双向链表实现思路

双向链表

实现思路

遍历

和单向链表的遍历相同，需要一个辅助节点来保存当前正在遍历的节点

添加

双向链表多出了一个front，所以在添加时，要让新增节点的front指向链表尾节点

修改

和单向链表的修改相同

删除

使用temp来保存要删除的节点
temp.front.next指向temp.next
temp.next指向temp.front

代码

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

package com.wyh.linkedlist;
 
public class DoubleLinkedListDemo {
    public static void main(String[] args) {
        StudentLinked studentLinked = new StudentLinked();
        studentLinked.addNode(new Node(1,"张三"));
        studentLinked.addNode(new Node(2,"李四"));
        studentLinked.addNode(new Node(3,"王五"));
        studentLinked.addNode(new Node(4,"二蛋"));
 
        studentLinked.updateNode(new Node(4,"狗蛋儿"));
        studentLinked.delete(4);
        studentLinked.list();
    }
}
 
class StudentLinked{
    //定义头节点
    private Node head = new Node(0,"");
 
    //遍历双向链表
    public void list(){
        if (head.next == null){
            System.out.println("链表为空");
            return;
        }
        Node temp = head.next;
        while (true){
            if (temp == null){
                break;
            }
            System.out.println(temp);
            temp = temp.next;
        }
    }
 
    //添加节点
    public void addNode(Node newNode){
        Node temp = head;
        while(temp.next!=null){
            temp = temp.next;
        }
        temp.next = newNode;
        newNode.front = temp;
    }
 
    //删除节点
    public void delete(int no){
        if (head.next == null){
            System.out.println("链表为空");
            return;
        }
        Node temp = head.next;
        boolean flag = true;
        while (temp!=null){
            if (temp.no == no){
                if (temp.next!=null){
                    temp.next.front = temp.front;
                }
                temp.front.next = temp.next;
                flag =false;
            }
            temp = temp.next;
        }
        if (flag){
            System.out.println("未找到节点");
        }
    }
 
    //更改节点的信息
    public void updateNode(Node newNode) {
        if (head.next == null){
            System.out.println("队列为空,无法更改");
            return;
        }
        Node temp = head.next;
        boolean flag = false;
        while (true){
            if (temp == null){
                break;
            }
            if (temp.no == newNode.no){
                flag = true;
                break;
            }
            temp = temp.next;
        }
        if (flag){
            temp.name = newNode.name;
        }else {
            System.out.printf("没有找到编号为%d的节点,无法修改\n",newNode.no);
        }
    }
 
 
}
 
//定义节点的类
class Node{
    public int no;
    public String name;
    public Node next;//指向下一个节点
    public Node front;//指向上一个节点
 
    public Node(int no, String name) {
        this.no = no;
        this.name = name;
    }
 
    @Override
    public String toString() {
        return "Node{" +
                "no=" + no +
                ", name='" + name + '\'' +
                '}';
    }
}