两个List 去除重复和保留相同的元素

List<String> l1=new ArrayList<String>();l1.add("a");l1.add("b");l1.add("c");List<String> l2=new ArrayList<String>();l2.add("c");l2.add("d");l2.add("e");List<String> l3=new ArrayList<String>();l3.addAll(l1);List<String> l4=l2;//求重复l3.retainAll(l2);//求不重复l4.addAll(l1);l4.removeAll(l3);out.println("l1 = " + l1);out.println("l2 = " + l2);out.println("l3 = " + l3);out.println("l4 = " + l4);