import java.util.*;
import java.util.stream.*;
public class MyClass {
public static void main(String args[]) {
Set<Integer> set = new HashSet<>(Arrays.asList(1, 2, 3, 4, 5, 6));
int[] arr = set.stream().mapToInt(Integer::intValue).toArray();
System.out.println(Arrays.toString(arr));
}
}
/*
run:
[1, 2, 3, 4, 5, 6]
*/