Question

I’ve got a public List<FriendProfile> friends = new ArrayList<FriendProfile>();. I initialize the friends list by reading the information from the server. The FriendProfile object contains a int called private int userPosition;

Once the friends list has been initialized, I would like to sort the friends list by having the FriendProfile object with the highest userPosition at index 0 of the list and then sort by accordingly, index 1 with the second highest userPosition …

I guess I could write an sorting algorithm, yet I’m looking for prewritten code (maybe the JDK has some methods to offer?)

Help is appreciated!

Answer 1

Use Collections.sort() and specify a Comparator:

Collections.sort(friends,
                 new Comparator<FriendProfile>()
                 {
                     public int compare(FriendProfile o1,
                                        FriendProfile o2)
                     {
                         if (o1.getUserPosition() ==
                                 o2.getUserPosition())
                         {
                             return 0;
                         }
                         else if (o1.getUserPosition() <
                                      o2.getUserPosition())
                         {
                             return -1;
                         }
                         return 1;
                     }
                 });

or have FriendProfile implement Comparable<FriendProfile>.