Determine if num is a power of two in java?

Question

Possible Duplicate:
How to check if a number is a power of 2

How could I write a method that would return true if passed in the value 2, 4, 8, 32, 64, and so on?

Answer 1

This is probably the best way:

((value & -value) == value)

Answer 2

Might want to look at this if you need a fast algorithm:

http://en.wikipedia.org/wiki/Power_of_two#Fast_algorithm_to_check_if_a_positive_number_is_a_power_of_two