How to Java String.format with a variable precision?

Question

I\'d like to vary the precision of a double representation in a string I\'m formatting based on user input. Right now I\'m trying something like:

String foo          


        

Answer 1

You can use the DecimalFormat class.

double d1 = 3.14159;
double d2 = 1.235;

DecimalFormat df = new DecimalFormat("#.##");

double roundedD1 = df.format(d); // 3.14
double roundedD2 = df.format(d); // 1.24

If you want to set the precision at run time call:

df.setMaximumFractionDigits(precision)