Ways to implement factory pattern

Question

Hi I have following implmentation to factory
Method 1:
interface Product(){
public void method();
interface Factory(){
public Product createProduct();
class ConcreteProduct1 implements Product{
public void method(){
System.out.println("Concrete Product 1");
class ConcreteFactory1 implements Factory{
public Product createProduct(){
return new ConcreteProdct1();
}similarly ConcreteFactory 2 & 3
in mainclass we create as
Factory f = new ConcreteFactory1(); Product p = f.createProduct();Method 2:
Product creation as above and factory comes below as
public class Factory{
public Product createProduct(int type){
if(type == 1)
return new ConcreteProduct1();
else
return new ConcreteProdct2();
return null;
}main class comes as
Factory f = new Factory();
Product p = f.createProduct(1); which implementation is better and how?
Thanks,..

Answer 1

You should absolutely use method 1 because it is more object oriented and you don't have to keep track of a type key (if you DO should it then be implemented as an enum and not as an, ughh, int!). Actually, you may also extend the first solution with more products and concrete factories without access to the source as you just need to implement the interfaces. You don't need to edit the factory class that use type keys to track which product type to instantiate.
Well, this is at least my opinion and it is built on what I have learnt so far from reading the two good books Effective Java Programming Language Guide of Joshua Bloch and Refactoring of Martin Fowler. If you want to learn more about good use of Java and good object oriented design in practise are these books you should read.