Question

I want to implement or use some library for an intelligent decimal cut off.

I mean that I would like to get: from 3.456432 -> 3.4, from 0.0000023232432 -> 0.000002 and from 0.000000000001 -> 0.0 (or something like that). I need this feature for a convinient user GUI.

Thereby I need to reduce number of digits that are not equal to zero. I need to keep 1-3 most significant digits and other set to zero.

Answer 1

If it is of any help, you can use the following method to round a double to a specified number of significant digits. There are however no functionality in the standard API to output the result in a reasonable manner:

private static double round(double v, int sigDigits) {
    double f = Math.pow(10, Math.ceil(Math.log10(Math.abs(v))) - sigDigits);
    return Math.round(v/f)*f;
}