CODEWITHSUNDEEP
javainheritanceabstract-factory
timbmg
timbmg

Reputation: 3328

abstract factory pattern with inherit classes

I want to implement the abstract factory pattern. I have three classes

  1. A superclass (SC)
  2. A child class (childA, shall inherit from sc)
  3. A child class (childB, shall also inherit from sc)

What I've done so far is implementing the abstract factory design pattern for the superclass. I have not handeled the inheritence yet. I do not know how to implement the pattern with the two subclasses. What do I need to add?

AbstractFactory

public abstract class AbstractFactory {

    public abstract SC createNewSC();

}

SCConcreteFactory

public class SCConcreteFactory extends AbstractFactory {

    @Override
    public SC createNewSC() {
        return new SC();
    }
}

AbstractSC

public abstract class AbstractSC{
    public abstract void doStuff();
}

SC

public class SC extends AbstractSC{

    @Override
    public void doStuff() {
        System.out.println("Hello World");
    }

}

Upvotes: 1

Views: 309

Answers (2)

locoyou
locoyou

Reputation: 1697

You need to implement two factories for ChildA and ChildB respectively, for example:

public class ChildAFactory extends AbstractFactory {

    @Override
    public SC createNewSC() {
        return new ChildA();
    }
}

public class ChildBFactory extends AbstractFactory {

    @Override
    public SC createNewSC() {
        return new ChildB();
    }
}

Upvotes: 1

swinkler
swinkler

Reputation: 1701

one very detailed way to create abstract factories with inheritance is explained in this post: http://www.oodesign.com/abstract-factory-pattern.html

If your SC superclass is also abstract, you could easily take this:

public abstract class AbstractFactory {
    public abstract SC sc();
}

public class ChildAFactory extends AbstractFactory {
    public SC sc(){ return new ChildA();}
}

public class ChildBFactory extends AbstractFactory {
    public SC sc(){ return new ChildB();}
}

And like written in the above mentioned article:

class FactoryMaker{
  private static AbstractFactory pf=null;
  static AbstractFactory getFactory(String choice){
    if(choice.equals("a")){
        pf=new ChildAFactory();
    }else if(choice.equals("b")){
        pf=new ChildBFactory();
    } return pf;
  }
 }

// Client
public class Client{
  public static void main(String args[]){
    AbstractFactory pf= FactoryMaker.getFactory("a");
    SC sc = pf.sc(); // ChildA is initialized
   }
}

There are several ways to use the abstract factory - it depends on your requirements. This is a very simple approach and might change with your requirements. E.g., the solution above only tries to hide the concrete implementation. The client only knows SC.

HTH, Sabine

Upvotes: 1

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