去掉两个集合中重复的元素

eg:

   List<String> list1 = new ArrayList<String>();

   list1.add("A");

   list1.add("B");

   List<String> list2 = new ArrayList<String>();

   list2.add("A");

   list2.add("C");

   for(String str1 : list1)

       {

            int count = 0;

            for(String str2 : list2)

                {

                      if(str1.equals(str2))

                        {

                              count++;

                         }

                }

             if(count >= 1)

               {

                      list2.remove(str1);

               }

       }