How to detect overflow on power in Java

Question

I know that java.lang.Math provides a set of static methods to perform some operations (sum, difference, multiply, increment, decrement, negate, toInt), throwing an ArithmeticException on overflow.

Is there something similar for power?

Answer 1

No, there is nothing equivalent for pow built into Java. (The only pow methods built into Java are Math.pow, which accepts doubles and does not overflow in the same way integers do, and BigInteger.pow, which does not overflow because BigIntegers can be arbitrarily large.)

If third-party libraries are acceptable, though, Guava has e.g. IntMath.checkedPow, which does what you're looking for.

Answer 2

As Chirag said, integers throw exceptions when they overflow while doubles don't. Not to get too specific but, basically, doubles in memory are stored very similarly to scientific notation, in that they are some integer * 2^(some power), and thus never really overflow but multiply by such a large or small 2^(some power) that they completely lose their precision. So you can instead think of double overflow as when they completely lose their precision and are printed as either Infinity or -Infinity.

So, you will need to manually check that an overflow has occurred by checking if the resulting value is Double.POSITIVE_INFINITY or Double.NEGATIVE_INFINITY.

Here is some sample code to show what I mean:

public static void main(String[] args) throws Exception
{
    double a = Double.MAX_VALUE; // highest possible double
    double b = Double.MAX_VALUE; // highest possible double

    if (Math.pow(a, b) == Double.POSITIVE_INFINITY || Math.pow(a, b) == Double.NEGATIVE_INFINITY)
    {
        throw new ArithmeticException("Double Overflow");
    }
}