package test;import java.util.*;public class Main {    public static void main(String[] args) {        List<Message> received = List.of(                new Message(1, "Hello!"),                new Message(2, "发工资了吗？"),                new Message(2, "发工资了吗？"),                new Message(3, "去哪吃饭？"),                new Message(3, "去哪吃饭？"),                new Message(4, "Bye")        );        List<Message> displayMessages = process(received);        for (Message message : displayMessages) {            System.out.println(message.text);        }    }    static List<Message> process(List<Message> received) {        Set<Message> msgSet = new HashSet<>(received);        List<Message> msgList = new ArrayList<>(msgSet);        return msgList;    }}    class Message {        public final int sequence;        public final String text;        public Message(int sequence, String text) {            this.sequence = sequence;            this.text = text;        }        public boolean equals(Object o){            if (o instanceof Message){                Message msg = (Message) o;                return this.sequence == msg.sequence && Objects.equals(this.text, msg.text);            }            else{                return false;            }        }        public int hashCode(){            return Objects.hash(sequence, text);        }}