How to force Java to throw arithmetic exception?

Question

How to force Java to throw arithmetic exception on dividing by 0.0 or extracting root from negative double? Code follows:

   double a = 1; // or a = 0 to test division by 0
   double b = 2;
   double c = 100;

   double d = b*b - 4*a*c;
   double x1 = (-b - Math.sqrt(d)) / 2 / a;
   double x2 = (-b + Math.sqrt(d)) / 2 / a;

Answer 1

This code will throw an ArithmeticException:

int x = 1 / 0;

Answer 2

I think, you'll have to check manually, e.g.

public static void checkValue(double val) throws ArithmeticException {
    if (Double.isInfinite(val) || Double.isNaN(val))
        throw new ArithmeticException("illegal double value: " + val);
}

Answer 3

It's not possible to make Java throw exceptions for these operations because Java implements the IEEE 754 standard for floating point arithmetic, which mandates that these operations should return specific bit patterns with the meaning "Not a Number" or "Infinity".

If you want to treat these cases specially, you can compare the results with the corresponding constants like Double.POSITIVE_INFINITY (for NaN you have to use the isNAN() method because NaN != NaN). Note that you do not have to check after each individual operation since subsequent operations will keep the NaN or Infinity value. Just check the end result.