Basics of OOP

Question 1

Object-oriented programming is

Answer 1

a paradigm based on the con-
cept of wrapping pieces of data, and behavior related to that
data, into special bundles called objects, which are construct-
ed from a set of “blueprints”, defined by a programmer, called
classes.

Question 2

Data stored inside the object’s fields is often referenced
as ____, and all the object’s methods define its _____.

Answer 2

Data stored inside the object’s fields is often referenced
as state, and all the object’s methods define its behavior.

Question 3

A parent class, is called a
____. Its children are ____.

Answer 3

A parent class, like the one we’ve just defined, is called a
superclass. Its children are subclasses.

Question 4

Subclasses inherit ____
and ___ from their parent, defining only ___ or ____ that differ

Answer 4

Subclasses inherit state
and behavior from their parent, defining only attributes or
behaviors that differ

Question 5

Assumingthatwehavearelatedbusinessrequirement,wecan
go even further and extract a more general class for all liv-
ing Organisms which will become a superclass for Animals
and Plants . Such a pyramid of classes is a

Answer 5

hierarchy. In such
a hierarchy, the Cat class inherits everything from both the
Animal and Organism classes.

Question 6

What can subclasses override from parent classes?

Answer 6

Subclasses can override the behavior of methods they inherit from parent classes.

Question 7

How can subclasses change the behavior of inherited methods?

Answer 7

Subclasses can either completely replace the default behavior or enhance it with extra features.

Question 8

Can subclasses enhance the default behavior of inherited methods?

Answer 8

es, they can enhance the default behavior with some extra stuff.

Question 9

Difference between Abstract Classes and Interfaces?

Answer 9

Abstract classes can have both abstract and concrete methods; whereas, interfaces can only have abstract methods.
An interface is a contract that specifies a set of methods that a class that is implementing must implement.

Question 10

Can Association have many-to-many relationship?

Answer 10

In can be represented as one-to-one, one-to-many, or many-to-many (aka cardinality).

Question 11

Code reuse

Answer 11

Using design patterns is one way to increase flexibility of software components and make them easier to reuse. However, this sometimes comes at the price of making the components
more complicated.

Question 12

Encapsulate What Varies

Answer 12

Identify the aspects of your application that vary and separate them from what stays the same.

Question 13

What should all products follow in the Factory Method pattern?

Answer 13

All products should follow the same interface, declaring methods that make sense for every product.

Question 14

What should the return type of the factory method match?

Answer 14

The return type of the factory method should match the common product interface.

Question 15

What should you replace product constructor references with in the creator’s code?

Answer 15

Replace them with calls to the factory method, extracting the product creation code into the factory method.

Question 16

What might you need to add to the factory method to control the type of returned product?

Answer 16

A temporary parameter.

Question 17

What can you do if the factory method has a large switch operator?

Answer 17

you can create subclasses for each product type and override the factory method in them.

Question 18

What can you do if there are too many product types to create subclasses for all of them?

Answer 18

Reuse the control parameter from the base class in subclasses to determine the product type.

Question 19

What should you do if the base factory method becomes empty after extractions?

Answer 19

What should you do if the base factory method becomes empty after extractions?

Question 20

What is an alternative to creating new subclasses for multiple product types?

Answer 20

Pass an argument to the factory method to control which product type is returned.

Question 21

Q: What is a benefit of the Factory Method pattern regarding coupling?

Answer 21

A: It avoids tight coupling between the creator and the concrete products.

Question 21

Q: How does the Factory Method pattern support the Single Responsibility Principle?

Answer 21

A: It moves product creation code into one place, making the code easier to support.

Question 22

Q: How does the Factory Method pattern align with the Open/Closed Principle?

Answer 22

A: It allows introducing new product types without breaking existing client code.

Question 23

Q: What is a potential downside of using the Factory Method pattern?

Answer 23

A: The code may become more complicated due to the introduction of many new subclasses.

Question 24

Q: When is the Factory Method pattern easiest to implement?

Answer 24

A: When introducing it into an existing hierarchy of creator classes.

Question 25

Q: How does the Factory Method pattern relate to Abstract Factory?

Answer 25

A: Abstract Factory classes are often based on a set of Factory Methods.

Question 26

Q: How can Factory Method and Iterator work together?

Answer 26

A: They allow collection subclasses to return different types of iterators compatible with the collections.

Question 27

Q: How does Prototype differ from Factory Method?

Answer 27

A: Prototype isn’t based on inheritance and requires complicated initialization, while Factory Method is based on inheritance and doesn’t require initialization.

Question 28

Q: What is the relationship between Factory Method and Template Method?

Answer 28

A: Factory Method is a specialization of Template Method and may serve as a step in a larger Template Method.