Java8 List object deduplication (deduplication according to object genus)

/**
*  方式一：去重后对象在集合的顺序变化
*  List对象去重，按照对象的某个字段去重，返回去重后新的对象集合
* 
**/
public static void main(String[] args) {

    List<Student> list = new ArrayList<>();
    list.add(Student.builder().stuNo("23444").name("test").build());
    list.add(Student.builder().stuNo("11111").name("test2").build());
    list.add(Student.builder().stuNo("6666").name("test3").build());
    list.add(Student.builder().stuNo("11111").name("test5").build());
	
	// 方式一：单属性去重
    List<Student> unique1 = list.stream().collect(Collectors.collectingAndThen(Collectors.toCollection(() -> new TreeSet<>(Comparator.comparing(Student::getName))), ArrayList::new));

	// 方式一：多属性去重
    List<Student> unique1 = list.stream().collect(Collectors.collectingAndThen(Collectors.toCollection(() -> new TreeSet<>(Comparator.comparing(Student::getName).thenComparing(Test::getStuNo))), ArrayList::new));



}

/**
*  方式二：去重后对象在集合中顺序跟原集合一样
*  List对象去重，按照对象的某个字段去重，返回去重后新的对象集合
*  使用方法：用Stream接口的 filter()接收为参数
* */
 public static <T> Predicate<T> distinctByKey(Function<? super T, ?> keyExtractor) {
    Map<Object,Boolean> seen = new ConcurrentHashMap<>();
    return t -> seen.putIfAbsent(keyExtractor.apply(t), Boolean.TRUE) == null;
 }   
    // filter单属性去重
    System.out.println(JSONObject.toJSONString(collect.stream().filter(distinctByKey(Test::getAid)).collect(Collectors.toList())));
    // filter多属性去重
    System.out.println(JSONObject.toJSONString(collect.stream().filter(distinctByKey(test -> Stream.of(test.getAid(),test.getUid()).toArray())).collect(Collectors.toList())));