Question

I have got a Problem, I am developing an Application which should be able to do some mathematic calculations. These calculations have to be exact (or rather not obviously wrong)

But this simple Code

double a = 3.048d;
double b = 1000d;

double c = a / b;

gives me a wrong result c is not 0.003048 as expected instead it is 0.0030480000000000004 which is obviously wrong.

double d = 3.048 / 1000; 

this second code-snipet gives the correct result.

I am aware that all floatingpoint arithmetic is not exact when calculating with computers but I don’t know how to solve this problem.

thanks in advance!
Ludwig

Developing for:
– Android 2.2
Testdevice:
– HTC Desire

Answer 1

What you need to use for exact percision is the BigDecimal object:

BigDecimal a = new BigDecimal("3.048");
BigDecimal b = new BigDecimal(1000);

BigDecimal c = a.divide(b);

System.out.println(c); //0.003048