Question

What is the standard way of storing a command line argument so that it can be accessed when required?

I can see 2 scenarios:

1. The argument is consumed immediately (A logging level)
2. The argument is not needed immediately (On failure send email to address X)

With scenario 1 It would seem quite natural to configure it upfront, however when it is a scenario more in the vein of scenario 2 I would prefer to configure that component as and when necessary (IE not up front)

So to phrase the question slightly differently how do I make my configuration options available to my entire application?

Answer 1

You can use something like that (you can store the CommandLine somewhere or use the opions right away):

Options options = createOptions();
CommandLineParser parser = new GnuParser();
CommandLine cmdLine;
int timeoutHumanMove;
try
{
    cmdLine = parser.parse(options, args, true);
    timeoutHumanMove = getTimeoutOption(cmdLine, "thm", 300);
}
catch(ParseException e)
{
    return;
}

private static int getTimeoutOption(CommandLine cmdLine, String opt, int defaultSeconds)
    throws ParseException
{
    if(cmdLine.hasOption(opt))
    {
        Number val = (Number)cmdLine.getParsedOptionValue(opt);
        return (int)(val.doubleValue() * 1000D);
    } else
    {
        return 1000 * defaultSeconds;
    }
}

private static Options createOptions()
{
    Options options = new Options();
    options.addOption(OptionBuilder.withDescription("print this help and exit").create(OptionBuilder.withLongOpt("help"), 104));

    // ...
    return options;
}