java 链表实现（测试是否有环）

 package com.bb.bbs;import java.util.ArrayList;/** * 节点类：用于保存链表中的节点 */class Node{Node next;String data;//下一节点public static int maxs = 0;//getSize() 最大数量public static int maxg = 0;//getArray()最大数量public static int maxp = 0;//printNode()打印节点最大数量public static int maxc = 0;//contains()最大数量         /**          * 带参数的构造方法          */public Node(String data){this.data = data;}         /**          * 在当前节点上增加一个节点          */public void addNode(Node node){if(this.next==null){this.next = node;}else{this.next.addNode(node);}}         /**          * 从root开始寻找，目的是移除一个节点          */public boolean removeNode(Node previous,String data){if(this.data.equals(data)){previous.next = this.next;return true;}else{return this.next.removeNode(this, data);}}         /**          * 是否包含节点          */public boolean contains(String data){maxc++;if(maxc==10){return false;}if(this.data.equals(data)){return true;}if(this.next == null){return false;}else{return this.next.contains(data);}}         /**          * 打印一个节点          */public void printNode(){maxp++;if(maxp==10){return;}if(this.next!=null){System.out.println(this.next.data);this.next.printNode();}}         /**          * 查找并返回一个节点          */public Node findNode(String data){if(this.data.equals(data)){return this;}else{return this.next.findNode(data);}}         /**          * 得到链表大小          */ public int getSize(int currentNum){maxs++;if(maxs==10){return 10;}if(this!=null){currentNum++;}if(this.next!=null){return this.next.getSize(currentNum);}else{return currentNum;}}         /**          * 将节点里所有值封装到一个ArrayList中          */public void getArray(ArrayList tArrayList){maxg++;if(maxg==10){return;}tArrayList.add(this.data);if(this.next!=null){this.next.getArray(tArrayList);}}}/** * 链表类 */class Link{Node root;public void add(String data){if(data==null){return;}if(root ==null){root = new Node(data);}else{root.addNode(new Node(data));}}public boolean remove(String data){if(root.data.equals(data)){root = root.next;return true;}else{return this.root.next.removeNode(root, data);}}public boolean contains(String data){if(root.data.equals(data)){return true;}else{return root.contains(data);}}public void print(){if(root!=null){System.out.println(root.data);root.printNode();}}public Node find(String data){if(contains(data)){if(this.root.data.equals(data)){return root;}else{return root.findNode(data);}}return null;}public int size(){if(root.next ==null){return 1;}else{return root.next.getSize(1);}}public void getArray(ArrayList tArrayList){if(root!=null){tArrayList.add(root.data);}if(root.next!=null){root.next.getArray(tArrayList);}}}/**  * 测试入口 */public class LinkList {public static void main(String args[]){                  //1、增加链表节点Link tLink = new Link();tLink.add("A");tLink.add("B");tLink.add("C");tLink.add("D");                  tLink.print();//2、形成环 A->B->C->A->B->C->A->B->C...... 无限循环Node fnodeA = tLink.find("A");Node fnodeC = tLink.find("C");//如果有一个为空if(fnodeA==null || fnodeC==null){System.out.println("没有找到元素！");}else{System.out.println("已找到元素！");fnodeC.next = fnodeA;//出现环}int linksize = tLink.size();System.out.println("链表大小为："+linksize);ArrayList tArrayList = new ArrayList();tLink.getArray(tArrayList);for(Object o : tArrayList){String str = o.toString();System.out.println(str);}boolean flag = false;int circleLen = 0;//检验 "环" 是否存在for(int i=0;i<linksize;i++){for(int j=i;j<linksize;j++){if(j!=i && tArrayList.get(j).toString().equals(tArrayList.get(i).toString())){circleLen = j-i;flag = true;break;}}}if(flag){System.out.println("有环,环的长度为:"+circleLen);}else{System.out.println("无环");}                  //3、移除一个节点tLink.remove("B");                  //4、移除后打印所有节点tLink.print();                  //打印链表长度tLink.root.maxs = 0;System.out.println(tLink.size());                  //5、是否包含有C这个节点System.out.println(tLink.contains("C"));}}