package org.myorg; public class Test{ public static boolean isExsitLoop(SingleList a) {  Node<T> slow = a.head;  Node<T> fast = a.head; while (fast != null && fast.next != null) {        slow = slow.next;        fast = fast.next.next;             if (slow == fast)                return true;       }        return false;    }   public static void main(String args[]){     SingleList list = new SingleList();     for(int i=0;i<100;i++){       list.add(i); } System.out.print(SingleList.isExistingLoop(list)); } }

package org.myorg; public class Node{     public Object data; //节点存储的数据对象     public Node next; //指向下一个节点的引用     public Node(Object value){         this.data = value;    }     public Node(){ 　　　　　　this.data = null;           this.next = null;    } }

package org.myorg; public class SingleList{     private int size;     private Node head;     private void init(){         this.size = 0;         this.head = new Node();      }    public SingleList(){          init();    }   public boolean contains(Object value){    boolean flag = false;    Node p = head.next;    while(p!=null){         if(value.equals(p.data)){            flag = true;            break;        }else(             p = p.next;            )      }     return flag;   }     public boolean add(Object value){      if(contains(value))          return false;      else{      Node p = new Node(value);      p.next=head.next;      head.next = p;      size++; }   return true;     } }