单链表(一)---- 增删查改操作
直接上代码:
import java.util.Scanner; public class LinkedList { class Node { int val; Node next = null; public Node(int val, Node next) { this.val = val; this.next = next; } public Node(int val) { this(val, null); } } private Node headNode; //头指针 private int size; //元素总数 public LinkedList() { this.headNode = null; this.size = 0; } //获取链表个数 public int getSize() { return this.size; } //向链表头部添加元素 public void addNodeOnFirst(int data) { Node newNode = new Node(data); newNode.next = this.headNode; this.headNode = newNode; this.size++; } //向链表尾部添加元素 public void addNodeOnLast(int data) { this.add(data, this.size); } //向指定位置添加元素 public void add(int data, int index) { if (index < 0 || index > this.size) { // System.out.println("下标越界异常"); throw new IllegalArgumentException("index is out error"); } if (index == 0) { this.addNodeOnFirst(data); return; } Node preNode = this.headNode; for (int i = 0; i < index - 1; i++) { preNode = preNode.next; } Node newNode = new Node(data); newNode.next = preNode.next; preNode.next = newNode; this.size++; } //删除链表指定位置的元素 public void remove(int index) { if (index <= 0 || index > this.size) { System.out.println("这个位置没任何元素"); return; } if (index == 1) { headNode = headNode.next; this.size--; return; } Node temp = headNode; for (int i = 1; i < index - 1; i++) { temp = temp.next; } temp.next = temp.next.next; this.size--; } //删除最后一个元素 public void removeLast() { this.remove(this.size); } //删除链表第一个元素 public void removeFirst() { this.remove(1); } //修改指定位置的元素值 public void update(int index, int data) { if (index <= 0 || index > this.size) { System.out.println("这个位置没任何元素"); return; } Node temp = headNode; for (int i = 1; i < index - 1; i++) { temp = temp.next; } temp.next.val = data; } //重写toString方法 @Override public String toString() { StringBuilder sb = new StringBuilder(); Node cur = this.headNode; while (cur != null) { sb.append(cur.val + "->"); cur = cur.next; } sb.append("NULL"); return sb.toString(); } public static void main(String[] args) { LinkedList linked = new LinkedList(); while (true) { System.out.println(linked); System.out.println("请选择菜单:"); System.out.println("1:添加 2:删除最后一个 3:删除指定位置 4:修改指定位置的值"); Scanner scanner = new Scanner(System.in); String str = scanner.nextLine(); int in = Integer.parseInt(str); if ("00".equals(str)) { System.out.println("退出!"); break; } switch (in) { case 1: { System.out.print("请输入添加的元素:"); String s1 = scanner.nextLine(); linked.addNodeOnLast(Integer.parseInt(s1)); System.out.println("添加成功"); break; } case 2: { System.out.println("已删除"); break; } case 3: { System.out.print("删除第几个元素:"); String s1 = scanner.nextLine(); linked.remove(Integer.parseInt(s1)); System.out.println("删除成功"); break; } case 4: { System.out.print("要第几个元素:"); String s1 = scanner.nextLine(); System.out.print("新的值为:"); String s2 = scanner.nextLine(); linked.update(Integer.parseInt(s1),Integer.parseInt(s2)); System.out.println("修改"); } default: { System.out.println("输入的不对哦!"); break; } } } } }
测试结果: