How to find middle element of linked list in one pass in java.

package linkedlist.singly;

public class GetMiddleOfLinkList {

 Node startNode;
 public static void main(String[] args) {
  new GetMiddleOfLinkList();
 }

 public GetMiddleOfLinkList() {
  Node temp1 = new Node(50);
  Node temp2 = new Node(20);
  Node temp3 = new Node(10);
  Node temp4 = new Node(30);
  Node temp5 = new Node(80);
  Node temp6 = new Node(40);
  Node temp7 = new Node(50);
  Node temp8 = new Node(50);

  temp1.setNext(temp2);
  temp2.setNext(temp3);
  temp3.setNext(temp4);
  temp4.setNext(temp5);
  temp5.setNext(temp6);
  temp6.setNext(temp7);
  temp7.setNext(temp8);

  startNode = temp1;
  Node temp = getMiddle(startNode);
  System.out.println(temp.getData());
 }


 private Node getMiddle(Node startNode) {
  if(startNode==null){
   return startNode;
  }

  Node pointer1=startNode;
  Node pointer2=startNode;
  while(pointer2!=null && pointer2.getNext()!=null && pointer2.getNext().getNext()!=null){
   pointer1 = pointer1.getNext();
   pointer2 = pointer2.getNext().getNext();

  }
  return pointer1;
 }

}