Formatting a number with correct decimal scale

Question

I need to format a number with scale of 2 decimal places. The original number may be a whole number or a number with three decimal places. However the result should be formatted to have commas and also two decimal places always regardless of whether the original number is whole number or having decimal places.

1. When original num = 56565656.342 ==> I need 56,565,656.34
2. When original num = 56565656 ==> I need 56,565,656.00
3. When original num = 56565656.7 ==> I need 56,565,656.70

I am using the following code which is formatting the code but its failing to add the two decimal places in the above 2 & 3 cases.

String originalNumber = "56565656.7";
BigDecimal b = new BigDecimal(originalNumber).setScale(2, BigDecimal.ROUND_HALF_UP);
String formattedNumber = NumberFormat.getInstance().format(b);

Please let me know if there is any way to accomplish this in efficeint way.

Thanks in advance.

Answer 1

Take a look at the DecimalFormat class.

Alternatively you can setScale method from the BigDecimal Class.

BigDecimal bg1 = new BigDecimal("56565656.342");
BigDecimal bg2 = new BigDecimal("56565656.00");
BigDecimal bg3 = new BigDecimal("56565656.70");

DecimalFormat df = new DecimalFormat("###,###.00");
System.out.println(df.format(bg1.doubleValue()));
System.out.println(df.format(bg2.doubleValue()));
System.out.println(df.format(bg3.doubleValue()));

System.out.println(bg1.setScale(2, BigDecimal.ROUND_HALF_UP));
System.out.println(bg2.setScale(2, BigDecimal.ROUND_HALF_UP));
System.out.println(bg3.setScale(2, BigDecimal.ROUND_HALF_UP));

Yields:

56,565,656.34
56,565,656.00
56,565,656.70
56565656.34
56565656.00
56565656.70

EDIT: Also forgot to mention: If you are after precision, I would recommend you use the setScale method, using the .doubleValue() method will yield a double which can cause loss of precision.