Variable names used when reporting options in exceptions text

[AlexFalappa]

Consider the following, purposely atypical, example:

public class App {

    public static void main(String[] args) {
        CmdLineArgs cla = new CmdLineArgs();
        CommandLine cl = new CommandLine(cla);
        try {
            cl.parse(args);
            System.out.println(cla.foo.getAbsolutePath());
            System.out.println(cla.bar.getAbsolutePath());
        } catch (CommandLine.ParameterException pe) {
            System.err.println(pe.getMessage());
            CommandLine.usage(cla, System.out);
        }

    }

}

@CommandLine.Command(name = "app")
class CmdLineArgs {

    @CommandLine.Parameters(arity = "1", paramLabel = "IN_FILE", description = "The input file")
    File foo;

    @CommandLine.Option(names = "-o", paramLabel = "OUT_FILE", description = "The output file", required = true)
    File bar;
}

When launched without arguments produces:

Missing required options [bar, foo]
Usage: app -o=OUT_FILE IN_FILE
      IN_FILE                 The input file
  -o= OUT_FILE                The output file

As you can see there are little cues for an user to link the variable names used in the exception text to the usage message.

It would be better to use the paramLabel string, if available, or, in the case of options, one of the names strings and to use the variable name as fallback.

[remkop]

Thank you for raising this!
I agree: the error message should be consistent with the usage message.
I like your suggestions for fixing this.

[remkop]

I made a number of improvements in this area.
For the example above, the error message is now:

Missing required options [-o=OUT_FILE, params[*]=IN_FILE]

Please verify.