players.java

public static void main(String[] args) {
        class Player {
            Integer id;
            String team;

            public Player(Integer id, String team) {
                this.id = id;
                this.team = team;
            }

            public Integer getId() {
                return id;
            }

            public String getTeam() {
                return team;
            }

            @Override
            public String toString() {
                return "{" + "player.id=" + id + ", player.team='" + team + '\'' + '}';
            }
        }

        final List<Player> players =
                Arrays
                .asList(new Player(1, "palmeiras"),
                        new Player(2, "palmeiras"),
                        new Player(3, "sp"),
                        new Player(4, "palmeiras"),
                        new Player(5, "palmeiras"),
                        new Player(6, "sp"),
                        new Player(7, "sem time"),
                        new Player(8, "sem time"),
                        new Player(9, "sp"));

        final Map<String, List<Player>> teams = players.stream().collect(Collectors.groupingBy(p -> p.getTeam()));

        System.out.println("sem time: " + teams.get("sem time"));
        System.out.println("palmeiras: " + teams.get("palmeiras"));
        System.out.println("sp: " + teams.get("sp"));
    }