Question

I am writing a Java application that takes command line arguments which are processed using Apache Commons CLI with the GnuParser. For reasons that are not interesting to get into, I would like it to silently ignore unknown command line options instead of throwing a ParseException but I don’t see a way to do that. I see that there is a stopAtNonOption boolean option on GnuParser.parse() but what I want is more like ignoreAtNonOption where it will keep processing options after encountering an unknown token.

I could implement my own parser to accomplish this but I’m surprised there isn’t this functionality built in so I thought I’d check before going down that road.

Example code for what I’m talking about:

try {
  CommandLine commandLine = parser.parse(options, args);
  // stopAtNonOption set to true (below) is also not what I want
  // CommandLine commandLine = parser.parse(options, args, true);
} catch (ParseException e) {
  LOG.error("error parsing arguments", e);
  throw new RuntimeException(e);
}

Answer 1

This works for me (other parsers can be derived, too):

public class ExtendedGnuParser extends GnuParser {

    private boolean ignoreUnrecognizedOption;

    public ExtendedGnuParser(final boolean ignoreUnrecognizedOption) {
        this.ignoreUnrecognizedOption = ignoreUnrecognizedOption;
    }

    @Override
    protected void processOption(final String arg, final ListIterator iter) throws     ParseException {
        boolean hasOption = getOptions().hasOption(arg);

        if (hasOption || !ignoreUnrecognizedOption) {
            super.processOption(arg, iter);
        }
    }

}