public static <E> Set<E> disjointView(final Set<? extends E> set1, final Set<? extends E> set2) {
		return Sets.symmetricDifference(set1, set2);
	}
public static < E > Set < E > disjointView ( final Set < ? extends E > set1 , final Set < ? extends E > set2 ) { return Sets . symmetricDifference ( set1 , set2 ) ; }
set1, set2的补集（在set1或set2中，但不在交集中的对象，又叫反交集）的只读view，不复制产生新的Set对象.

如果尝试写入该View会抛出UnsupportedOperationException