Parse command line in Java 8 without dependencies

Args.java

public class Args {
  private static final String USAGE  //
    = String.join("\n",
                  "",
                  "tool [options] files...",
                  "",
                  "",
                  "Options:",
                  " -d PORT         : filter on given port",
                  " -h              : prints this help",
                  "");

  final List<String> args = new ArrayList<>();

  public int dstPort;

  public static class Usage extends RuntimeException {

    Usage() {
      super(USAGE);
    }

    Usage(String msg) {
      super(msg + "\n" + USAGE);
    }
  }

  Args(String[] argv) {
    try {
      for (int i = 0; i < argv.length; i++) {
        String arg = argv[i];

        if (arg.startsWith("-")) {
          switch (arg) {
          case "-h":
            throw new Usage();
          case "-d":
            dstPort = Integer.parseInt(argv[++i]);
            break;
          default:
            throw new Usage("Unknown option: " + arg);
          }
        }
        else {
          args.add(arg);
        }
      }
    }
    catch (Usage e) {
      throw e;
    }
    catch (Exception e) {
      throw new Usage(e.toString());
    }

    if (args.isEmpty())
      throw new Usage();
  }
}