Android : Collections.sort không chạy

Mọi người xem giúp mình đoạn code này với, đoạn Collections.sort không chạy
private void xulylaydiem(){

ten1 = luutru.getString("ten1", "-");
ten2 = luutru.getString("ten2", "-");
ten3 = luutru.getString("ten3", "-");
ten4 = luutru.getString("ten4", "-");
ten5 = luutru.getString("ten5", "-");
ten6 = luutru.getString("ten6", "-");
ten7 = luutru.getString("ten7", "-");
ten8 = luutru.getString("ten8", "-");

ngay1 = luutru.getString("ngay1", "-");
ngay2 = luutru.getString("ngay2", "-");
ngay3 = luutru.getString("ngay3", "-");
ngay4 = luutru.getString("ngay4", "-");
ngay5 = luutru.getString("ngay5", "-");
ngay6 = luutru.getString("ngay6", "-");
ngay7 = luutru.getString("ngay7", "-");
ngay8 = luutru.getString("ngay8", "-");

diem1 = luutru.getString("diem1", "0");
diem2 = luutru.getString("diem2", "0");
diem3 = luutru.getString("diem3", "0");
diem4 = luutru.getString("diem4", "0");
diem5 = luutru.getString("diem5", "0");
diem6 = luutru.getString("diem6", "0");
diem7 = luutru.getString("diem7", "0");
diem8 = luutru.getString("diem8", "0");
player1 = new Player(ten1,Integer.parseInt(diem1),ngay1);
player2 = new Player(ten2,Integer.parseInt(diem2),ngay2);
player3 = new Player(ten3,Integer.parseInt(diem3),ngay3);
player4 = new Player(ten4,Integer.parseInt(diem4),ngay4);
player5 = new Player(ten5,Integer.parseInt(diem5),ngay5);
player6 = new Player(ten6,Integer.parseInt(diem6),ngay6);
player7 = new Player(ten7,Integer.parseInt(diem7),ngay7);
player8 = new Player(ten8,Integer.parseInt(diem8),ngay8);
player9 = new Player(name,score,"_");


player = new ArrayList<>();
player.add(player1);
player.add(player2);
player.add(player3);
player.add(player4);
player.add(player5);
player.add(player6);
player.add(player7);
player.add(player8);
player.add(player9);

Collections.sort(player, new Comparator<Player>() {
    @Override
    public int compare(Player sv1, Player sv2) {
        if (sv1.getDiem() < sv2.getDiem()) {
                return -1;
        } else if (sv1.getDiem() == sv2.getDiem()) {
                return 0;
        } else {
                return 1;
        }

    }
});

}