单链表如何用java语言实现

Question

如题，要完整的代码，包含最基本的链表是否为空，链表长度，在头或尾部添加元素，在头部移除元素(尾部不要求)

Answer 1

/**

• 单链表实现

• @author caasi

• @since 2021-07-28 16:58:20

• /
  public class SinglyLinkedList implements Cloneable{
  /**

  • 需要有的最基本的方法
  • size() 返回链表的长度
  • isEmpty() 判断链表是否为空
  • addFirst() 在链表头部添加元素
  • addLast() 在链表尾部添加元素
  • first() 返回链表的第一个元素，如果链表为空，则返回null
  • last() 返回链表的最后一个元素，如果链表为空，则返回null
  • removeFirst() 删除并返回链表的第一个元素，如果链表为空，则返回null
  • /

  /**

  • 节点内部类

  • @param

  • /
    private class Node{
    private E element;
    private Node next;
    public Node(E e, Node n){

      element = e;
      next = n;
    

    }

    public E getElement(){

      return element;
    

    }

    public Node getNext() {

      return next;
    

    }

    public void setNext(Node next) {

      this.next = next;
    

    }
    }

  //头节点
  private Node head;
  //尾节点
  private Node tail;
  //链表长度
  private int size;

  public int size(){

    return size;
  

  }

  public boolean isEmpty(){

    return size == 0;
  

  }

  public E first(){

    if(isEmpty()) return null;
    return head.getElement();
  

  }

  public E last(){

    if(isEmpty()) return null;
    return tail.getElement();
  

  }

  public E removeFirst(){

    if(isEmpty()) return null;
    E e = head.getElement();
    head = head.getNext();
    size -- ;
    if(isEmpty()) tail = null;
    return e;
  

  }

  public void addFirst(E e){

    head = new Node<>(e, head);
    if(isEmpty()) tail = head;
    size ++;
  

  }

  public void addLast(E e){

    Node<E> newNode = new Node<>(e, null);
    if(isEmpty()){
        head = newNode;
    } else {
        tail.setNext(newNode);
    }
    size ++;
    tail = newNode;
  

  }

  public void add(E e){

    addLast(e);
  

  }

  public void print(){

    if(isEmpty()) return;
    Node<E> node = head;
    while(node != null){
        System.out.println(node.getElement());
        node = node.getNext();
    }
  

  }

  @Override
  public boolean equals(Object obj) {

    if (obj == null) return false;
    if(getClass() != obj.getClass()) return false;
    SinglyLinkedList o = (SinglyLinkedList) obj;
    if(size != o.size) return false;
    Node walkA = head;
    Node walkB = o.head;
    while (walkA != null){
        if(!walkA.getElement().equals(walkB.getElement())){
            return false;
        }
        walkA = walkA.getNext();
        walkB = walkB.getNext();
    }
    return true;
  

  }

  @Override
  protected Object clone() throws CloneNotSupportedException {

    SinglyLinkedList other = (SinglyLinkedList) super.clone();
    if (size > 0){
        other.head = new Node<E>(head.getElement(), null);
        Node<E> walk = head.getNext();
        Node<E> otherTail = other.head;
        while (walk != null){
            Node<E> newest = new Node<>(walk.getElement(), null);
            otherTail.setNext(newest);
            otherTail = newest;
            walk = walk.getNext();
        }
    }
    return other;
  

  }
  }