JOpt Simple is my Java library for parsing command-line options. Version 3.1 adds the ability to convert arguments of options to Java types via converter objects. These are useful for types that do not meet the requirements of ArgumentAcceptingOptionSpec#ofType(), or for which you might want to do things like regex matching before passing the values along unchanged. Check out the new classes in package joptsimple.util for some examples. Have a look-see and let me know what you think.