Java: Is (int) double reliable?

Question

When I perform simple math in java with doubles and other number data types, the double values seem to randomly vary a bit from the supposed result, which might be 5,59999999997 or 6,0000000002 or something. When I cast to int, the double value is obviously rounded down to the next whole number. Does this mean the double could be both 5 or 6? Or does that "5,999999999997" still count as 6 though which would be depending on the binary float value? If not, is there a way to let the negative vary be rounded up, but not lower values from 5,5 to 5,999999999996?

• I mean, I dont really want to round the value as described in my last sentence. I'd like to always round down to the next whole number, but I don't want to cause an extra decrement due to wrong double math results.

Answer 1

Converting a double to an int always rounds down. You can round to the nearest whole integer via Math.round(double). The double is varying from what you expect because of floating point error.