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双向链表也叫双链表，是链表的一种，它的每个数据结点中都有两个指针，分别指向直接后继和直接前驱。所以，从双向链表中的任意一个结点开始，都可以很方便地访问它的前驱结点和后继结点。

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节点类

//节点类
class DNode {//数据域public int id;public String name;//指针域public DNode next; //指向后一个节点public DNode pre; //指向前一个节点public DNode(int id, String name) {this.id = id;this.name = name;}@Overridepublic String toString() {return "Node{" +"id=" + id +", name='" + name + '\'' +'}';}
}

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链表类

//链表类（管理节点）
class DoubleLinkedList {//头节点private DNode head = new DNode(0,null);//展示链表public void list(){if (head.next == null){System.out.println("链表为空！");return;}DNode temp = head.next;while (true){if (temp == null){break;}System.out.println(temp);temp = temp.next;}}//增（在链表尾部）public void add1(DNode newNode){//因为头节点不能动，因此要一个辅助变量tempDNode temp = head;//遍历找到最后while (true){if (temp.next == null){break;}temp = temp.next;}//当退出while就意味着找到最后一个节点了temp.next = newNode;newNode.pre = temp;}//删(根据id匹配删除)public void remove(int id){if (head.next == null){System.out.println("链表为空!");return;}DNode temp = head.next;boolean flag = false; //用来标记是否找到对应id的节点while (true){if (temp == null){break;}if (temp.id == id){ //找到要删除节点的前一个节点flag = true;break;}temp = temp.next;}if (flag){temp.pre.next = temp.next; //该节点前一个节点的next指向该节点后一个节点if (temp.next != null){ //只有当删除的节点不是最后一个节点时才需要执行下面，否则空指针异常temp.next.pre = temp.pre; //该节点后一个节点的pre指向该节点前一个节点}}else {System.out.println("没有找到要删除的节点，删除失败!");}}//改（根据id匹配要修改的节点）public void update(int id,String name){if (head.next == null){System.out.println("链表为空！");return;}DNode temp = head.next;boolean flag = false; //用来标记是否找到对应id的节点while (true){if (temp == null){break;}if (temp.id == id){flag = true;break;}temp = temp.next;}if (flag){temp.name = name;}else {System.out.println("没有找到要修改的节点，修改失败！");}}//查（根据id匹配）public DNode show(int id){if (head.next == null){System.out.println("链表为空！");return null;}DNode temp = head.next;boolean flag = false;while (true){if (temp == null){break;}if (temp.id == id){flag = true;break;}temp = temp.next;}if (flag){return temp;}else {System.out.println("没有找到要查找的节点，查找失败！");return null;}}}

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测试类

/*** @Author: Yeman* @Date: 2021-10-15-20:20* @Description:*/
public class DoubleLinkedListTest {public static void main(String[] args) {DoubleLinkedList doubleLinkedList = new DoubleLinkedList();DNode node1 = new DNode(1, "阿兰");DNode node2 = new DNode(2, "洛国富");DNode node3 = new DNode(3, "艾克森");doubleLinkedList.add1(node1);doubleLinkedList.add1(node2);doubleLinkedList.add1(node3);doubleLinkedList.list();//        doubleLinkedList.remove(3); //删
//        doubleLinkedList.update(3,"张玉宁"); //改
//        System.out.println(doubleLinkedList.show(3)); //查doubleLinkedList.list();}
}