Fastest way to get sign in Java?

Question

I\'d like to get the sign of a float value as an int value of -1 or 1.

Avoiding conditionals is always a good idea in reducing computationa

Answer 1

If you just want the IEEE 754 sign bit from the float value you can use:

/**
 * Gets the sign bit of a floating point value
 */
public static int signBit(float f) {
    return (Float.floatToIntBits(f)>>>31);
}

This is very fast and has the advantage of no branches. I think it is the fastest you can get on the JVM.

But make sure it is what you want! Especially watch out for the special cases, e.g. NaN can technically have either a 0 or 1 sign bit.