Abstract Factory
Provide an interface for creating families of related or dependent objects without specifying their concrete classes.
Purpose: Creational
Scope: Object
Adapter
Convert the interface of a class into another interface clients expect. Adapter lets classes work together that couldn’t otherwise because of incompatible interfaces.
Purpose: Structural
Scope: Class and Object
Bridge
Decouple an abstraction from its implementation so that the two can vary independently.
Purpose: Structural
Scope: Object
Builder
Separate the construction of a complex object from its representation so that the same construction process can create different representations.
Decorator
Attach additional responsibilities to an object dynamically. Decorators provide a flexible alternative to subclassing for extending functionality.
Purpose: Structural
Scope: Object
Facade
Provide a unified interface to a set of interfaces in a subsystem. Facade defines: higher-level interface that makes the subsystem easier to use.
Purpose: Structural
Scope: Object
Factory Method
Define an interface for creating an object, but let subclasses decide which class to instantiate. Factory Method lets a class defer instantiation to subclasses.
Purpose: Creational
Scope: Class
Flyweight
Use sharing to support large numbers of fine-grained objects efficiently.
Purpose: Structural
Scope: Object
Chain of Responsibility
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.
Purpose: Behavioral
Scope: Object
Command
Encapsulate a request as an object, thereby letting you parameterize clients with different requests, queue or log requests, and support undoable operations.
Purpose: Behavioral
Scope: Object
Composite
Compose objects, into tree structures to represent part-whole hierarchies. Composite lets clients treat individual objects and compositions of objects uniformly.
Purpose: Structural
Scope: Object
Visitor
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.
Purpose: Behavioral
Scope: Object
Template Method
Define the skeleton of an algorithm in an operation, deferring some steps ‘ to subclasses. Template Method lets subclasses redefine certain steps of an algorithm without changing the algorithmʼs structure.
Purpose: Behavioral
Scope: Class
Strategy
Define a family of algorithms, encapsulate each one, and make them interchange- able. Strategy lets the algorithm vary independently from clients that use it.
Purpose: Behavioral
Scope: Object
State
Allow an object to alter its behavior when its internal state changes. The object will appear to change its class.
Purpose: Behavioral
Scope: Object
Singleton
Ensure a class only has one instance, and provide a global point of access to it.
Purpose: Creational
Scope: Object
Proxy
Provide a surrogate or placeholder for another object to control access to it.
Purpose: Structural
Scope: Object
Prototype
Specify the kinds of objects to create using a prototypical instance, and create new objects by copying this prototype.
Purpose: Creational
Scope: Object
Interpreter
Given a language, define a represention for its grammar along with an interpreter that uses the representation to interpret sentences in the language.
Purpose: Behavioral
Scope: Class
Iterator
Provide a way to access the elements of an aggregate object sequentially without exposing its underlying representation.
Purpose: Behavioral
Scope: Object
Mediator
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.
Purpose: Behavioral
Scope: Object
Memento
Without Violating encapsulation, capture and externalize an objectʼs internal state so that the object can be restored to this state later
Purpose: Behavioral
Scope: Object
Observer
Define a one-to-many dependency between objects so that when one object
changes state, all its dependents are notified and updated automatically.
Purpose: Behavioral
Scope: Object
