Check if a linkedlist has a cycle

HasCycle.java

package com.interviewbytes.linkedlists;

public class HasCycle {

    public boolean hasCycle(ListNode head) {

        ListNode slow = head;
        ListNode fast = head;

        while (fast != null && fast.next != null) {
            fast = fast.next.next;
            slow = slow.next;

            if (slow == fast) return true;
        }

        return false;
    }
}

ListNode.java

package com.interviewbytes.linkedlists;


public class ListNode {
    int val;
    ListNode next;

    ListNode(int x) {
        val = x;
    }
}