Pillars of OOP

Question 1

Object-oriented programming is based on four pillars, concepts that

Answer 1

differentiate it from other programming paradigms(system of concepts)

Question 2

4 pillars

Answer 2

Abstraction
Encapsulation
Inheritance
Polymorphism

Question 3

Abstraction

Answer 3

model of a real-world object or phenomenon,
limited to a specific context, which represents all details relevant to this context with high accuracy and omits all the rest.

Question 4

each object has
an interface —

Answer 4

a public part of an object, open to interactions
with other objects

Question 5

Encapsulation is

Answer 5

the ability of an object to hide parts of its
state and behaviors from other objects, exposing only a limit-
ed interface to the rest of the program.

Question 6

To encapsulate something means to make it

Answer 6

private and thus
accessible only from within of the methods of its own class.

Question 7

There’s a little bit less restrictive than private mode called

Answer 7

protected that
makes a member of a class available to subclasses as well.

Question 8

the interface mechanism (usually declared with the
interface or protocol keyword) lets you

Answer 8

define contracts of
interaction between objects.

Question 9

Inheritance is

Answer 9

the ability to build new classes on top of exist-
ing ones.

Question 10

he main benefit of inheritance is

Answer 10

code reuse.

Question 11

The consequence(result) of using inheritance is that

Answer 11

subclasses have
the same interface as their parent class. You can’t hide a
method in a subclass if it was declared in the superclass. You
must also implement all abstract methods, even if they don’t
make sense for your subclass.

Question 12

In most programming languages a subclass can extend only

Answer 12

one superclass.

Question 13

any class can implement
several

Answer 13

interfaces at the same time

Question 14

if a superclass implements an interface,

Answer 14

all of its subclasses
must also implement it.

Question 15

Polymorphism is

Answer 15

the ability of a program to detect the real class of an object and call its implementation even when its real
type is unknown in the current context.

Question 16

You can also think of polymorphism as the ability of an object
to

Answer 16

“pretend” to be something else, usually a class it extends or
an interface it implements.