GoF Patterns

Question 1

What is the Abstract Factory pattern?

Answer 1

Abstract Factory. Allows the creation of objects without specifying their concrete type.

Question 2

What is the Builder pattern?

Answer 2

Builder. Uses to create complex objects.

Question 3

What is the Factory Method Pattern?

Answer 3

Factory Method. Creates objects without specifying the exact class to create.

Question 4

What is the Prototype Pattern?

Answer 4

Prototype. Creates a new object from an existing object.

Question 5

What is the Singleton Pattern?

Answer 5

Singleton. Ensures only one instance of an object is created.

Question 6

What is the Adapter Pattern?

Answer 6

Adapter. Allows for two incompatible classes to work together by wrapping an interface around one of the existing classes.

Question 7

What is the Bridge Pattern?

Answer 7

Bridge. Decouples an abstraction so two classes can vary independently.

Question 8

What is the Composite Pattern?

Answer 8

Composite. Takes a group of objects into a single object.

Question 9

What is the Decorator Pattern?

Answer 9

Decorator. Allows for an object’s behavior to be extended dynamically at run time.

Question 10

Wha the Facade Pattern?

Answer 10

Facade. Provides a simple interface to a more complex underlying object.

Question 11

What is the Flyweight Pattern?

Answer 11

Flyweight. Reduces the cost of complex object models.

Question 12

What is the Proxy Pattern?

Answer 12

Proxy. Provides a placeholder interface to an underlying object to
1. control access,
2. reduce cost, or
3. reduce complexity.

Question 13

What is the Chain of Responsibility Pattern?

Answer 13

Chain of Responsibility. Delegates commands to a chain of processing objects.

Question 14

What is the Command Pattern?

Answer 14

Command. Creates objects which encapsulate actions and parameters.

Question 15

What is the Interpreter Pattern?

Answer 15

Interpreter. Implements a specialized language.

Question 16

What is the Iterator Pattern?

Answer 16

Iterator. Accesses the elements of an object sequentially without exposing its underlying representation.

Question 17

What is the Mediator Pattern?

Answer 17

Mediator. Allows loose coupling between classes by being the only class that has detailed knowledge of their methods.

Question 18

What is the Memento Pattern?

Answer 18

Memento. Provides the ability to restore an object to its previous state.

Question 19

What is the Observer Pattern?

Answer 19

Observer. Is a publish/subscribe pattern which allows a number of observer objects to see an event.

Question 20

What is the State Pattern?

Answer 20

State. Allows an object to alter its behavior when its internal state changes.

Question 21

What is the Strategy Pattern?

Answer 21

Strategy. Allows one of a family of algorithms to be selected on-the-fly at run-time.

Question 22

What is the Template Method Pattern?

Answer 22

Template Method. Defines the skeleton of an algorithm as an abstract class, allowing its sub-classes to provide concrete behavior.

Question 23

What is the Visitor Pattern?

Answer 23

Visitor. Separates an algorithm from an object structure by moving the hierarchy of methods into one object.