public static boolean isPowerOfTwo(long n) {
		return (n > 0) && ((n & (n - 1)) == 0);
	}
@Test
	public void isPowerOfTwoTest() {
		assertFalse(NumberUtil.isPowerOfTwo(-1));
		assertTrue(NumberUtil.isPowerOfTwo(16));
		assertTrue(NumberUtil.isPowerOfTwo(65536));
		assertTrue(NumberUtil.isPowerOfTwo(1));
		assertFalse(NumberUtil.isPowerOfTwo(17));
	}