leetcode 24. Exchange the nodes in the linked list in pairs

class Solution {
    
    public ListNode swapPairs(ListNode head) {
    
        ListNode dummyHead = new ListNode();
        dummyHead.next = head;
        ListNode temp = dummyHead;
        while (temp.next != null && temp.next.next != null) {
    
            ListNode node1 = temp.next;
            ListNode node2 = temp.next.next;
            temp.next = node2;
            node1.next = node2.next;
            node2.next = node1;
            temp = node1;
        }
        return dummyHead.next;
    }
}