code: public String getResponse(String[] argv) throws IOException {
      String result = "";
      if (argv.length < 1) {
        return result;
      }
      if (argv[0].equals("-all")) {
        result += rpcCollector.getClusterUtilization();
        result += JobUtilization.legendString +
                JobUtilization.unitString;
        for (JobUtilization job : rpcCollector.getAllRunningJobUtilization()) {
          result += job;
        }
        result += TaskTrackerUtilization.legendString +
                TaskTrackerUtilization.unitString;
        for (TaskTrackerUtilization tt :
             rpcCollector.getAllTaskTrackerUtilization()) {
          result += tt;
        }
        return result;
      }
      if (argv[0].equals("-cluster")) {
        result += rpcCollector.getClusterUtilization();
        return result;
      }
      if (argv[0].equals("-job")) {
        result += JobUtilization.legendString +
                JobUtilization.unitString;
        if (argv.length == 1) {
          for (JobUtilization job : rpcCollector.getAllRunningJobUtilization()) {
            result += job;
          }
          return result;
        }
        for (int i = 1; i < argv.length; i++) {
          result += rpcCollector.getJobUtilization(argv[i]);
        }
        return result;
      }
      if (argv[0].equals("-tasktracker")) {
        result += TaskTrackerUtilization.legendString +
                TaskTrackerUtilization.unitString;
        if (argv.length == 1) {
          for (TaskTrackerUtilization tt :
               rpcCollector.getAllTaskTrackerUtilization()) {
            result += tt;
          }
          return result;
        }
        for (int i = 1; i < argv.length; i++) {
          result += rpcCollector.getTaskTrackerUtilization(argv[i]);
        }
        return result;
      }
      return result;
    }
docs: Obtain the result to print in command line
  @param argv
  @return the response to show users
  @throws IOException