Question

I have been trying to put my head around this. There are no errors but I am not seeing the desired answer:

public class Clopts {
    private static Options options = null; 

    private static final String InputDir = "i";
    private static final String OutputDir = "o";
    private String input;
    private CommandLine cmd = null; 

    static{
            options = new Options();
            options.addOption(InputDir, false, "Input Directory");
            options.addOption(OutputDir, false, "Output Directory. " + OutputDir );
        }

    public static void main(String[] args) {
        Clopts cliProg = new Clopts();
        cliProg.loadArgs(args);
    }

    private void loadArgs(String[] args){
        CommandLineParser parser = new PosixParser();
        try {
            cmd = parser.parse(options, args);
        } catch (ParseException e) {
            System.err.println("Error parsing arguments");
            e.printStackTrace();
            System.exit(1);
        }

        if (cmd.hasOption(InputDir)){
            input = cmd.getOptionValue(InputDir);
            System.out.println(input); // This is always null :(
        }
    }
}

While I am passing the argument -i foo -o bar
But I am not seeing the foo or bar every time i see is null.

Also I want to println in the main module. How do i get the options from command line and then print out what the options are.

Answer 1

When you define your options with:

options.addOption(InputDir, false, "Input Directory");
options.addOption(OutputDir, false, "Output Directory. " + OutputDir );

The false means they don’t take arguments. If you want an option value you must specify true here.