Separating double into integer and decimal parts

Question

I am trying to separate a double into the integer and decimal parts

So for example, the number 24.4 should be separated into 24 and 4.

int integer = (int)number;
double decimal = number-(int)number;
System.out.println(decimal); 

Using this method gives me the following values :

integer = 24
decimal = 0.3999999999999986

I need the value of decimal to be 4.

How can this problem be fixed ?

Answer 1

You could do a String split(...). And then Integer parseInt(...) to get back the two integer components.

Answer 2

This is because doubles aren't exactly "real numbers" - remember there are infinite number of real numbers in any range, while there are only finite number of digits in double - thus finite number of values, so some round off must occure.

The fact is, 24.4 cannot be exactly represented by double - so the fraction of your number really is something around 0.3999....
If you want an exact solution - you should use a library that gives you exact values for decimals, such as BigDecimal.

If you want to understand more about this issue of doubles being not exact - you should read more about floating points arithmetics, and this article, though high level, is also a must in order to really understand what's going on.

If you cannot understand these article just yet - just take into consideration: If you need an exact value - doubles cannot provide it - and you should use a library if this is the case.