Design Patterns

Question 1

Creational Design Patterns

Answer 1

• all about creating objects while hiding creation logic

- flexibility to decide which objects to create for a use case

Question 2

Abstract Factory

Answer 2

Creates an instance of several families of classes

Question 3

Builder

Answer 3

Separates object construction from its representation

Question 4

Factory Method

Answer 4

Creates an instance of several derived classes

Question 5

Object Pool

Answer 5

Avoid expensive acquisition and release of resources by recycling objects that are no longer in use

Question 6

Prototype

Answer 6

A fully initialized instance to be copied or cloned

Question 7

Singleton

Answer 7

A class of which only a single instance can exist

Question 8

Structural Design Patterns

Answer 8

• all about class composition

- inheritance is used to compose interfaces and get new functionality

Question 9

Adapter

Answer 9

Match interfaces of different classes

Question 10

Bridge

Answer 10

Separates an object’s interface from its implementation

Question 11

Composite

Answer 11

A tree structure of simple and composite objects

Question 12

Decorator

Answer 12

Add responsibilities to objects dynamically

Question 13

Facade

Answer 13

A single class that represents an entire subsystem

Question 14

Flyweight

Answer 14

A fine-grained instance used for efficient sharing

Question 15

Private Class Data

Answer 15

Restricts accessor/mutator access

Question 16

Proxy

Answer 16

An object representing another object

Question 17

Behavioral Design Patterns

Answer 17

all about class communication

Question 18

Chain of responsibility

Answer 18

A way of passing a request between a chain of objects

Question 19

Command

Answer 19

Encapsulate a command request as an object

Question 20

Interpreter

Answer 20

A way to include language elements in a program

Question 21

Iterator

Answer 21

Sequentially access the elements of a collection

Question 22

Mediator

Answer 22

Defines simplified communication between classes

Question 23

Memento

Answer 23

Capture and restore an object’s internal state

Question 24

Null Object

Answer 24

Designed to act as a default value of an object

Question 25

Observer

Answer 25

A way of notifying change to a number of classes

Question 26

State

Answer 26

Alter an object’s behavior when its state changes

Question 27

Strategy

Answer 27

Encapsulates an algorithm inside a class

Question 28

Template method

Answer 28

Defer the exact steps of an algorithm to a subclass

Question 29

Visitor

Answer 29

Defines a new operation to a class without change

Question 30

GoF

Answer 30

Gang of Four, solidified the concept of Design Patterns

Question 31

GoF Principle:

Program to an ____ not an implementation.

Answer 31

interface

Question 32

GoF Principle:

Program to an interface, not an _____.

Answer 32

implementation

Question 33

GoF Principle:

Favor object _____ over inheritance.

Answer 33

composition

Question 34

GoF Principle:

Favor object composition over _________.

Answer 34

inheritance