public static <T extends Comparable<? super T>> T max(Collection<T> coll) {
		return isEmpty(coll) ? null : Collections.max(coll);
	}
@Test
	public void maxTest() {
		List<Integer> list = Arrays.asList(1, 2, 3, 4, 5, 6);
		assertEquals((Integer) 6, CollUtil.max(list));
	}