Is Factory Method pattern without abstract methods possible?

Question

Let's say one Java program that does not have abstract methods, is it possible to implement the Factory Method pattern without abstract methods?

Answer 1

Absolutely: a factory method does not need to be an abstract one - it could be a non-abstract method with a default implementation throwing an exception, or it could be a method of an interface, which is always abstract.

interface Product {
    void doSomething();
}
interface Creator {
     Product create(String someData);
}
class ProductX implements Product {
    public void doSomething() {
         System.out.println("X");
    }
}
class ProductY implements Product {
    public void doSomething() {
         System.out.println("y");
    }
}
class XYFactory implements Creator {
    public Product create(String someData) {
        if ("X".equals(someData)) {
            return new ProductX();
        }
        if ("Y".equals(someData)) {
            return new ProductY();
        }
        return null;
    }
}