code: String[] polled_device() {
          Util.out4.println("In polled_device command");
  
          final int nb_class = class_list.size();
          final Vector dev_name = new Vector();
          for (int i = 0; i < nb_class; i++) {
              final DeviceClass dc = (DeviceClass) class_list.elementAt(i);
              final int nb_dev = dc.get_device_list().size();
              for (int j = 0; j < nb_dev; j++) {
                  // Get DS name if it is polled
                  final DeviceImpl dev = dc.get_device_at(j);
                  if (dev.is_polled() == true) {
                      dev_name.add(dev.get_name());
                  }
              }
          }
  
          // Return an empty sequence if no devices are polled
          if (dev_name.size() == 0) {
              Util.out4.println("Return an empty sequence because no devices are polled");
              return new String[0];
          }
          // Returned device name list to caller (sorted)
          final MyComp comp = new MyComp();
          Collections.sort(dev_name, comp);
  
          final int nb_dev = dev_name.size();
          final String[] ret = new String[nb_dev];
          for (int i = 0; i < nb_dev; i++) {
              ret[i] = (String) dev_name.elementAt(i);
          }
  
          return ret;
      }
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