What is the basic difference between the Factory and Abstract Factory Design Patterns

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What is the basic difference between the Factory and Abstract Factory Patterns

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Both Factory Method and Abstract Factory keep the clients decoupled from the concrete types  Both create objects  but Factory method uses inheritance whereas Abstract Factory use composition    The Factory Method is inherited in subclasses to create the concrete objects products  whereas Abstract Factory provide interface for creating the family of related products and subclass of these interface define how to create related products    Then these subclasses when instantiated is passed into product classes where it is used as abstract type  The related products in an Abstract Factory are often implemented using Factory Method

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Source for this information taken from  http   java dzone com news intro-design-patterns-abstract  Abstract Factory vs  Factory Method The methods of an Abstract Factory are implemented as Factory Methods  Both the Abstract Factory Pattern and the Factory Method Pattern decouples the client system from the actual implementation classes through the abstract types and factories  The Factory Method creates objects through inheritance where the Abstract Factory creates objects through composition  The Abstract Factory Pattern consists of an AbstractFactory  ConcreteFactory  AbstractProduct  ConcreteProduct and Client  How to implement The Abstract Factory Pattern can be implemented using the Factory Method Pattern  Prototype Pattern or the Singleton Pattern  The ConcreteFactory object can be implemented as a  Singleton as only one instance of the ConcreteFactory object is needed  Factory Method pattern is a simplified version of Abstract Factory pattern  Factory Method pattern is responsible for creating products that belong to one family  while Abstract Factory pattern deals with multiple families of products  Factory Method uses interfaces and abstract classes to decouple the client from the generator class and the resulting products  Abstract Factory has a generator that is a container for several factory methods  along with interfaces decoupling the client from the generator and the products  When to Use the Factory Method Pattern Use the Factory Method pattern when there is a need to decouple a client from a particular product that it uses  Use the Factory Method to relieve a client of responsibility for creating and configuring instances of a product  When to Use the Abstract Factory Pattern Use the Abstract Factory pattern when clients must be decoupled from product classes  Especially useful for program configuration and modification  The Abstract Factory pattern can also enforce constraints about which classes must be used with others  It may be a lot of work to make new concrete factories  Examples  Abstract Factory Example 1 This specification for the disks to prepare different types of pasta in a pasta maker is the Abstract Factory  and each specific disk is a Factory  all Factories  pasta maker disks  inherit their properties from the abstract Factory  Each individual disk contains the information of how to create the pasta  and the pasta maker does not  Abstract Factory Example 2  The Stamping Equipment corresponds to the Abstract Factory  as it is an interface for operations that create abstract product objects  The dies correspond to the Concrete Factory  as they create a concrete product  Each part category  Hood  Door  etc   corresponds to the abstract product  Specific parts  i e   driver side door for 99 camry  corresponds to the concrete products  Factory Method Example  The  toy company corresponds to the Creator  since it may use the factory to create product objects  The division of the toy company that manufactures a specific type of toy  horse or car  corresponds to the ConcreteCreator

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Basic difference   Factory  Creates objects without exposing the instantiation logic to the client   Factory Method  Define an interface for creating an object  but let the subclasses decide which class to instantiate  The Factory method lets a class defer instantiation to subclasses  Abstract Factory  Provides an interface for creating families of related or dependent objects without specifying their concrete classes   AbstractFactory pattern uses composition to delegate responsibility of creating object to another class while Factory method pattern uses inheritance and relies on derived class or sub class to create object  From oodesign articles   Factory class diagram     Example  StaticFactory   public class ShapeFactory         use getShape method to get object of type shape     public static Shape getShape String shapeType         if shapeType    null            return null                     if shapeType equalsIgnoreCase  CIRCLE              return new Circle             else if shapeType equalsIgnoreCase  RECTANGLE              return new Rectangle             else if shapeType equalsIgnoreCase  SQUARE              return new Square                   return null           Non-Static Factory implementing FactoryMethod example is available in this post    Design Patterns  Factory vs Factory method vs Abstract Factory  When to use  Client just need a class and does not care about which concrete implementation it is getting   Factory Method class digaram     When to use  Client doesn t know what concrete classes it will be required to create at runtime  but just wants to get a class that will do the job   Abstract Factory class diagram from dzone    When to use  When your system has to create multiple families of products or you want to provide a library of products without exposing the implementation details   Source code examples in above articles are very good to understand the concepts clearly   Related SE question with code example   Factory Pattern  When to use factory methods   Differences    Abstract Factory classes are often implemented with Factory Methods  but they can also be implemented using Prototype Designs start out using Factory Method  less complicated  more customizable  subclasses proliferate  and evolve toward other creational patterns  more flexible  more complex  where more flexibility is needed  Factory Methods are usually called within Template Methods    Other useful articles   factory method from sourcemaking  abstract factory from sourcemaking  abstract-factory-design-pattern from journaldev

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The major difference in those factories is when what you want to do with the factories and when you want to use it   Sometimes  when you are doing IOC  inversion of control e g  constructor injection   you know that you can create solid objects  As mentioned in the example above of fruits  if you are ready to create objects of fruits  you can use simple factory pattern   But many times  you do not want to create solid objects  they will come later in the program flow  But the configuration tells you the what kind of factory you want to use at start  instead of creating objects  you can pass on factories which are derived from a common factory class to the constructor in IOC   So  I think its also about the object lifetime and creation

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Extending John Feminella answer   Apple  Banana  Cherry implements FruitFactory and that has a method called Create which is solely responsible of creating Apple or Banana or Cherry  You re done  with your Factory method   Now  you want to Create a special salad out of your fruits and there comes your Abstract Factory  Abstract Factory knows how to create your special Salad out of the Apple  Banana and Cherry   public class Apple implements Fruit  FruitFactory       public Fruit Create                Apple creation logic goes here          public class Banana implements Fruit  FruitFactory       public Fruit Create                Banana creation logic goes here          public class Cherry implements Fruit  FruitFactory       public Fruit Create                Cherry creation logic goes here          public class SpecialSalad implements Salad  SaladFactory       public static Salad Create FruitFactory   fruits               loop through the factory and create the fruits             then you re ready to cut and slice your fruits             to create your special salad

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Abstract factory is an interface for creating related objects but factory method is a method  Abstract factory is implemented by factory method

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By Definition we can drag out the differences of two   Factory  An interface is used for creating an object  but subclass decides which class to instantiate  The creation of object is done when it is required   Abstract Factory  Abstract Factory pattern acts as a super-factory which creates other factories  In Abstract Factory pattern an interface is responsible for creating a set of related objects  or dependent objects without specifying their concrete classes   So  in the definitions above we can emphasize on a particular difference  that is  Factory pattern is responsible for creating objects and Abstract Factory is responsible for creating a set of related objects  obviously both through an interface   Factory pattern   public interface IFactory    void VehicleType string n        public class Scooter   IFactory    public void VehicleType string n      Console WriteLine  Vehicle type      n            public class Bike   IFactory    public void VehicleType string n      Console WriteLine  Vehicle type      n            public interface IVehicleFactory    IFactory GetVehicleType string Vehicle        public class ConcreteVehicleFactory   IVehicleFactory   public IFactory GetVehicleType string Vehicle      switch  Vehicle       case  Scooter        return new Scooter        case  Bike        return new Bike        default      return new Scooter             class Program    static void Main string   args      IVehicleFactory factory   new ConcreteVehicleFactory       IFactory scooter   factory GetVehicleType  Scooter       scooter VehicleType  Scooter        IFactory bike   factory GetVehicleType  Bike       bike VehicleType  Bike        Console ReadKey           Abstract Factory Pattern   interface IVehicleFactory   IBike GetBike     IScooter GetScooter       class HondaFactory   IVehicleFactory       public IBike GetBike                return new FZS                public IScooter GetScooter                return new FZscooter              class HeroFactory  IVehicleFactory        public IBike GetBike                return new Pulsur                 public IScooter GetScooter                return new PulsurScooter              interface IBike               string Name          interface IScooter               string Name           class FZS IBike     public string Name         return  FZS          class Pulsur IBike     public string Name         return  Pulsur           class FZscooter IScooter     public string Name         return  FZscooter           class PulsurScooter IScooter    public string Name         return  PulsurScooter           enum MANUFACTURERS       HONDA      HERO    class VehicleTypeCheck          IBike bike          IScooter scooter          IVehicleFactory factory          MANUFACTURERS manu           public VehicleTypeCheck MANUFACTURERS m               manu   m                     public void CheckProducts                         switch  manu                   case MANUFACTURERS HONDA                      factory   new HondaFactory                        break                  case MANUFACTURERS HERO                      factory   new HeroFactory                        break                       Console WriteLine  Bike      factory GetBike   Name       nScooter           factory GetScooter   Name                    class Program               static void Main string   args                        VehicleTypeCheck chk   new VehicleTypeCheck MANUFACTURERS HONDA               chk CheckProducts                 chk  new VehicleTypeCheck MANUFACTURERS HERO               chk CheckProducts                 Console Read

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Example Scenario for Abstract Factory I live in a place where it rains in the rainy season  snows in winter and hot and sunny in summers  I need different kind of clothes to protect myself from the elements  To do so I go to the store near my house and ask for clothing items to protect myself  The store keeper gives me the appropriate item as per the environment and depth of my pocket  The items he gives me are of same level of quality and price range  Since he is aware of my standards its easy for him to do so  But when a rich guy from across the street comes up with the same requirements he gets an expensive  branded item  One noticeable thing is all the items he gives to me complement each other in term quality  standard and cost  One can say they go with each other  Same is the case with the items this rich guy gets  So by looking at above scenario  I now appreciate the efficiency of the shop keeper  I can replace this shopkeeper with an Abstract Shop  The items we get with abstract items and me and the rich as perspective clients  All we need is the product item which suits our needs  Now I can easily see myself considering an online store which provides a set of services to its numerous clients  Each client belongs to one of the three groups  When a premium group user opens up the site he gets great UI  highly customised advertisement pane   more options in the menus etc  These same set of features are presented to gold user but the functionality in the menu is less  advertisements are mostly relevent  and slightly less egronomic UI  Last is my kind of user  a    free group    user  I am just served enough so that I do not get offended  The UI is a bare minimum  advertisements are way off track so much so that I do not know what comes in it  lastly the menu has only log out  If I get a chance to build something like this website I would definitely consider Abstract Factory Pattern  Abstract Products   Advertisement Pane  Menu  UI painter  Abstract Factory   Web Store User Experience Concreate Factory  Premium User Experience  Gold User Experience  General User Experience

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Abstract Factory is template for creating different type of interfaces  Suppose you have project that requires you to parse different types of csv files containing quantity  price and item specific information like some contain data about fruits other about chocolates and then after parsing you need to update this information in their corresponding database so now you can have one abstract factory returning you parser and modifier factory and then this parser factory can return you Chocolate parser object Fruit Parser Object etc  and similarly Modifier Factory can return Chocolate modifier object   Fruit Modifier object etc

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Factory method  You have a factory that creates objects that derive from a particular base class  Abstract factory  You have a factory that creates other factories  and these factories in turn create objects derived from base classes  You do this because you often don t just want to create a single object  as with Factory method  - rather  you want to create a collection of related objects

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The Abstract Factory Pattern  Provide an interface for creating families of related or dependent objects without specifying their concrete classes   The Abstract Factory pattern is very similar to the Factory Method pattern  One difference between the two is that with the Abstract Factory pattern  a class delegates the responsibility of object instantiation to another object via composition whereas the Factory Method pattern uses inheritance and relies on a subclass to handle the desired object instantiation   Actually  the delegated object frequently uses factory methods to perform the instantiation    Factory pattern  Factory patterns are examples of creational patterns  Creational patterns abstract the object instantiation process  They hide how objects are created and help make the overall system independent of how its objects are created and composed   Class creational patterns focus on the use of inheritance to decide the object to be instantiated Factory Method  Object creational patterns focus on the delegation of the instantiation to another object Abstract Factory   Reference  Factory vs Abstract Factory

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I have some points to contribute with John s answer as follows   Abstract factory is a factory of factories   With the  Factory Method   because just  Factory  is ambiguous   you produce implementations  Lemon  Orange  etc   of a particular interface -- say  IFruit  This Factory could be called CitricFruitFactory   But now you want to create another kinds of fruit that the CitricFruitFactory is not able to create  Maybe the code of CitricFruitFactory wouldn t make sense if you create an Strawberry in it  strawberry is not a citric fruit     So you could create a new Factory called RedFruitFactory that produces Strawberry  Raspberry  etc   Like John Feminella said   With the Abstract Factory pattern  you produce implementations of a particular Factory interface -- e g   IFruitFactory  Each of those knows how to create different kinds of fruit    That implementatios of IFruitFactory are CitricFruitFactory and RedFruitFactory

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Abstract factory - Provides interface to create factory of related products interface PizzaIngredientsFactory         public Dough createDough      Will return you family of Dough    public Clam createClam        Will return you family of Clam    public Sauce createSauce      Will return you family of Sauce    class NYPizzaIngredientsFactory implements PizzaIngredientsFactory       Override    public Dough createDough            create the concrete dough instance that NY uses       return doughInstance             override other methods      The text book definitions are already provided by other answers  I thought I would provide an example of it too   So here the PizzaIngredientsFactory is an abstract factory as it provides methods to create family of related products   Note that each method in the Abstract factory is an Factory method in itself  Like createDough   is in itself a factory method whose concrete implementations will be provided by subclasses like NYPizzaIngredientsFactory  So using this each different location can create instances of concrete ingredients that belong to their location   Factory Method     Provides instance of concrete implementation   In the example   - createDough   - provides concrete implementation for dough  So this is a factory method  Abstract Factory     Provides interface to create family of related objects   In the example   - PizzaIngredientsFactory is an abstract factory as it allows to create a related set of objects like Dough  Clams  Sauce  For creating each family of objects it provides a factory method   Example from Head First design patterns

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My sources are   StackOverflow   tutorialspoint com  programmers stackexchange com and CodeProject com     Factory Method  also called Factory  is for decouple client of a Interface implementation  For sample we have a Shape interface with two Circle and Square implementations  We have define a factory class with a factory method with a determiner parameter such as Type and new related implementation of Shape interface     Abstract Factory contains several factory method or a factory interface by several factory implementations  For next above sample we have a Color interface with two Red and Yellow implementations  We have define a ShapeColorFactory interface with two RedCircleFactory and YellowSquareFactory  Following  code for explain this concept   interface ShapeColorFactory       public Shape getShape        public Color getColor       class RedCircleFactory implements ShapeColorFactory        Override     public Shape getShape             return new Circle                Override     public Color getColor             return new Red            class YellowSquareFactory implements ShapeColorFactory        Override     public Shape getShape             return new Square                Override     public Color getColor             return new Yellow               Here difference between FactoryMethod and AbstractFactory  Factory Method as simply return a concrete class of a interface but Abstract Factory return factory of factory  In other words Abstract Factory return different combine of a series of interface     I hope my explanation useful

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Many people will feel surprised maybe  but this question is incorrect  If you hear this question during an interview  you need to help the interviewer understand where the confusion is   Let s start from the fact that there is no concrete pattern that is called just  Factory   There is pattern that is called  Abstract Factory   and there is pattern that is called  Factory Method    So  what does  Factory  mean then  one of the following  all can be considered correct  depending on the scope of the reference     Some people use it as an alias  shortcut  for  Abstract Factory   Some people use it as an alias  shortcut  for  Factory Method   Some people use it as a more general name for all factory creational patterns  E g  both  Abstract Factory  and  Factory Method  are Factories    And  unfortunately  many people use  Factory  to denote another kind of factory  that creates factory or factories  or their interfaces   Based on their theory      Product implements IProduct  which is created by Factory  which   implements IFactory  which is created by AbstractFactory    To understand how silly this is  let s continue our equation      AbstractFactory implements IAbstractFactory  which is created by      AbstractAbstractFactory      I hope you see the point  Don t get confused  and please don t invent things that don t exist for reason   -  P S   Factory for Products is AbstractFactory  and Factory for Abstract Factories would be just another example of AbstractFactory as well

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Check here  http   www allapplabs com java design patterns abstract factory pattern htm it seems that Factory method uses a particular class not abstract  as a base class while Abstract factory uses an abstract class for this  Also if using an interface instead of abstract class the result will be a different implementation of Abstract Factory pattern    D

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I think we can understand the difference between these two by seeing a Java8 example code     interface Something      interface OneWhoCanProvideSomething        Something getSomething           interface OneWhoCanProvideCreatorsOfSomething       OneWhoCanProvideSomething getCreator          public class AbstractFactoryExample        public static void main String   args              I need something           Let s create one         Something something   new Something                  Or ask someone  FACTORY pattern          OneWhoCanProvideSomething oneWhoCanProvideSomethingOfTypeA      - gt  null          OneWhoCanProvideSomething oneWhoCanProvideSomethingOfTypeB      - gt  null             Or ask someone who knows soemone who can create something  ABSTRACT FACTORY pattern          OneWhoCanProvideCreatorsOfSomething oneWhoCanProvideCreatorsOfSomething      - gt  null             Same thing  but you don t need to write you own interfaces         Supplier lt Something gt  supplierOfSomething      - gt  null          Supplier lt Supplier lt Something gt  gt  supplierOfSupplier      - gt  null             Now the question is which way of creation should you use and why  The first way  no pattern  just plain constructor   creating by yourself is not a good idea  you have to do all the work  and your client code is tied to the particular implementation   The second way  using Factory pattern   provides you the benefit that you can pass any type of implementation  which can provide different type of something based on some condition  maybe a parameter passed to creational method    The third way  using Abstract Factory pattern   This gives you more flexibility  You can find different types of creators of something based on some condition  maybe a parameter passed    Note that you can always get away with Factory pattern by combining two conditions together  which slightly increases code complexity  and coupling   I guess that s why we rarely see real life use cases of Abstract Factory pattern

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With the Factory pattern  you produce instances of implementations  Apple  Banana  Cherry  etc   of a particular interface -- say  IFruit   With the Abstract Factory pattern  you provide a way for anyone to provide their own factory  This allows your warehouse to be either an IFruitFactory or an IJuiceFactory  without requiring your warehouse to know anything about fruits or juices

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Factory pattern  The factory produces IProduct-implementations  Abstract Factory Pattern  A factory-factory produces IFactories  which in turn produces IProducts      Update according to the comments  What I wrote earlier is not correct according to Wikipedia at least  An abstract factory is simply a factory interface  With it  you can switch your factories at runtime  to allow different factories in different contexts  Examples could be different factories for different OS es  SQL providers  middleware-drivers etc

[design-patterns] What is the basic difference between the Factory and Abstract Factory Design Patterns?

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