1 　　　　　HashSet<Integer> hashSet = new HashSet<Integer>(); 2         for (int i = resultDoctorDetails.size() - 1; i >= 0; --i) { 3             ResultDoctorDetail temp = resultDoctorDetails.get(i); 4             if (!hashSet.contains(temp.getUserId())) { 5                 hashSet.add(temp.getUserId()); 6             } else { 7                 resultDoctorDetails.remove(i); 8             } 9         }