import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

public class SetDemo {

    public static void main(String[] args) {
        List<Integer> listNumbers = Arrays.asList(3, 9, 1, 4, 7, 2, 5, 3, 8, 9, 1, 3, 8, 6);
        System.out.println(listNumbers);
        Set<Integer> uniqueNumbers = new HashSet<>(listNumbers);
        System.out.println(uniqueNumbers);
    }
}