  args4j comes with a built-in support for parsing options into several Java datatypes, such as <<<int>>>, <<<String>>>, and <<<Enum>>>. This support can be extended by writing {{{apidocs/org/kohsuke/args4j/spi/OptionHandler.html}OptionHandler}} implementation in an application and registering it to the <<<CmdLineParser>>> class.

  In fact most of the built-in suppor is implemented as using this mechanism. See the source code for some of the OptionHandler class for details of how to do this.