code: public static String min(String... values) {
          BigDecimal bd;
          BigDecimal bd2;
          try {
              int start = 0;
              while (values[start] == null) {
                  start++;
              }
              bd = new BigDecimal(values[start]);
              for (int i = start + 1; i < values.length; i++) {
                  if (values[i] == null) {
                      continue;
                  }
                  bd2 = new BigDecimal(values[i]);
                  if (bd.compareTo(bd2) > 0) {
                      bd = bd2;
                  }
              }
              return bd.toString();
          } catch (Exception e) {
              return null;
          }
      }
docs: Returns the minimum number from a group of input value.
  
  Any numeric string recognized by {@code BigDecimal} is supported.
  
  @param values One of more valid number strings
  
  @return the minimum number.
  
  @see BigDecimal