public static String toAmount(long price){
List<String> str = new ArrayList<>();
BigDecimal divisor = null;
BigDecimal remainder = null;
BigDecimal dividend = new BigDecimal(price);
do {
BigDecimal[] result = dividend.divideAndRemainder(new BigDecimal(1000));
divisor = result[0];
remainder = result[1];
dividend = divisor;
str.add(remainder.toString());
} while (divisor.compareTo(new BigDecimal(1000)) > 0);
str.add(divisor.toString());
Collections.reverse(str);
String result = str.stream().reduce((sum,e)->sum += "," +e).get();
System.out.println(result);
return result;
}