set集合的排序

在hibernate的OneToMany的实体关联的时候，one端的set是无序的，可是需要按照顺序来搞的话就比较麻烦了。

下面给出一个例子。

Set<DiaryPicture> diaryPictureSet = growthDiary.getDiaryPictures();
List<DiaryPicture> diaryPictureList = new ArrayList<DiaryPicture>(diaryPictureSet);

/*将list有序排列*/
 Collections.sort(diaryPictureList, new Comparator<DiaryPicture>() {
  public int compare(DiaryPicture arg0, DiaryPicture arg1) {
     eturn arg0.getId().compareTo(arg1.getId()); // 按照id排列
  }
});

想要从小到大就这样，想要从大到小两个参数换一下。