Question

我正在尝试实现LinkedList，我遇到的问题是在此列表中添加元素，我已经在主类中添加了元素，并且想知道如何在列表的开头添加元素，并且在列表的末尾。当前可以打印，但是当我添加新元素时无法看到它们。我还想知道有关获取链表大小的信息。

class Node {
    int data;
    Node next;
    Node(int data){
        this.data = data;
    }

}

public class LinkedList {
    Node head;
    int size;


    public void AddBeginning(int data) {
            Node newNode = new Node(data);
            newNode.next = head;
            this.size++;        
            head = newNode;

    }

    public void addAtEnd(int data) {
        Node current = head;
        while(current.next != null) {
            current = current.next;
        }
        current.next = new Node(data);  
    } 

    public void getSize() {
        System.out.println(size);
    }

    public void printList(Node head) {
        Node current = head;
        while (current !=null) {
        System.out.print(current.data + "-->");
        current = current.next;
        }       
        System.out.print(current);
    }

}


public class Tester {


    public static void main(String[] args) {

        LinkedList ll = new LinkedList();


        Node head = new Node(25);

        Node second = new Node(22);

        Node third = new Node(7);

        head.next = second;
        second.next = third;

        ll.AddBeginning(20);

        ll.printList(head);




    }

    }

我想在开头添加20，在结尾添加另一个整数。

Answer 1

您正在将节点20 this.rankingObs = this.rankingService.getAll().pipe( mergeMap(ranking => { // an array of all observables which will return the merged rank and member data const ranksWithMembers = ranking.map(rank=>{ return this.memberService.get(rank.key).pipe( map(member=>{ return { ...rank, firstName: member.firstName, lastName: member.lastName, keyName: member.key, } }) ) }) // does not emit until all observables in array emit. Emits all results. return forkJoin(ranksWithMembers) }), ).subscribe(...)添加到ll.AddBeginning(20);，并尝试使用LinkedList.head打印列表

解决方案：第1步：要么初始化LinkedList.head，要么

Tester.head (declared in main method)

第2步：无需将head变量传递给printList（）函数。它打印出LinkedList.head元素

     - Using constructor or
             LinkedList ll = new LinkedList(head);

             public LinkedList(Node head) {
                 this.head = head;
             }

     - Assign head to LinkedList object i.e., ll
              ll.head = head; // Need to initialize Linked List with Head

代码：

测试器主要方法

         ll.printList(); //Here you passing Tester.head not required

LinkedList.PrintList方法

    ll.head = head; // Need to initialize Linked List with Head

    ll.AddBeginning(20); //Here actually adding node to linkedList head

    ll.printList(); //Here you passing Tester.head not required

链表在某些点添加元素

1 个答案: