import java.util.ArrayList;import java.util.Date;import java.util.Scanner;class Message {private String content;private Date timestamp;public Message(String content) {this.content = content;this.timestamp = new Date();}public String getContent() {return content;}public Date getTimestamp() {return timestamp;}}public class MessageApp {private ArrayList messages;public MessageApp() {messages = new ArrayList<>();}public void receiveMessage(String content) {if (messages.size() >= 20) {messages.remove(0);}Message message = new Message(content);messages.add(message);System.out.println("收到新消息：" + content);}public void displayMessages() {if (messages.size() == 0) {System.out.println("短消息列表为空");} else {System.out.println("短消息列表：");for (int i = 0; i < messages.size(); i++) {System.out.println((i + 1) + ". " + messages.get(i).getContent());}}}public void readMessage(int index) {if (index < 1 || index > messages.size()) {System.out.println("无效的消息索引");} else {Message message = messages.get(index - 1);System.out.println("消息内容：" + message.getContent());System.out.println("接收时间：" + message.getTimestamp());}}public void deleteMessage(int index) {if (index < 1 || index > messages.size()) {System.out.println("无效的消息索引");} else {messages.remove(index - 1);System.out.println("删除成功");}}public void clearMessages() {messages.clear();System.out.println("所有短消息已清除");}public static void main(String[] args) {MessageApp messageApp = new MessageApp();Scanner scanner = new Scanner(System.in);int choice;do {System.out.println("请选择操作：");System.out.println("1. 接收新消息");System.out.println("2. 显示短消息列表");System.out.println("3. 阅读短消息");System.out.println("4. 删除短消息");System.out.println("5. 清除所有短消息");System.out.println("0. 退出");choice = scanner.nextInt();switch (choice) {case 1:System.out.println("请输入新消息内容：");scanner.nextLine(); // Consume the new line characterString content = scanner.nextLine();messageApp.receiveMessage(content);break;case 2:messageApp.displayMessages();break;case 3:System.out.println("请输入要阅读的消息索引：");int readIndex = scanner.nextInt();messageApp.readMessage(readIndex);break;case 4:System.out.println("请输入要删除的消息索引：");int deleteIndex = scanner.nextInt();messageApp.deleteMessage(deleteIndex);break;case 5:messageApp.clearMessages();break;case 0:System.out.println("程序已退出");break;default:System.out.println("无效的选择");break;}}System.out.println(); } while (choice != 0);}