JSAP not only syntactically validates your program’s command line arguments, but it converts those arguments into objects you specify. If you tell JSAP that one of your parameters is an Integer, for example, and the user does not provide a String that can be converted to an Integer when invoking the program, JSAP will throw a ParseException when you have it parse the command line. If no exception is thrown, 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 suppored by JSAP, including Integers, Floats, Dates, URLs, and even java.awt.Colors; you can also add your own in a matter of minutes.