Hello I am trying to pass to my jsp page two sorted Lists which I get from the database like that
@RequestMapping(value = "/sortDate", method= RequestMethod.GET)
public void sortedLists(Model model, HttpSession session){
List<Song> songsByDate;
try {
songsByDate = SongDAO.getInstance().getAllSongs();
Collections.sort(songsByDate, new UploadTimeComparator());
session.setAttribute("songs", songsByDate);
/////////////////////////////////
List<Song> songsByLikes;
try {
songsByLikes = SongDAO.getInstance().getAllSongs();
Collections.sort(songsByLikes, new LikesComparator());
session.setAttribute("songs2", songsByLikes);
}}}
However the problem is since I use getInstance() , songs and songs2 are the same Lists sorted by Likes,how can I overcome this problem?
You need to copy each "all songs" list to a new array list, which you can then proceed to sort.
So:
List<Song> songsByDate = new ArrayList<>( SongDAO.getInstance().getAllSongs() );
Collections.sort( songsByDate, new UploadTimeComparator() );
List<Song> songsByLikes = new ArrayList<>( SongDAO.getInstance().getAllSongs() );
Collections.sort( songsByLikes, new LikesComparator() );