What is the base or superclass?

Answer 14

A class that is used as the basis for inheritance.

Question 15

Example

Answer 15

class Student {
int studentID;
String emailAddress;
String name;
String sex;
Date D.O.B;
string course;
} 
class UndergraduateStudent extends Student{
String mentor;
string degreeCourse;
int numberOfMajors;

Question 16

What is abstraction?

Answer 16

Abstraction is the process of extracting common features from specific examples.
OR
Abstraction is a process of defining the essential concepts while ignoring the inessential details.

Question 17

What are the different types of abstraction?

Answer 17

Data Abstraction
Functional Abstraction
Object Abstraction

Question 18

What is polymorphism?

Answer 18

This is the ability to present the same interface differing underlying forms

Question 19

What are the two common types of polymorphism in OOP?

Answer 19

Method Overloading

Method overriding

Question 20

What is garbage collection?

Answer 20

This is a form of automatic memory management whereby the garbage collector attempts to reclaim garbage or memory occupied by the objects that are no longer in use by the program.

Question 21

What are variables?

Answer 21

This is a container that holds values that are used in a program.

Question 22

what are the types of variables in java?

Answer 22

Instance variables 
class variables 
local variable 
parameters

Question 23

What is an instance variable?

Answer 23

Non-static fields are also known as instance variables because their values are unique to each instance of a class (object)

Question 24

What is a class variable?

Answer 24

This is a field declared with the static modifier

Question 25

What is a local variable

Answer 25

These are variables declared within a method.

Question 26

What are parameters?

Answer 26

These are the variables found within the parenthesis.