Handling command-line arguments in the controller

You can add code to your controller class to handle POSIX-style command line arguments, just like the main FrontEnd class for CT does.

This is done through a library called GetOpt, for which there is a good general tutorial available.

To use the Java implementation of GetOpt in your controller, include the following imports:

import gnu.getopt.Getopt;
import gnu.getopt.LongOpt;

The following is an example of part of a main method in a controller that uses GetOpt.

It has three possible command-line options

• -h or --help
• -n or --numRounds num
• -f or --fixedReward num

      public static void main(String[] args)
      {
  
          LongOpt[] longopts = new LongOpt[3];
          longopts[0] = new LongOpt("help", LongOpt.NO_ARGUMENT, null, 'h');
          longopts[1] = new LongOpt("fixedReward", LongOpt.REQUIRED_ARGUMENT, null, 'f');
          longopts[2] = new LongOpt("numRounds", LongOpt.OPTIONAL_ARGUMENT, null,'n');
          Getopt go = new Getopt("coloredtrails", args, "f:n:", longopts);
          go.setOpterr(true);
          int c;
          String arg;
  
          boolean useFixedReward = false;
          int fixedReward = 0;
  
          try {
              while ((c = go.getopt()) != -1) {
                  switch (c) {
                      case 'h':
                          printUsage();
                          break;
                      case 'f':
                          useFixedReward = true;
                          fixedReward = Integer.parseInt(go.getOptarg());
                          break;
                      case 'n':
                          numRounds = Integer.parseInt(go.getOptarg());
                          break;
                      default:
                          System.out.println("Unknown option:" + c);
                          printUsage();
                          System.exit(1);
                          break;
                  }
              }
          } catch (Exception e) {
              printUsage();
              System.err.println("Error: Bad Input.");
              System.exit(1);
          }