How can I convert integer into float in Java?

Question

I have two integers x and y. I need to calculate x/y and as outcome I would like to get float. For example as an outcome of 3/2 I would like to have 1.5. I thought that easiest (or the only) way to do it is to convert x and y into float type. Unfortunately, I cannot find an easy way to do it. Could you please help me with that?

Answer 1

You just need to cast at least one of the operands to a float:

float z = (float) x / y; 

or

float z = x / (float) y; 

or (unnecessary)

float z = (float) x / (float) y; 

Answer 2

You shouldn't use float unless you have to. In 99% of cases, double is a better choice.

int x = 1111111111; int y = 10000; float f = (float) x / y; double d = (double) x / y; System.out.println("f= "+f); System.out.println("d= "+d); 

prints

f= 111111.12 d= 111111.1111 

Following @Matt's comment.

float has very little precision (6-7 digits) and shows significant rounding error fairly easily. double has another 9 digits of accuracy. The cost of using double instead of float is notional in 99% of cases however the cost of a subtle bug due to rounding error is much higher. For this reason, many developers recommend not using floating point at all and strongly recommend BigDecimal.

However I find that double can be used in most cases provided sensible rounding is used.

In this case, int x has 32-bit precision whereas float has a 24-bit precision, even dividing by 1 could have a rounding error. double on the other hand has 53-bit of precision which is more than enough to get a reasonably accurate result.