swap node in pairs

public class Solution{
	public ListNode swapPairs(ListNode head){
		if(head == null)
		return null;
		
		ListNode pHead = new ListNode(0);
		pHead.next = head;
		ListNode current = pHead;
		
		while(current.next != null && current.next.next != null){
			ListNode back = current.next;
			ListNode pre = current.next.next;
			
			back.next = pre.next;
			pre.next = back;
			current.next = pre;
			
			current = current.next.next;
		}
		return pHead.next;
	}
}