デザインパターン「Factory Method」 ref: http://qiita.com/shoheiyokoyama/items/d752834a6a2e208b90ca

Account.java

public class Account extends Product {

    private String owner;

    Account(String owner) {
        System.out.println("Create account: " + owner);
        this.owner = owner;
    }

    public void use() {
        System.out.println("Use account: " + owner);
    }
    public String getOwner() {
        return owner;
    }
}

AccountFactory.java

public class AccountFactory extends Factory {

    private List owners = new ArrayList();

    protected Product createProduct(String owner) {
        return new Account(owner);
    }

    protected void registerProduct(Product product) {
        owners.add( ((Account)product).getOwner() );
    }

    public List getOwners() {
        return owners;
    }
}

Factory.java

class Factory {
    AbstractDataReader create(int formatId) {
        AbstractDataReader reader = null;
        if (CSV == formatId) {
            reader = new CSVDataReaderd();
        } elseif (XML == formatId) {
            reader = new XMLDataReaderd();
        }
        return reader;
    }
}

file5.java

Create account: Ralph Johnson
Create account: Richard Helm
Create account: John Vlissides
Create account: Erich Gamma
Use account: Ralph Johnson
Use account: Richard Helm
Use account: John Vlissides
Use account: Erich Gamma

file6.java

        AbstractDataReader reader = null;
        if (CSV == formatId) {
            reader = new CSVDataReaderd();
        } elseif (XML == formatId) {
            reader = new XMLDataReaderd();
        }
        data = reader.read();

file8.java

        AbstractDataReader reader = null;
        Factory factory = new Factory;
        reader = factory(formatId);
        data = reader.read();

Main.java

public static void main(String[] args) {
        Factory factory  = new AccountFactory();
        Product account1 = factory.create("Ralph Johnson");
        Product account2 = factory.create("Richard Helm");
        Product account3 = factory.create("John Vlissides");
        Product account4 = factory.create("Erich Gamma");

        account1.use();
        account2.use();
        account3.use();
        account4.use();     
}

Product.java

public abstract class Product {

    public abstract void use();
}