Evaluating Software Design Patterns
— the "Gang of Four" patterns implemented in Java 6

@Pattern(name="Abstract Factory", scope=Object, purpose=Creational, participants={"AbstractFactory","ConcreteFactory","AbstractProduct","ConcreteProduct","Client"})

Package dk.rode.thesis.abstractfactory

Implementations and examples of the Abstract Factory design pattern [Gamma95, p.87].


Interface Summary
AbstractionFactory<E> A sequence abstraction factory can create sequence abstractions.
GeneratorFactory<E,P> A generator factory can create sequence value generators used as implementations for sequence abstractions.
SequenceFactory<E,P> A sequence factory provides a general creation method to create initialised sequences in a single step.

Class Summary
CollectionValueFactory<E extends Serializable> A collection value factory creates specific SequenceValueCollection objects based on the supplied type of collection to the creation method.
Main Abstract Factory tests.
MemorizableAbstractionFactory<E> A memorizable abstraction factory creates memorizable sequence abstractions.
PrototypicalAbstractionFactory<E> A prototypical abstraction factory creates sequence abstractions based on a prototype supplied at construction time.
PrototypicalFactory<T extends StrictCopyable<T>> A prototypical factory creates instances of a specific type of copyable type based on a prototype supplied at construction time.
PrototypicalRegistry A prototypical registry creates instances of copyable objects based on registered prototypes.
PrototypicalSequenceFactory<E> A prototypical sequence factory creates sequences based on a prototype supplied at construction time.
RangeValueFactory A range value factory creates value range generators.
StandardAbstractionFactory<E> A standard abstraction factory creates sequence abstractions.
StandardFactory<E,P> A standard factory can create sequence abstractions as well as the sequence value generators used as the implementations for the abstractions, and further more provides a convenient creation method to create sequences in a single step.
SynchronisedAbstractionFactory<E> A synchronised abstraction factory creates synchronised sequence abstractions.

Package dk.rode.thesis.abstractfactory Description

Implementations and examples of the Abstract Factory design pattern [Gamma95, p.87].


Here, the AbstractProduct participant is represented by the SequenceAbstraction, SequenceValueGenerator, and Sequence types. Hence, the ConcreteProduct participant is represented by any class inheriting or implementing the aforementioned types, including SequenceAbstraction itself.

A factory type is defined to create each of the abstract product types, respectively the AbstractionFactory, GeneratorFactory, and SequenceFactory interfaces. All theses factories represent the AbstractFactory participant.

Several different factory implementations have been made to represent the ConcreteFactory participant, each capable of creating one or more of described product types. The StandardFactory implements all three factory types, but uses composition to let AbstractionFactory and GeneratorFactory instances perform the actual creation; sequences created by it are simply initialised SequenceAbstraction instances. Specific abstraction factories include StandardAbstractionFactory and MemorizableAbstractionFactory, while CollectionValueFactory and RangeValueFactory are the only two generator factories.

Several prototypical factories are also provided, that create products based on prototypes. The PrototypicalFactory is a stand-alone prototypical factory, while the PrototypicalRegistry class is a registry that can create multiple product types.

Finally, the Client participant is represented by the Main class, which creates and uses the created sequences.

UML Class Diagram:

Implementation notes:
The PrototypicalSequenceFactory factory illustrates how the Prototype pattern can be used to create objects based on prototypes. The PrototypicalSequenceFactory can create any type of sequence based on a prototype supplied at construction time. The PrototypicalAbstractionFactory provides similar functionality, but for SequenceAbstraction instances.

The use of prototypes is a possible alternative to using reflection to create different types of products. However, the PrototypicalRegistry illustrates that using a registry to store prototypes to create can cause problems with type safety when generic types are created. The generic Factory class illustrates how reflection can be used to make a completely generic factory type to create any type of instantiable product, providing the product type has a usable constructor. Ideally, it should be used in an Abstract Factory implementation via composition, but here we simply illustrate its use directly in Main and combine products as need be.

Gunni Rode / rode.dk

Gunni Rode / rode.dk

Feel free to use and/or modify the Java 6 source code developed for this thesis AT YOUR OWN RISK, but note that the source code comes WITHOUT ANY — and I do mean WITHOUT ANY — form of warranty WHAT SO EVER!

The original thesis and source code are available at rode.dk/thesis.