4，java数据结构和算法：双向链表 ，有序添加，正向遍历，反向遍历， 增删改查

直接上代码

//节点
class HeroNodeD{
    int no;
    String name;
    String nickName;
    HeroNodeD pre;//前一节点
    HeroNodeD next;//后一节点

    public HeroNodeD(int no, String name, String nickName) {
        this.no = no;
        this.name = name;
        this.nickName = nickName;
    }

    @Override
    public String toString() {
        return "HeroNodeD{" +
                "no=" + no +
                ", name='" + name + '\'' +
                ", nickName='" + nickName + '\'' +
                '}';
    }
}

双向链表：

//双向链表
class DoublleLinkList{
    public HeroNodeD head = new HeroNodeD(0,"","");

    public void setHead(HeroNodeD head) {
        this.head = head;
    }

    //0, 获取头结点
    public HeroNodeD getHead(){
        return head;
    }
    //1, 获取尾结点
    public HeroNodeD getLastNode(){
        HeroNodeD temp = head;
        while(true){
            if(temp.next == null){
                break;//尾节点
            }
            temp = temp.next;
        }
        return temp;
    }
    //2, 添加(添加节点到链表的最后面)
    public void add(HeroNodeD node){
        HeroNodeD temp = head;
        while(true){
            if(temp.next == null){
                break;//尾节点
            }
            temp = temp.next;
        }
        //循环结束后,此时temp就是尾节点
        temp.next = node;
        node.pre = temp;
    }
    //3, 添加(根据节点的no(排名)的大小, 有序添加)
    public void addByNo(HeroNodeD node){
        HeroNodeD temp = head;
        while (true) {
            if(temp.next == null){
                break;//链表尾部就跳出
            }
            if(temp.next.no > node.no){
                break;
            }
            temp = temp.next;
        }
        //循环结束, 说明temp的下一节点, 就是node的插入位置
        node.next = temp.next;//设置node和 temp.next的后节点
        temp.next.pre = node;//设置node和 temp.next的 前节点

        node.pre = temp;//设置temp 和 node的 前节点
        temp.next = node;//设置temp 和 node的 后节点
    }
    //4, 双向链表的 遍历,从前向后遍历
    public void showBeginToEnd(){
        HeroNodeD temp = head;
        while(true){
            if(temp.next == null){
                break;
            }
            System.out.println(temp);
            temp = temp.next;
        }
        System.out.println(temp);
    }
    //5:从后向前遍历
    public void showEndToBegin(){
        //获取尾节点
        HeroNodeD temp = getLastNode();
        while(true){
            if(temp.pre == null){
                break;
            }
            System.out.println(temp);
            temp = temp.pre;
        }
        System.out.println(temp);
    }
    //6, 链表的长度// 头节点不计入长度
    public int length(){
        HeroNodeD temp = head;
        int count=0;
        while(true){
            if(temp.next == null){
                break;
            }
            count++;
            temp = temp.next;
        }
        return count;
    }
    //7, 删除第n个节点
    public void delNode(int n){
        int count = 0;
        boolean flag = false;
        HeroNodeD temp = head.next;
        while (temp != null) {
            count++;
            if (count == n) {
                flag = true;
                break;
            }
            temp = temp.next;
        }
        if(flag){
            //跳出循环,说明找到这个节点, 删除该节点
            temp.pre.next = temp.next;
            temp.next.pre = temp.pre;
        }else{
            System.out.println("不存在这个节点");
        }

    }
    //8, 更改某个节点
    public void updateNode(int n, HeroNodeD node){
        boolean flag = false;
        int count = 0;
        HeroNodeD temp = head.next;
        while (temp != null) {
            if(temp.next == null){
                break;
            }
            count++;
            if(count == n){
                flag = true;
                break;
            }
            temp = temp.next;
        }

        if(flag){
            //更换这个节点
            temp.pre.next = node;
            node.pre = temp.pre;

            node.next = temp.next;
            temp.next.pre = node;
        }else{
            System.out.println("不存在这个节点");
        }
    }
}

测试代码：

    public static void main(String[] args){
        DoublleLinkList doublelink = new DoublleLinkList();
        HeroNodeD node1 = new HeroNodeD(1, "宋江", "及时雨");
        HeroNodeD node2 = new HeroNodeD(2, "吴用", "神算子");
        HeroNodeD node3 = new HeroNodeD(3, "卢俊义", "玉麒麟");
        HeroNodeD node4 = new HeroNodeD(4, "武松", "打老虎");
        HeroNodeD node5 = new HeroNodeD(5, "吕财", "打老虎");

        doublelink.add(node1);
        doublelink.add(node3);
        doublelink.addByNo(node2);//有序添加

        doublelink.showBeginToEnd();//1-2-3
        System.out.println("==========================");
        doublelink.showEndToBegin();//3-2-1
        System.out.println(doublelink.length());//长度为3

        doublelink.delNode(4);//没有这个节点
        doublelink.showBeginToEnd();
        System.out.println("==========");
        doublelink.updateNode(2,node5);//更换第二个节点
        doublelink.showBeginToEnd();
    }

测试结果：