对于一个学校项目，我不得不用java和多个用户聊天。我做到了，但我不认为这是完美的。将来我想添加一个gui，但在这样做之前我想纠正它。所以我的问题是如何改进它？我能做得更好吗？。这是我的密码。在客户端，我使用主线程等待用户输入，另一个线程侦听服务器，等待来自另一个客户端的消息。在服务器端，我使用主线程接受来自客户端的新连接请求，并使用管理n个客户端的n个线程。请帮帮我。
客户端：

import java.net.*;
import java.io.*;
class listener implements Runnable{
    private Socket connection;
    private static boolean running;
    listener(Socket connection){
        this.connection=connection;
        running=true;
    }
    public void run(){
        InputStreamReader in;
        BufferedReader sIN;
        String msgToRecv;
        try{
            in=new InputStreamReader(connection.getInputStream());
            sIN=new BufferedReader(in);
        }
        catch(IOException e){
            System.out.println(e);
            return;
        }
        while(running){
            try{
                msgToRecv=sIN.readLine();
            }
            catch(IOException e){
                System.out.println("Connection closed: "+e);
                return;
            }
            System.out.println(msgToRecv);
        }
        return;
    }
    public static void stopListening(){
        running=false;
        return;
    }
}
class Client
{
    public static void main(String[] args)
    {
        String ipAddServer="127.0.0.1";
        int port=8080;
        Socket connection=null;
        String msgToSend;
        String username;
        InputStreamReader input=new InputStreamReader(System.in);
        BufferedReader tastiera=new BufferedReader(input);
        OutputStream out;
        PrintWriter sOUT;
        System.out.println("Enter a username");
        try{
            connection=new Socket(ipAddServer, port);
            out=connection.getOutputStream();
            sOUT=new PrintWriter(out);
            username=tastiera.readLine();
        }
        catch(IOException e){
            System.out.println(e);
            return;
        }
        System.out.println("User: "+username);
        System.out.println("Chat Joined");
        Thread t=new Thread(new listener(connection));
        t.start();
        do{
            try{
                msgToSend=tastiera.readLine();
            }
            catch(IOException e){
                System.out.println(e);
                return;
            }
            sOUT.println(username+": "+msgToSend);
            sOUT.flush();
        }while(!msgToSend.equals("EXIT"));
        listener.stopListening();
        try
        {
            connection.close();
        }
        catch(IOException e)
        {
            System.out.println(e);
        }
        return;
    }
}

服务器端：

import java.net.*;
import java.io.*;
import java.util.ArrayList;
class clientHandler implements Runnable{
    private ServerSocket sSocket;
    private Socket connection;
    private ArrayList<Socket> sockets;
    public clientHandler(ServerSocket sSocket, Socket connection, ArrayList<Socket> sockets) {
        this.sSocket=sSocket;
        this.connection=connection;
        this.sockets=sockets;
    }
    public void run(){
        InputStreamReader in, input;
        BufferedReader sIN, tastiera;
        OutputStream out;
        PrintWriter sOUT;
        String msgToRecv;
        try{
            out=connection.getOutputStream();
            sOUT=new PrintWriter(out);
            in=new InputStreamReader(connection.getInputStream());
            sIN=new BufferedReader(in);
        }
        catch(Exception e){
            System.out.println(e);
            return;
        }
        sockets.add(connection);
        do{
            try{
                msgToRecv=sIN.readLine();
            }
            catch(IOException e){
                System.out.println(e);
                return;
            }
            for(int i=0;i<sockets.size();++i){
                Socket temp=sockets.get(i);
                if(!connection.equals(temp)&&!msgToRecv.equals("null")){
                    OutputStream tmpOut;
                    PrintWriter tmpSOUT;
                    try{
                        tmpOut=temp.getOutputStream();
                        tmpSOUT=new PrintWriter(tmpOut);
                    }
                    catch(IOException e){
                        System.out.println(e);
                        return;
                    }
                    tmpSOUT.println(msgToRecv);
                    tmpSOUT.flush();
                }
            }
        }while(msgToRecv!=null);
        sockets.remove(sOUT);
        return;
    }
}
class Server
{
    public static void main(String[] args)
    {
        int port=8080;
        ServerSocket sSocket;
        ArrayList<Socket> sockets=new ArrayList<Socket>();
        Thread t;
        try{
            sSocket=new ServerSocket(port);
        }
        catch(IOException e){
            System.out.println(e);
            return;
        }
        while(true){
            try{
                t=new Thread(new clientHandler(sSocket, sSocket.accept(), sockets));
            }
            catch(IOException e){
                System.out.println(e);
                return;
            }
            t.start();
        }
    }
}