java实现简单单链表

package com.example.demo.linkedlist;
 
/**
 * 结点
 * Created by xinan on 2021/02/23
 */
public class Node {
 
  public Integer value;
 
  public Node next;
 
  public Node(Integer value) {
    this.value = value;
  }
 
  public Node(Integer value, Node next) {
    this.value = value;
    this.next = next;
  }
 
  public Integer getValue() {
    return value;
  }
 
  public void setValue(Integer value) {
    this.value = value;
  }
 
  public Node getNext() {
    return next;
  }
 
  public void setNext(Node next) {
    this.next = next;
  }
  
}

package com.example.demo.linkedlist;
 
 
/**
 * 单链表
 * Created by xinan on 2021/2/23
 */
public class SingleLinkedList {
 
  public Node head;
 
  /**
   * 从头部添加
   * @param data 待添加数据
   */
  public void addHead(Integer data) {
    Node node = new Node(data);
    node.next = head;
    head = node;
  }
 
  /**
   * 从尾部添加
   * @param data 待添加数据
   */
  public void addLast(Integer data) {
    Node node = new Node(data);
    if (head == null) {
      head = node;
      return;
    }
    Node temp = head;
    while (temp.next != null) {
      temp = temp.next;
    }
    temp.next = node;
  }
 
  /**
   * 获取链表的长度
   * @return 链表长度
   */
  public Integer length() {
    int length = 0;
    Node temp = head;
    while (temp != null) {
      temp = temp.next;
      length ++;
    }
    return length;
  }
 
  /**
   * 从指定下标处添加
   * @param index 指定下标
   * @param data 待添加的数据
   */
  public void addByIndex(int index, Integer data) {
    if (index < 0 || index > length()) {
      System.out.println("插入下标不合规，请检查!");
      return;
    }
    if (index == 0) {
      addHead(data);
      return;
    }
    Node node = new Node(data);
    Node temp = head;
    for (int i = 1; i < index; i++) {
      temp = temp.next;
    }
    node.next = temp.next;
    temp.next = node;
  }
 
  /**
   * 指定下标删除
   * @param index 指定下标
   */
  public void deleteByIndex(int index) {
    if (index < 0 || index > length()) {
      System.out.println("删除下标不合规，请检查!");
      return;
    }
    if (index == 0) {
      head = head.next;
      return;
    }
    Node temp = head;
    for (int i = 1; i < index; i++) {
      temp = temp.next;
    }
    temp.next = temp.next.next;
  }
 
  /**
   * 通过下标获取结点
   * @param index 下标
   * @return 结点
   */
  public Node getByIndex(Integer index) {
    if (index < 0 || index > length() - 1) {
      System.out.println("不存在此下标结点");
    }
    Node temp = head;
    int i = 0;
    while (temp != null) {
      if (i == index) {
        return temp;
      }
      i ++;
      temp = temp.next;
    }
    return null;
  }
 
  /**
   * 打印链表值
   */
  public void printLink() {
    Node temp = head;
    while (temp != null) {
      System.out.println(temp.value);
      temp = temp.next;
    }
  }
 
  /**
   * 打印某个节点之后的所有值
   * @param node
   */
  public static void printAfterNode(Node node) {
    while (node != null) {
      System.out.println(node.value);
      node = node.next;
    }
  }
 
  /**
   * 清除单链表
   */
  public void clearLink() {
    head = null;
  }
 
  /**
   * 单链表反转
   * @param head 头节点
   */
  public Node reverseLink(Node head) {
    Node prev = null;
    Node curr = head;
    while (curr != null) {
      Node nextTemp = curr.next;
      curr.next = prev;
      prev = curr;
      curr = nextTemp;
    }
    return prev;
  }
 
  /**
   * 测试
   * @param args
   */
  public static void main(String[] args) {
    SingleLinkedList linkNode = new SingleLinkedList();
    linkNode.addHead(2);
    linkNode.addHead(3);
    linkNode.addHead(5);
    linkNode.addLast(9);
    linkNode.addLast(7);
    System.out.println("打印单链表: ");
    linkNode.printLink();
    Node byIndex1 = linkNode.getByIndex(0);
    System.out.println("获取下标为1的结点值: " + byIndex1.value);
    linkNode.addByIndex(2, 8);
    System.out.println("下标2添加后打印单链表: ");
    linkNode.printLink();
    linkNode.addByIndex(0, 11);
    System.out.println("下标0添加后打印单链表: ");
    linkNode.printLink();
    linkNode.deleteByIndex(0);
    System.out.println("下标0删除后打印单链表: ");
    linkNode.printLink();
    Node node = linkNode.reverseLink(linkNode.head);
    System.out.println("反转后打印单链表: ");
    printAfterNode(node);
  }
 
}