Rounding a double to 5 decimal places in Java ME

Question

How do I round a double to 5 decimal places, without using DecimalFormat?

Answer 1

You can round to the fifth decimal place by making it the first decimal place by multiplying your number. Then do normal rounding, and make it the fifth decimal place again.

Let's say the value to round is a double named x:

double factor = 1e5; // = 1 * 10^5 = 100000.
double result = Math.round(x * factor) / factor;

If you want to round to 6 decimal places, let factor be 1e6, and so on.

Answer 2

Multiply by 100000. Add 0.5. Truncate to integer. Then divide by 100000.

Code:

double original = 17.77777777;
int factor = 100000;
int scaled_and_rounded = (int)(original * factor + 0.5);
double rounded = (double)scaled_and_rounded / factor;