some sites on design patterns

http://www.vincehuston.org/dp/

http://www.cmcrossroads.com/bradapp/javapats.html

http://dotnet.zcu.cz/NET_2006/Papers_2006/short/B31-full.pdf
http://zone.ni.com/devzone/cda/tut/p/id/3024

http://www.javacodegeeks.com/2011/02/state-pattern-domain-driven-design.html

http://nurkiewicz.blogspot.com/2009/09/state-pattern-introducing-domain-driven.html

factory

http://chaoticjava.com/posts/factory-design-pattern-made-simple-using-enums/