如何用Java制作简易留言板支持点赞

public class Message {
    private String content;
    private String author;
    private int likes;
<pre class='brush:java;toolbar:false;'>public Message(String content, String author) {
    this.content = content;
    this.author = author;
    this.likes = 0;
}

public void like() {
    this.likes++;
}

public String getContent() {
    return content;
}

public String getAuthor() {
    return author;
}

public int getLikes() {
    return likes;
}

@Override
public String toString() {
    return "[" + author + "]: " + content + " (?" + likes + ")";
}

import java.util.ArrayList;
import java.util.Scanner;
<p>public class MessageBoard {
private ArrayList<Message> messages = new ArrayList<>();
private Scanner scanner = new Scanner(System.in);</p><pre class='brush:java;toolbar:false;'>public void start() {
    while (true) {
        System.out.println("\n--- 简易留言板 ---");
        System.out.println("1. 发布留言");
        System.out.println("2. 查看所有留言");
        System.out.println("3. 点赞留言");
        System.out.println("4. 退出");
        System.out.print("请选择操作：");

        int choice = scanner.nextInt();
        scanner.nextLine(); // 消费换行

        switch (choice) {
            case 1:
                postMessage();
                break;
            case 2:
                viewMessages();
                break;
            case 3:
                likeMessage();
                break;
            case 4:
                System.out.println("再见！");
                return;
            default:
                System.out.println("无效选择，请重试。");
        }
    }
}

private void postMessage() {
    System.out.print("输入你的名字：");
    String author = scanner.nextLine();
    System.out.print("输入留言内容：");
    String content = scanner.nextLine();
    messages.add(new Message(content, author));
    System.out.println("留言已发布！");
}

private void viewMessages() {
    if (messages.isEmpty()) {
        System.out.println("还没有留言哦～");
    } else {
        for (int i = 0; i < messages.size(); i++) {
            System.out.println((i + 1) + ". " + messages.get(i));
        }
    }
}

private void likeMessage() {
    viewMessages();
    if (messages.isEmpty()) return;

    System.out.print("输入要点赞的留言编号：");
    int index = scanner.nextInt() - 1;
    if (index >= 0 && index < messages.size()) {
        messages.get(index).like();
        System.out.println("点赞成功！");
    } else {
        System.out.println("编号无效！");
    }
}

public class Main {
    public static void main(String[] args) {
        new MessageBoard().start();
    }
}