Method for deduplication of object collection

Sometimes we have such a requirement. There are several objects in a collection whose data is repeated. We only want to take the ones that are not repeated. We can do it by the following methods

//This is about deduplication through the tDeptId fieldprivate static  Predicate distinctByVariable(Function keyExtractor){HashMap map = new HashMap<>();return t -> map.putIfAbsent(keyExtractor.apply(t), Boolean.TRUE) == null;}public HttpResult updateUserInfo(@RequestBody UpdateUserParam updateUserParam) {List collect3 = collect.stream().filter(distinctByVariable(u -> u.getDeptId())).collect(Collectors.toList());}