Common elements in two lists

Question

I have two ArrayList objects with three integers each. I want to find a way to return the common elements of the two lists. Has anybody an idea how I can achiev

Answer 1

            List lista =new ArrayList();
            List listb =new ArrayList();

            lista.add("Isabella");
            lista.add("Angelina");
            lista.add("Pille");
            lista.add("Hazem");

            listb.add("Isabella");
            listb.add("Angelina");
            listb.add("Bianca");

            // Create an aplusb list which will contain both list (list1 and list2) in which common element will occur twice 
            List listapluslistb =new ArrayList(lista);    
            listapluslistb.addAll(listb);

            // Create an aunionb set which will contain both list (list1 and list2) in which common element will occur once
            Set listaunionlistb =new HashSet(lista);
            listaunionlistb.addAll(listb);

            for(String s:listaunionlistb)
            {
                listapluslistb.remove(s);
            }
            System.out.println(listapluslistb);