JSAP: the Java-based Simple Argument Parser

JSAP parses your command line and instantiates objects of types you specify
based upon that command line. If you configure JSAP to expect an Integer on the
command line, and the user does not provide a String that can be converted to
an Integer, JSAP will alert your program to the fact that there was a problem
with the command line. If JSAP indicates that your command line was
successfully parsed, you are guaranteed an Integer when you request that
parameter's value from your program. There's a pretty big (and growing) list of
return types supported by JSAP.

WWW: http://www.martiansoftware.com/jsap/index.html