(Java) 로또 번호 생성

import java.util.TreeSet;

public class Lotto {
    public static void main(String[] args) {
        for (int x : lottoNums())
            System.out.print(x + " ");
    }

    public static TreeSet<Integer> lottoNums() {
        TreeSet<Integer> r = new TreeSet<Integer>();
        while (r.size() < 6)
            r.add((int) (Math.random() * 45 + 1));
        return r;
    }
}