Design Pattern

Question 1

These are typical solutions to commonly occurring problems in software design. They are like pre-made blueprints that you can customize to solve a recurring design problem in your code.

Answer 1

Design Patterns

Question 2

This pertains to what the object has

Answer 2

Object Composition

Question 3

what the object is

Answer 3

object inheritance

Question 4

DRY

Answer 4

Don’t Repeat Yourself

Question 5

KISS

Answer 5

Keep It Simple Stupid

Question 6

YAGNI

Answer 6

You ain’t gonna need it

Question 7

Classes you create should have exactly one responsibility

Answer 7

Single Responsibility Principle (SRP)

Question 8

OPEN for extension, CLOSED for modification

extend, override, overload

Answer 8

Open/Closed Principle

Question 9

child classes or subclasses should be able to be used as substitute to parent class

if you replace an object of the parent class with an object of the subclass, the code should still work correctly

Answer 9

Liskov Substitution Principle

Question 10

clients should not be forced to depend on methods they do not use

clients: methods / classes that use the interface

should be narrow enough, that the client don’t implement the ones it does not need

Answer 10

Interface Segregation Principle

Question 11

High - level classes should not depend on low - level classes.

Both depend on abstractions.

Abstraction should not depend on details. Details depend on abstraction.

High - level classes: deals with overall functionality, directs low - level classes

Low - level classes: classes with specific details

Answer 11

Dependency Inversion Principle

Question 12

Handles the creation of objects

These patterns provide various object creation mechanisms, which increase flexibility and reuse of existing code.

Answer 12

Creational Design Patterns

Question 13

These patterns explain how to assemble objects and classes into larger structures while keeping these structures flexible and efficient.

uses interfaces to add functionality to objects

Answer 13

Structural Design Patterns

Question 14

These patterns are concerned with algorithms and the assignment of responsibilities between objects.

Answer 14

Behavioral Design patterns

Question 15

a creational design pattern that provides an interface for creating objects in a superclass, but allows subclasses to alter the type of objects that will be created.

Answer 15

Factory Method

Question 16

a creational design pattern that lets you produce families of related objects without specifying their concrete classes.

Answer 16

Abstract Factory

Question 17

a creational design pattern that lets you construct complex objects step by step. The pattern allows you to produce different types and representations of an object using the same construction code.

Answer 17

Builder

Question 18

a creational design pattern that lets you copy existing objects without making your code dependent on their classes.

Answer 18

Prototype

Question 19

a creational design pattern that lets you ensure that a class has only one instance, while providing a global access point to this instance.

Answer 19

Singleton

Question 20

is a structural design pattern that allows objects with incompatible interfaces to collaborate.

Answer 20

Adapter

Question 21

a structural design pattern that lets you split a large class or a set of closely related classes into two separate hierarchies—abstraction and implementation—which can be developed independently of each other.

Answer 21

Bridge

Question 22

a structural design pattern that lets you compose objects into tree structures and then work with these structures as if they were individual objects.

Answer 22

Composite

Question 23

a structural design pattern that lets you attach new behaviors to objects by placing these objects inside special wrapper objects that contain the behaviors.

Answer 23

Decorator

Question 24

a structural design pattern that provides a simplified interface to a library, a framework, or any other complex set of classes.

Answer 24

Facade

Question 25

a structural design pattern that lets you fit more objects into the available amount of RAM by sharing common parts of state between multiple objects instead of keeping all of the data in each object.

Answer 25

Flyweight

Question 26

a structural design pattern that lets you provide a substitute or placeholder for another object. A proxy controls access to the original object, allowing you to perform something either before or after the request gets through to the original object.

Answer 26

Proxy

Question 27

a behavioral design pattern that lets you pass requests along a chain of handlers. Upon receiving a request, each handler decides either to process the request or to pass it to the next handler in the chain.

Answer 27

Chain of Responsibility

Question 28

a behavioral design pattern that turns a request into a stand-alone object that contains all information about the request. This transformation lets you pass requests as a method arguments, delay or queue a request’s execution, and support undoable operations.

Answer 28

Command

Question 29

a behavioral design pattern that lets you traverse elements of a collection without exposing its underlying representation (list, stack, tree, etc.).

Answer 29

Iterator

Question 30

a behavioral design pattern that lets you reduce chaotic dependencies between objects. The pattern restricts direct communications between the objects and forces them to collaborate only via a mediator object.

Answer 30

Mediator

Question 31

a behavioral design pattern that lets you save and restore the previous state of an object without revealing the details of its implementation.

Answer 31

Memento

Question 32

a behavioral design pattern that lets you define a subscription mechanism to notify multiple objects about any events that happen to the object they’re observing.

Answer 32

Observer

Question 33

a behavioral design pattern that lets an object alter its behavior when its internal state changes. It appears as if the object changed its class.

Answer 33

State

Question 34

a behavioral design pattern that lets you define a family of algorithms, put each of them into a separate class, and make their objects interchangeable.

Answer 34

Strategy

Question 35

a behavioral design pattern that defines the skeleton of an algorithm in the superclass but lets subclasses override specific steps of the algorithm without changing its structure.

Answer 35

Template Method

Question 36

a behavioral design pattern that lets you separate algorithms from the objects on which they operate.

Answer 36

Visitor

Question 37

why prefer composition over inheritance

Answer 37

composition offers several advantages over inheritance, including greater flexibility, reduced complexity, and improved maintainability. It can also avoid problems associated with multiple inheritance, such as the “diamond problem.” While inheritance still has its place in object-oriented programming.