Does HashSet do the sort job internal?

My Set is sometimes sorted, and sometimes not.

Here is the example:

public class SetOfInteger {
    public static void main(String[] args) {
        Random rand = new Random(47);
        Set<Integer> intset = new HashSet<>();
        for (int i = 0; i < 10; i++) {
            int j = rand.nextInt(30);
            System.out.print(j + " ");
            intset.add(j);
        }
        System.out.println();
        System.out.println(intset);
    }
}

The result shows that the set is not sorted.

8 5 13 11 1 29 28 20 12 7 
[1, 20, 5, 7, 8, 11, 12, 29, 28, 13]

When I change the termination expression to i < 20 in the for statement, the result shows that the set become sorted.

8 5 13 11 1 29 28 20 12 7 18 18 21 19 29 28 28 1 20 28 
[1, 5, 7, 8, 11, 12, 13, 19, 18, 21, 20, 29, 28]

It is so strange, is it? I just don't know how to explain it, and I need some help, Thank you very much.