Question

Possible Duplicate:
Floating point arithmetic not producing exact results in Java
Float numbers in Java

Please see Code Below.

public class TestSum {

public static void main(String[] args) {
    float a = 4.8f;//try with 4.7f
    float b = 4.5f;//try with 4.6f
    double sum = a + b;
    System.out.println(sum);
 }
}

(4.8f+4.5f) sum=9.300000190734863

But when, i tried (4.7f+4.6f) it gives sum = 9.299999237060547
Again,

(1.8f+1.5f) sum=3.299999952316284.
(1.7f+1.6f) sum=3.3000001907348633.

But,

(2.8f+2.5f) sum=5.300000190734863.
(2.7f+2.6f) sum=5.300000190734863.

I want to Understand, how this works.
Thanks in advance.

Answer 1

I want to understand how this works.

See the info. & links (listed below) on the floating point tag Wiki.

• What Every Computer Scientist Should Know About Floating-Point Arithmetic
• floating-point-gui.de

What’s best solution for this then…?

BigDecimal, or more commonly, formatting the output using DecimalFormat.