Grouping of 5 items sorted by criteria

Question

I want to make a java application, which is addressed for an esports competition. Specifically this application will be for a teamspeak server.

I want users on a channel to be sorted into groups of 5 (they will be identified by a uniqid and a number representing the skill level).

Thus, when 5 users are between skill levels 1 - 3 to be placed in one group, the next ones in another group (each of 5), and until that list / map will no longer be able to be made groups of 5.

Can you help me with an idea? I know how to get the uniqid from the teamspeak server, as well as the skill level, but I don't know how to randomly group them and meet that skill level condition.

I tried a hashmap but it failed.

HashMap<Integer, Integer> teams = new HashMap<>();
                    for(Client c : api.getClients()){
                        if(c.getChannelId() == 2170){
                            if(api.getChannelByNameExact("[LOBBY] Cauta echipa",true).getTotalClients() >= 5) {
                                if (c.isInServerGroup(Integer.parseInt(Configuration.info().getProperty("SILVER1")))) {
                                    teams.put(c.getId(), 1);
                                }
                                if (c.isInServerGroup(Integer.parseInt(Configuration.info().getProperty("SILVER2")))) {
                                    teams.put(c.getId(), 2);
                                }
                                if (c.isInServerGroup(Integer.parseInt(Configuration.info().getProperty("SILVER3")))) {
                                    teams.put(c.getId(), 3);
                                }
                                if (c.isInServerGroup(Integer.parseInt(Configuration.info().getProperty("SILVER4")))) {
                                    teams.put(c.getId(), 4);
                                }
                                if (c.isInServerGroup(Integer.parseInt(Configuration.info().getProperty("SILVERE")))) {
                                    teams.put(c.getId(), 5);
                                }
                                while(teams.size() >= 5){
                                    teams.forEach((key, value) -> {
                                        System.out.println("Key : " + key + " Value : " +value);
                                        if(value > 1 && value < 5){
                                            teams.
                                        }
                                    });
                                }
                                teams.clear();
                            }
                    }
                }

Exemple:

If on a teamspeak channel there are 20 people with skill level in 1 lvl -18 lvl, the robot will build teams of 5 members with similar skill level (with a margin of + - 1 level). For example, if I have skill level 5, and on the channel there are at least 4 people with skill level between 3-5, the 5 people (including myself) will be added to a list or array or whatever. After we made the team of 5 people, the program will continue to run and form teams of 5 people with similar skill level, until it will no longer be possible (there will be no 5 people in the main room).

Answer 1

1. On my mind you should divide on two groups(ArrayLists) hightlevel and lowlevel, for this create function and check skills level(skills>3)=>hight else=>low;
2. After create HashMap team; where keys - ids; and value - numbers of group;
3. With operator for and function MathRandom complete first group; value++; Continue while you have available people.
4. Change value +1(it will be next group) complete HashMap with next Array, using MathRandom(); This is working, if ids - Integer and unique. of course you have to delete from Array element after putting in the map

Also you can try to manage with databases MongoDB: 1.Create two datas: high and low level 2. With Pagebale create page items on page 5; number of page will be your group number. Use method unsorted