Abstract Factory Pattern. Human Computer Interaction Research University of Nevada, Reno

Transcription

1 Abstract Factory Pattern

2 Pattern Categories!Behavioral Patterns» observer» decorator» strategy!creational Patterns» factory method» abstract factory

3 Problem Too many dependencies to concrete classes makes your software difficult to maintain and modify

4 example client B1 A1 B2 A2 B3 A3 client depends on six classes

5 Dependency Inversion principle Depend upon Abstractions, do not depend upon concrete classes

6 Factory Method client client depends on one class abstraction B1 A1 B2 A2 B3 A3

7 Guidelines!No variable should have a reference to a concrete class!no class should derive from a concrete class!no method should override an implemented method of any of its base classes.

8 Example ipad iphone

9 Instead of creating this Factory A4 8GB A5 16GB Factory A4 8GB A5X 32GB

10 Look at ingredients AT&T Verizon iphone CPU A4 A4 protocol GSM CDMA memory 8 16 ipad CPU A5 A5X protocol GSM CDMA memory 16 32

11 Create Abstractions CPU protocol memory A4 A5X A5 GSM CDMA device ipad iphone

12 Create Ingredient Factory CPU protocol memory A4 A5X A5 GSM CDMA Factory ipad()

13 Abstract Factory Pattern The Abstract Factory Pattern provides an interface for creating families of related or dependent objects without specifying their concrete classes.

14 Abstract Factory each factory knows how to make the right ingredients

15 Exercise II B.I.G

16 NV Slot store public interface SlotComponentFactory { public Cabinet createcabinet(); public Display createdisplay(); // public GPU(); // public CPU(); public interface Cabinet { public String tostring(); public class largecabinet implements Cabinet { public String tostring() { return "A large cabinet";

17 NV Slot Component Factory public class NVSlotComponentFactory implements SlotComponentFactory public Cabinet createcabinet() { return new largecabinet(); public Display createdisplay() { return new LCD();

18 NJ Slot Factory public class NJSlotFactory extends SlotFactory { protected Slot makeslot(string item) { Slot slot=null; SlotComponentFactory componentfactory = new NJSlotComponentFactory(); if (item.equals("bonus")) { slot=new BonusSlot(componentFactory); slot.setname("new Jersey Style Bonus Slot"); else if (item.equals("progressive")) { slot=new ProgressiveSlot(componentFactory); slot.setname("new Jersey Style Progressive Slot"); return slot;

19 Bonus Slot public class BonusSlot extends Slot { SlotComponentFactory componentfactory; public BonusSlot(SlotComponentFactory componentfactory) { this.componentfactory= componentfactory; void build() { System.out.println("Building " + name); cabinet = componentfactory.createcabinet(); display = componentfactory.createdisplay();