List<Set<Integer>> l1 = new ArrayList<Set<Integer>>();
Set<Integer> s1 = new HashSet<Integer>(Arrays.asList(new Integer[]{1,2}));
Set<Integer> s2 = new HashSet<Integer>(Arrays.asList(new Integer[]{3,4}));
l1.add(s1);
l1.add(s2);

List<Set<Integer>> l2 = new ArrayList<Set<Integer>>();
Set<Integer> s3 = new HashSet<Integer>(Arrays.asList(new Integer[]{1,3}));
Set<Integer> s4 = new HashSet<Integer>(Arrays.asList(new Integer[]{2,4}));
l2.add(s3);
l2.add(s4);

for (Set<Integer> ls1 : l1) {
    for (Set<Integer> ls2 : l2) {
        Set<Integer> ts = new HashSet<Integer>(ls1);
        ts.retainAll(ls2);
        if (ts.size() > 0) {
            System.out.println("has same element:");
            System.out.println(ts);
        }
    }
}