So what does JSAP actually do?
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## So what does JSAP actually do?

`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 suppored by `JSAP`; you may want to skip right to the javadocs and check it out.

`JSAP` provides not only for default values for its parameters, but for a cascading chain of values. With a couple extra lines of code, `JSAP` will, for example:

1. Parse the command line.

2. For any omitted parameters, look for values in ~/.yourProgramName.conf

3. For any still omitted parameters, look for values in /etc/yourProgramName.conf

4. For any still omitted parameters, use the default values (if any) specified by the developer.

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