private static boolean additionOverflowed(long original, long other, long result) {
        return (~(original ^ other) & (original ^ result) & SIGN_BIT) != 0;
    }
    
    private static boolean subtractionOverflowed(long original, long other, long result) {
        return (~(original ^ ~other) & (original ^ result) & SIGN_BIT) != 0;
    }

One thought on “java check/detect integer/int/long overflow/underflow”

1. I’m reasonably certain that the test in subtractionOverflowed can be simplified from:
   return (~(original ^ ~other) & (original ^ result) & SIGN_BIT) != 0;
   to:
   return ((original ^ other) & (original ^ result) & SIGN_BIT) != 0;

   Proof (I hope):
   g h (g^h) ~ ( g ^ ~ h)
   0 0 0 0 0 1 1 0
   0 1 1 1 0 0 0 1
   1 0 1 1 1 0 1 0
   1 1 0 0 1 1 0 1