code: public void addNextValue(Object val) {
      String valCountStr = val.toString();
      int pos = valCountStr.lastIndexOf("\t");
      String valStr = valCountStr;
      String countStr = "1";
      if (pos >= 0) {
        valStr = valCountStr.substring(0, pos);
        countStr = valCountStr.substring(pos + 1);
      }
      
      Long count = (Long) this.items.get(valStr);
      long inc = Long.parseLong(countStr);
  
      if (count == null) {
        count = inc;
      } else {
        count = count.longValue() + inc;
      }
      items.put(valStr, count);
    }
docs: add the given val to the aggregator.
  
  @param val the value to be added. It is expected to be a string
  in the form of xxxx\tnum, meaning xxxx has num occurrences.