java 双向循环链表_Java 用双向循环链表实现 遍历

package day2;

/**

* 构建双向循环链表，实现遍历功能

*/

public class DoubleLB {

public static void main(String[] args) {

DoubleLB doubleLB = new DoubleLB();

doubleLB.creatCicle(100);

doubleLB.doubbl(30);

}

//头结点

Entry head;

void creatCicle(int length){

for(int i= 1; i<=length;i++){

Entry newEntry = new Entry(i*2);

//初始化头结点，把next和pre都指向自己

if(i==1){

head = new Entry(null,null,1);

head.next = head;

head.pre = head;

}else{

/**

* 1 ：新增节点newEntry 的next指向 头结点 head

* 2： newEntry的pre 指向 head的pre。这里头结点的pre可以看做 最后一个节点(便于理解)，也就是要插入新节点的位置 前一个节点

* 3： 插入新节点的位置 前一个节点 的next指向 newEntry

* 4：头结点的pre 指向newEntry。

*/

newEntry.next =head;

newEntry.pre = head.pre;

//head.pre.next = newEntry;//new.pre.next =newEntry

newEntry.pre.next = newEntry;

head.pre = newEntry;

}

}

}

/**

* 这里查看链表上的节点的字段number 是否有等于 输入的number。用到了双向遍历

* @param number

*/

void doubbl(int number){

Entry nextNode = head.next;

Entry preNode = head.pre;

while(nextNode != preNode){

System.out.println("next"+nextNode.getNumber()+": pre"+preNode.getNumber());

if(nextNode.getNumber() == number || preNode.getNumber() ==number){

System.out.println(" find next"+nextNode.getNumber()+": pre"+preNode.getNumber());

return;

}

nextNode=nextNode.next;

preNode=preNode.pre;

}

}

class Entry{

Entry next;

Entry pre;

int number;

public Entry getNext() {

return next;

}

public void setNext(Entry next) {

this.next = next;

}

public Entry getPre() {

return pre;

}

public void setPre(Entry pre) {

this.pre = pre;

}

public int getNumber() {

return number;

}

public void setNumber(int number) {

this.number = number;

}

public Entry(int number) {

this.number = number;

}

public Entry(Entry next, Entry pre, int number) {

this.next = next;

this.pre = pre;

this.number = number;

}

}

}