/** * 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) {        boolean iscycle=false;          if (head!=null) {                ListNode temp=head;                while (!iscycle) {                    head=head.next;                    temp.next=temp;                    temp=head;                    if (head==null) {                        iscycle=false;                        break;                    }else {                        if (head.next==head) {                            iscycle=true;                            break;                        }                    }                                    }        }        return iscycle;    }}