程序里有几个注释的地方还是需要特别注意的，根据单链表自己的逻辑来写一遍双向链表，可能有几个细节处理的不到位。

package DataStructures.LinkedList;public class DoubleLinkedListDemo {public static void main(String []args){System.out.println("双向链表的测试");//先创建节点HeroNode2 hero1 = new HeroNode2(1, "宋江", "及时雨");HeroNode2 hero2 = new HeroNode2(2, "卢俊义", "玉麒麟");HeroNode2 hero3 = new HeroNode2(3, "吴用", "智多星");HeroNode2 hero4 = new HeroNode2(4, "林冲", "豹子头");//创建一个双向链表DoubleLinkedList doubleLinkedList = new DoubleLinkedList();//添加节点doubleLinkedList.add(hero1);doubleLinkedList.add(hero2);doubleLinkedList.add(hero3);doubleLinkedList.add(hero4);doubleLinkedList.list();HeroNode2 newHeroNode = new HeroNode2(4,"公孙胜","入云龙");doubleLinkedList.updata(newHeroNode);doubleLinkedList.list();doubleLinkedList.delete(1);doubleLinkedList.list();}
}
class DoubleLinkedList{private HeroNode2 head = new HeroNode2(0,"","");public HeroNode2 getHead() {return head;}//删除一个节点//说明//对于双向链表，直接找到这个节点，进行自我删除public void delete(int no){if (head.next == null){System.out.println("链表为空，无法删除");}//这里要加next，因为0是不能删除的HeroNode2 temp = head.next;boolean flag = false;//这里现在是用temp本身来判断while (temp != null){if (temp.no == no){flag = true;break;}temp = temp.next;}if (flag){temp.pre.next = temp.next;//注意：：这里会有问题？？？//因为如果删除的节点是最后一个节点，下面这句话加上了，会出现空指针异常if (temp.next != null) {temp.next.pre = temp.pre;}System.out.println("节点删除成功\n");}else {System.out.printf("没找到编号为 %d 的节点！删除失败\n",no);}}//修改一个节点的内容public void updata(HeroNode2 heroNode){if (head.next == null){System.out.println("链表为空位，无法修改");return;}//这里要用next，因为更改的时候头结点不能找HeroNode2 temp = head.next;boolean flag = false;while(true){if (temp == null){break;}if (temp.no == heroNode.no){flag = true;break;}temp = temp.next;}if (flag){temp.name = heroNode.name;temp.nickname = heroNode.nickname;}else {System.out.printf("没找到 编号为 %d 的节点\n",heroNode.no);}}//添加节点public void add(HeroNode2 newHeroNode){HeroNode2 temp = head;while(true){if (temp.next == null){break;}temp = temp.next;}//while退出后temp就是链表最后节点//形成双向链表temp.next = newHeroNode;newHeroNode.pre = temp;}//遍历输出public void list(){if (head.next == null){System.out.println("链表为空");return;}//这里要加next要不然打印会把头结点打印出来HeroNode2 temp = head.next;while (temp != null){System.out.println(temp);temp = temp.next;}}}class HeroNode2{public int no;public String name;public String nickname;public HeroNode2 next; //指向下一个节点public HeroNode2 pre; //指向前一个节点public HeroNode2(int no, String name, String nickname) {this.no = no;this.name = name;this.nickname = nickname;}@Overridepublic String toString() {return "HeroNode2{" +"no=" + no +", name='" + name + '\'' +", nickname='" + nickname + '\'' +'}';}
}

加一个添加的时候根据no排序

//添加节点并根据no有序public void addByOrder(HeroNode2 newHeroNode){HeroNode2 temp = head;boolean flag = false;while (true){if (temp.next == null){break;}if (temp.next.no > newHeroNode.no){break;}else if (temp.next.no == newHeroNode.no){flag = true;break;}temp = temp.next;}if (flag){System.out.printf("编号 %d 已存在,不能添加\n",newHeroNode.no);}else {//这里注意不要写反了，先写if这里，再写剩下两个，要不然就形成了一个环状，这里找了好久bugif (temp.next != null) {temp.next.pre = newHeroNode;newHeroNode.next = temp.next;}temp.next = newHeroNode;newHeroNode.pre = temp;}}

测试

doubleLinkedList.addByOrder(hero1);
doubleLinkedList.addByOrder(hero4);
doubleLinkedList.addByOrder(hero2);
doubleLinkedList.addByOrder(hero3);doubleLinkedList.list();

结果：双向链表的测试
HeroNode2{no=1, name='宋江', nickname='及时雨'}
HeroNode2{no=2, name='卢俊义', nickname='玉麒麟'}
HeroNode2{no=3, name='吴用', nickname='智多星'}
HeroNode2{no=4, name='林冲', nickname='豹子头'}