
 
A GNU parser is use to parse gnu like arguments passed. It is now deprecated and is replaced by DefaultParser.
CLITester.java
import org.apache.commons.cli.CommandLine;
import org.apache.commons.cli.CommandLineParser;
import org.apache.commons.cli.GnuParser;
import org.apache.commons.cli.Options;
import org.apache.commons.cli.ParseException;
public class CLITester {
   public static void main(String[] args) throws ParseException {
      //Create GNU like options
      Options gnuOptions = new Options();
      gnuOptions.addOption("p", "print", false, "Print")
         .addOption("g", "gui", false, "GUI")
         .addOption("n", true, "Scale");
      CommandLineParser gnuParser = new GnuParser();
      CommandLine cmd = gnuParser.parse(gnuOptions, args);
      if( cmd.hasOption("p") ) {
         System.out.println("p option was used.");
      }
      
      if( cmd.hasOption("g") ) {
         System.out.println("g option was used.");
      }
      
      if( cmd.hasOption("n") ) {
         System.out.println("Value passed: " + cmd.getOptionValue("n"));
      }
   } 
}
Run the file while passing -p -g -n 10 as option and see the result.
java CLITester -p -g -n 10 p option was used. g option was used. Value passed: 10