Question

I’ve a variable price which is defined this way:

   double price;
   price = 7.6;

Up to here everything is right. The problem is that when I make this:

   price = 7.6 * 3;

What i get is

   price = 22.799999999999999999999999997

instead of

   price = 22.80 

which is what i need.

Any ideas about how to solve this?? Thank you.

Answer 1

Use BigDecimal or store your amounts of money in cents and use long.

For reasons read Effective Java Item 48.

In summary:
Don’t use double and float when you need exact values. These datatypes cannot represent numbers wich are a negative power of ten. (e.g. 0.1)
Use BigDecimal instead. For monetary values long or int are more suitable in most cases.

Your example using long:

long price; //store values in euro cents
price = 760 * 3; //price is now 2280 cents