Structural and Behavioral Design Patterns

Purpose Defines an abstract object structure independently of the implementation object structure in order to limit coupling.

Use When

Abstractions and implementations should not be bound at compile time.

• Adapter

• Bridge

Convert the interface of a class into another interface clients expect and let classes work together, that could not otherwise because of incompatible interfaces.

• Bridge

• Adapter

• Composite

• Observer

Represents an operation to be performed on the elements of an object structure. This Pattern lets you define a new operation without changing the classes of the elements on which it operates.

• Bridge

• Mediator

• Observer

• Visitor

Permits classes with disparate interfaces to work together by creating a common object by which they may communicate and interact.

Use When

A class to be used doesn’t meet interface requirements.

• Adapter

• Bridge

Compose objects into tree structures to represent part-whole hierarchies. / Composite lets clients treat individual objects and compositions of objects uniformly.

• Bridge

• Adapter

• Composite

• Observer

Purpose Defines an abstract object structure independently of the implementation object structure in order to limit coupling.

Use When

Abstractions and implementations should be independently extensible.

• Adapter

• Bridge

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

• Strategy

• Mediator

• Observer

• Adapter

A billing application needs to interface with an HR application in order to exchange employee data, however each has its own interface and implementation for the Employee object. In addition, the SSN is stored in different formats by each system.

What pattern can we use to create a common interface between the two applications that allows them to communicate using their native objects and is able to transform the SSN format in the process?

• Adapter

• Bridge

• Chain of Responsibility

• Observer

Permits classes with disparate interfaces to work together by creating a common object by which they may communicate and interact.

Use When

Complex conditions tie object behavior to its state.

• Adapter

• Bridge

It decouples an abstraction from its implementation so that the two can vary independently.

Is it about Bridge Pattern?

• True

• False