Hashmap의 value값으로 key값 찾기

  public static Object getKeyFromValue(Map hm, Object value) {
    for (Object o : hm.keySet()) {
      if (hm.get(o).equals(value)) {
        return o;
      }
    }
    return null;
  }

출처 : http://www.java2s.com/Code/Java/Collections-Data-Structure/GetakeyfromvaluewithanHashMap.htm