Java翻倍并获得双倍

Question

I have seen numerous examples of rounding using DecimalFormat and NumberFormat but these return Strings when used. Yes I know that one can use parse to get the number back, however this adds complexity.

So how does one round a double to a given precision and get a double back with as few midsteps as possible?

Answer 1

There's no real way to do that. You could do the old (X*10^N)/10^N trick, I suppose, but you may not get the arbitrary precision you want. That's the trick with floating point numbers. If you want arbitrary precision, you need to use BigDecimal.