Floating Point Casting in Java

Question

Casting for integers is very straightforward, the extra bits simply disappear.

But, is it important to understand what is happening under the hood for casting floating point? I've tried to read information on how floating point is calculated, but I have yet to find one that explains it well. At least that's my excuse. I get the basic idea although the calculation of the mantissa is a bit difficult.

At least up to Java 7, I understand that floating points cannot be used in bitwise operations. Which makes sense because of how they are stored internally. Is there anything important that is needed to know on how floating points operate or are cast?

So, to Summarize:

Is it important to understand the internal workings of floating point like integers?

What is the internal process of casting a floating point to an integer?

Answer 1

What is the internal process of casting a floating point to an integer?

Java calls the machine code instruction which does this in compliance with the IEEE-754 standard. There is nothing for Java to do as such. If you want to know how casting works I suggest you read the standard.

Basically, the mantissa is shifted by the exponent and the sign applied. i.e. a floating point number is sign * 2^exponent * mantissa and all it does is perform this calculation and drop and fractional parts.