Applied Design Patterns with Java

Creational :: Factory Method (107) {C ch 4}

Applicability

Use the Factory Method pattern when

• a class can't anticipate the class of objects it must create.
• a class wants its subclasses to specify the objects it creates.
• classes delegate responsibility to one of several helper subclasses, and you want to localize the knowledge of which helper subclass is the delegate.

Structure

Participants

Product (Document) - defines the interface of objects the Factory Method creates.

ConcreteProduct (MyDocument) - implements the Product interface.

Creator (Application)

• declares the Factory Method, which returns an object of type Product. Creator may also define a default implementation of the Factory Method that returns a default ConcreteProduct object.
• may call the Factory Method to create a Product object.

ConcreteCreator (MyApplication) - overrides the Factory Method to return an instance of a ConcreteProduct.

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