java8 中List根据某一字段 去重 【延伸介绍另外一种方式】

       //去重用户名称
       List<User> userList = new ArrayList<User>();
       userList =  userList.stream().collect(
            Collectors.collectingAndThen(Collectors.toCollection(
                () -> new TreeSet<>(Comparator.comparing(User::getUserName))), ArrayList::new));

public static void main(String[] args) {
    List<String> stringList = new ArrayList<String>();
    //电话号码
    String getContactorPhoneNum1="12345678910";
    String getContactorPhoneNum2="12345678911";
    String getContactorPhoneNum3="12345678910";
    String getContactorPhoneNum4="12345678911";
    //多次插入到集合
    stringList.add(getContactorPhoneNum1);
    stringList.add(getContactorPhoneNum2);
    stringList.add(getContactorPhoneNum3);
    stringList.add(getContactorPhoneNum4);
    //进行去重
    HashSet<String> hs = new HashSet<String>(stringList);   
    stringList.clear();   
    stringList.addAll(hs);
        //打印到控制台
    System.out.println(stringList);
}