Question

Hi I’m trying to run a calculation but I can’t seem to put it all on one line, I have to split the result into two seperate lines to achieve the desired result (which seems a bit long winded).
Can anyone explain where I’m going wrong?

both x and y are doubles.

Example 1: (incorrect)

y=0.68
x= (Math.round(y* 10))/10;
result x=0

Example 2: (correct)

y=0.68
x= Math.round(y* 10);
x = x/10;
result x=0.7

thanks for your time.

Answer 1

Math.round returns variable of type long (see: Javadoc), which means that the division by 10 is performed on a long variable resulting in another long variable – that’s why you lose the precision.

To make it calculate on it as on double and return double – you have to cast the result of Math.round like this:

x= ((double)Math.round(y* 10))/10;