I have a simple MVC project. My current packages:gui controller db domainI want to put extra classes which I will use, e.g. md5 hashing, email validator (methods which I will use in more than one class). Where do I put them? I will probably not use them in only one package, but in two or three (not in model for sure). Do I create an extra package, or do I put them in domain as they're static (unchangable)?
Java MVC extra classes
java;mvc
What you are looking for is a utility package.  This may include classes with static utility methods used all over the application.  Common utility classes are String operations, Date/Time, etc.Your validators could be a subclass of the utility package, but personally I would put them in the domain in a higher common directory.Refer to this answer for more details: How should I organize my source tree?