使用decimalFormat错误设置精度 - Java

Question

I am attempting to use the DecimalFormat java class for the first time, and I am running into a strange issue. I would like 125.295 to round to 125.30. I would think the format should automatically include the 0, but maybe I'm incorrect.

double num = 125.295;
DecimalFormat df = new DecimalFormat("#.##");
df.setRoundingMode(RoundingMode.HALF_UP);
String str = df.format(num);
System.out.println(str); //this is yielding 125.3 instead of 125.30

Please help and thank you in advance!

Answer 1

The DecimalFormat class treats '#' as "hide trailing zeroes" or '0' as "show the zeroes". As per the API for DecimalFormat:

0   Number  Yes Digit
#   Number  Yes Digit, zero shows as absent

So you should use DecimalFormat("#.00") instead of DecimalFormat("#.##") if you want it to show trailing zeroes.

Answer 2

Try to use DecimalFormat like this:

   double num = 125.295;
   DecimalFormat df = new DecimalFormat("###.00");
   System.out.println("sum (DecimalFormat) : " + df.format(num));

Output:

   125.30