I wanted to do some quick command-line argument parsing in Java, so I grabbed the CLI component from Jakarta Commons and gave it a whirl. Unfortunately, this component is not very good. I fit it into a jar of about 28KB, which is not large but not that small either. The resulting command-line parser is able to identify various command-line arguments, but it isn't able to do more advanced parsing such as automatically converting arguments to integers (like jargs). It also isn't able to make use of Java annotation coolness (like args4j). It has a nice feature for automatically generating help messages, but the generated option list doesn't really match what the parsers will accept. For example, the help message will say that "-gui" is a valid option, but when using the PosixParser, the parser kept misreading the "-gui" as "-g" and rejecting it for some reason. I had to switch to the BasicParser to get it to do something reasonable.
Overall, it's nothing that I can't live with, but I was hoping for something a little better from Jakarta Commons. I think they should junk the multiple parsers, and just focus on a single more full-featured one.