Yawen Hou
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Computer Science Quiz on Design Patterns, created by Yawen Hou on 18/03/2019.

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Erica Solum
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Yawen Hou
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Design Patterns

Question 1 of 19

1

Adapter is:

Select one of the following:

  • creational pattern which defines an interface for creating objects, but delegates the actual responsibility for selecting the class and instantiating the object to a subclass

  • structural pattern that lets you add responsibilities to an object dynamically

  • structural pattern that adapts a class with an incompatible interface to fit your needs

Explanation

Question 2 of 19

1

Observer is:

Select one of the following:

  • behavioral pattern that allows an object to notify other objects when it changes (without knowing what the other objects are)

  • behavioral pattern that lets subclasses redefine certain steps of an algorithm without changing the algorithm's structure.
    (Similar to Strategy but allows steps to be changed instead of whole implementation)

  • behavioral pattern that allows a class to use different variants of an algorithm

Explanation

Question 3 of 19

1

Factory method is:

Select one of the following:

  • creational pattern which defines an interface for creating objects, but delegates the actual responsibility for selecting the class and instantiating the object to a subclass

  • creational pattern which provides an interface for creating families of related(or dependent) objects without specifying their concrete classes

  • behavioral pattern that lets subclasses redefine certain steps of an algorithm without changing the algorithm's structure.
    (Similar to Strategy but allows steps to be changed instead of whole implementation)

Explanation

Question 4 of 19

1

Abstract Factory is:

Select one of the following:

  • creational pattern which provides an interface for creating families of related(or dependent) objects without specifying their concrete classes

  • structural pattern that lets you add responsibilities to an object dynamically

  • behavioral pattern that allows a class to use different variants of an algorithm

Explanation

Question 5 of 19

1

Decorator is:

Select one of the following:

  • structural pattern that lets you add responsibilities to an object dynamically

  • behavioral pattern which encapsulates a request as an object

  • structural pattern that adapts a class with an incompatible interface to fit your needs

Explanation

Question 6 of 19

1

Command is:

Select one of the following:

  • behavioral pattern which encapsulates a request as an object

  • behavioral pattern that allows a class to use different variants of an algorithm

  • behavioral pattern that allows an object to notify other objects when it changes (without knowing what the other objects are)

Explanation

Question 7 of 19

1

Use case for abstract factory:

Select one or more of the following:

  • system should be independent of product creation

  • want to configure with multiple families of products

  • want to ensure that a product family is used together

  • when an algorithm consists of varying and invariant parts that must be customized

  • a class can't anticipate the class of objects it must create

Explanation

Question 8 of 19

1

Use cases for factory method:

Select one or more of the following:

  • a class can't anticipate the class of objects it must create

  • a class wants its subclasses to specify the objects it create

  • you need to use several subclasses, but its impractical to adapt their interfaces by subclassing each one

  • many classes differ only in their behavior

  • want to configure with multiple families of products

Explanation

Question 9 of 19

1

Use cases for decorator:

Select one or more of the following:

  • add responsibilities to individual objects dynamically and transparently

  • when responsibilities for objects can be withdrawn

  • when extension of functionality by subclassing is impractical

  • parameterize objects by an action to perform

  • client needs different variants of an algorithm

  • system should be independent of product creation

Explanation

Question 10 of 19

1

Use cases for command:

Select one or more of the following:

  • parameterize objects by an action to perform

  • specify, queue, and execute requests at different times

  • structure a system around high-level operations built out of primitives

  • you want to create a reusable class that cooperates with unrelated classes that might not have compatible interfaces

  • client needs different variants of an algorithm

  • system should be independent of product creation

Explanation

Question 11 of 19

1

Bridge pattern:

Select one of the following:

  • Decouples an abstraction from an implementation so the two can vary independently

  • Provides a unified interface to a set of interfaces in a subsystem. Facade defines a higher-level interface making the subsystem easier to use.

  • Provide a surrogate or placeholder for another object to control access to it

Explanation

Question 12 of 19

1

Mediator is:

Select one or more of the following:

  • Defining an object that encapsulates how a set of objects interact.

  • A way for controlling communication between classes or entities.

  • Use sharing to support large numbers of fine-grained objects efficiently

  • Compose objects into tree structures to represent part-whole hierarchies

Explanation

Question 13 of 19

1

Chain of Responsibility is:

Select one of the following:

  • Avoid coupling the sender of a request to its receiver by giving more than one object a chance to handle the request

  • Encapsulate a request as an object, thereby letting you parameterize clients with different requests, queue or log requests, and support undoable operations

  • Provide a way to access the elements of an aggregate object sequentially without exposing its underlying representation

  • Define an object that encapsulates how a set of objects interact

Explanation

Question 14 of 19

1

Facade:

Select one of the following:

  • Provides a unified interface to a set of interfaces in a subsystem

  • Converts the interface of a class into another interface clients expect

  • Attaches additional responsibilities to an object dynamically

  • Provides a surrogate or placeholder for another object to control access to it

Explanation

Question 15 of 19

1

Flyweight:

Select one of the following:

  • Uses sharing to support large numbers of fine-grained objects efficiently

  • Specifies the kinds of objects to create using a prototypical instance, and create new objects by copying this prototype

  • Defines the skeleton of an algorithm in an operation, deferring some steps to subclasses

  • Represents an operation to be performed on the elements of an object structure

Explanation

Question 16 of 19

1

Proxy:

Select one of the following:

  • Provides a surrogate or placeholder for another object to control access to it

  • Has a simulated object that mimics the behavior of a real object in controlled ways1

  • Specify the kinds of objects to create using a prototypical instance, and create new objects by copying this prototype

  • Define the skeleton of an algorithm in an operation, deferring some steps to subclasses

Explanation

Question 17 of 19

1

Visitor:

Select one of the following:

  • Lets you define a new operation without changing the classes of the elements on which it operates

  • Attach additional responsibilities to an object dynamically

  • Decouple an abstraction from an implementation so the two can vary independently

  • Define a family of algorithms, encapsulate each one, and make them interchangeable

Explanation

Question 18 of 19

1

Model-View-ViewModel:

Select one of the following:

  • Decouples the model from the view, uses data binding from the view to the middle layer, and allows UI/UX designers to work almost independently from application developers

  • Define a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically

  • Represent an operation to be performed on the elements of an object structure

Explanation

Question 19 of 19

1

Data Access Object:

Select one of the following:

  • Provides an abstract interface to some type of database or other persistence mechanism.

  • Defines a family of algorithms, encapsulate each one, and make them interchangeable

  • Compose objects into tree structures to represent part-whole hierarchies

Explanation

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