Patterns Questions

Front 1

Name 5 commonly used design patterns.

Back 1

Null Object, Factory, Observer, Decorator and Strategy.

Front 2

Explain the Model View Controller pattern.

Back 2

Model View Controller (MVC) pattern creates applications that separate the different aspects of the application (input logic, business logic, and UI logic), while providing a loose coupling between these elements. In this way, they can be tested separately and the loose coupling facilitates the support of several different UI's.

Front 3

Explain the Null Object pattern.

Back 3

Provide an object as a surrogate for the lack of an object of a given type. The Null Object Pattern provides intelligent do nothing behavior, hiding the details from its collaborators.

Front 4

Explain the Factory pattern.

Back 4

The factory pattern creates objects without exposing the instantiation logic to the client.
It also provides a means of referring to the newly created object through a common interface.

Front 5

Explain the Observer pattern.

Back 5

Simply put, the Observer pattern is a pub-sub arrangement. A number of Observing objects subscribe to information produced by a publishing object.

Front 6

Explain the Decorator pattern.

Back 6

This pattern provides a means for extending a class's functionality at runtime. This is done usually by wrapping the class so that the method in question can be over-ridden by a method that calls the super class method as well as some other method.

Front 7

Explain the Strategy pattern.

Back 7

Define a family of algorithms, encapsulate each one, and make them interchangeable. Strategy lets the algorithm vary independently from clients that use it.