Linked List Cycle - LeetCode

Given a linked list, determine if it has a cycle in it.

Follow up:

Can you solve it without using extra space?

/**
* Definition for singly-linked list.
* class ListNode {
* int val;
* ListNode next;
* ListNode(int x) {
* val = x;
* next = null;
* }
* }
*/
public class Solution {
public boolean hasCycle(ListNode head) {
if(head == null)
return false;

ListNode current = head;
ListNode current2 = current.next;
while(current2 != null){
if((current!=null)&&(current2.next!=null)){
current = current.next;
current2 = current2.next.next;
}
else{
return false;
}
if(current == current2)
return true;

}
return false;
}
}