List转set_JAVA数组转set内容不一致

//获取帖子集合
List<Post> postList=postService.pagePost(req);

//获取所有帖子的ids
list<Long> ids=postList.stream().map(x -> x.getId()).collect(Collectors.toList());

//获取所有点赞帖子的ids
List<Long> likeIds = likeService.selectLikesByIds(ids).stream().map(o ->o.getTargetId()).collect(Collectors.toList());

//list转set(重点)
Set<Long> likeSet = new HashSet<>(likeIds);

//将点赞状态set进返回体
postResponse.setLikeStatue(likeSet.contains(postResponse.getId()));

//第二种list转set的方法
Set<Long> likeSet = likeService.selectLikesByIds(ids).stream().map(o ->o.getTargetId()).collect(Collectors.toSet());

//Set转化成List

//方法一
Set<String> set = new HashSet<String>();
set.add("mmmmmm");
set.add("nnnnnn");
set.add("ssssss");
List<String> list = new ArrayList<String>(set);

//方法二，使用迭代器
Set<String> set = new HashSet<String>();
set.add("aaaaa");
set.add("bbbbb");
set.add("ccccc");
List<String> list = new ArrayList<String>();
Iterator it=set.iterator();
while(it.hasNext())
{
    list.add(it.next());
}