[java] pow (x,y) in Java

What's the difference between:

Math.pow ( x,y ); // x^y

To:

x^y; // x^y

?

Will I prefer to use x^y with double type numbers? Or shell I have to use always with Math.pow() method?

In Java x ^ y is an XOR operation.

x^y is not "x to the power of y". It's "x XOR y".

Additionally for what was said, if you want integer powers of two, then 1 << x (or 1L << x) is a faster way to calculate 2^x than Math.pow(2,x) or a multiplication loop, and is guaranteed to give you an int (or long) result.

It only uses the lowest 5 (or 6) bits of x (i.e. x & 31 (or x & 63)), though, shifting between 0 and 31 (or 63) bits.