interleving two linked list

public ListNode (ListNode l1, ListNode l2) {
    if (l1 == null && l2 == null)
        return null;
    if (l1 == null)
        return l2;
    if (l2 == null)
        return l1;
    Queue<ListNode> q = new LinkedList<>();
    q.offer(l1); q.offer(l2);
    ListNode dummy = new ListNode(-1);
    ListNode ptr = dummy;
    while (!q.isEmpty()) {
        ListNode node = q.poll();
        if (node.next != null)
            q.offer(node.next);
        ptr.next = node;
        ptr = ptr.next;
    }
    return dummy.next;
}