The Adapter Pattern

Intent: Convert the interface of a class into another interface clients expect. Adapter lets classes work together that couldn’t otherwise because of incompatible interfaces.

Proxy Pattern

Intent : Provide a surrogate or placeholder for another object to control access to it.

The Factory Method Pattern

Intent Define an interface for creating an object, but let subclasses (concrete class that implements it) decide which class to instantiate. Factory Method lets a class defer instantiation to subclasses.

Abstract Factory

Intent : Provide an interface for creating families of related or dependent objects without specifying their concrete classes.

The Composite Pattern

Intent : Compose objects into tree structures to represent part-whole or parent-child hierarchies. Composite lets clients treat individual objects and compositions of objects uniformly.

Chain of Responsibility

Intent :Avoid coupling the sender of a request to its receiver by giving more than one object a chance to handle the request. Chain the receiving objects and pass the request along the chain until an object handles it.


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

The State Pattern

Intent :Allow an object to alter its behavior when its internal state changes. The object will appear to change its class.

The Strategy Pattern

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

The Bridge Pattern

Intent :Decouple an abstraction from its implementation so that the two can vary independently.

The Mediator Pattern

Intent : Define an object that encapsulates how a set of objects interact. Mediator promotes loose coupling by keeping objects from referring to each other explicitly, and it lets you vary their interaction independently.

The Observer Pattern

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


Intent :Represent an operation to be performed on the elements of an object structure. Visitor lets you define a new operation without changing the classes of the elements on which it operates.