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Roadmap. Generics Abstract Factory Annotations Model-Driven Engineering. Design Patterns, a preview…. “Each pattern describes a problem which occurs over and over again in our environment; and it describes the core of the solution to that problem, in such a way that - PowerPoint PPT Presentation
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© O. Nierstrasz, O. Greevy, A. Kuhn
P2 — Clients and Servers
8.1
Roadmap
> Generics> Abstract Factory> Annotations> Model-Driven Engineering
© O. Nierstrasz, O. Greevy, A. Kuhn
P2 — Clients and Servers
8.2
Design Patterns, a preview…
“Each pattern describes a problem which occurs over and over again in our environment; and it describes thecore of the solution to that problem, in such a way thatyou can use this solution a million times over…”
— Christopher Alexander
QuickTime™ and a decompressor
are needed to see this picture.
© O. Nierstrasz, O. Greevy, A. Kuhn
P2 — Clients and Servers
8.3
Creational Patterns
… deal with the best way to create objects
© O. Nierstrasz, O. Greevy, A. Kuhn
P2 — Clients and Servers
8.4
Abstract Factory Pattern
> A Factory is the location in the code at which objects are created.
> Provides an interface for creating families of related dependent objects.
> Let clients create products in any family of products in an abstract way, without having to specify their concrete class.
> Separates the details of implementation of a set of objects from its general usage.
© O. Nierstrasz, O. Greevy, A. Kuhn
P2 — Clients and Servers
8.5
Structure of the Abstract Factory Pattern
AbstractFactory
createProduct()
ConcreteFactory1
createProduct()
ConcreteFactory2
createProduct()
Client
AbstractProduct
concreteProduct
© O. Nierstrasz, O. Greevy, A. Kuhn
P2 — Clients and Servers
8.6
Abstract Factory with Generics: Ludo Example
package ludo;
// NOTE interface for "Abstract Factory" pattern.
public interface Factory<T> {
public T createInstance();
}
© O. Nierstrasz, O. Greevy, A. Kuhn
P2 — Clients and Servers
8.7
The Concrete Factory
package ludo;
public class LudoFactory implements Factory<Ludo> {…
public Ludo createInstance() {initializeHome();initializeBranchings();initializeMainRing(quarterLength);initializeHomeRuns(quarterLength);initializeNests();return new Ludo(nest);
}…
We specify thetype to be Ludo
© O. Nierstrasz, O. Greevy, A. Kuhn
P2 — Clients and Servers
8.8
The Ludo Example
«interface»
AbstractFactory
createInstance() : T
LudoFactory
createInstance() : Ludo
Ludo
«interface»
Board
addPlayer(Player ) …
© O. Nierstrasz, O. Greevy, A. Kuhn
P2 — Clients and Servers
8.9
The Client drives the Ludo Game
public class Driver implements Runnable {
private Board board;public Driver(Factory<? extends Board> factory) {
this.board = factory.createInstance();board.addPlayer(new Player());board.addPlayer(new Player());board.addPlayer(new Player());
}…
public class Main {public static void main(String[] args) {
Runnable gameDriver = new Driver(new LudoFactory());gameDriver.run();
}
We specify the Game Factory we want
The Driver can drive any Board game
