Concurrent TCP Client-Server

//Server.java
import java.net.ServerSocket;
import java.net.Socket;
import java.io.*;
class Server implements Runnable{
    static ServerSocket ss;
    Socket s;
    public void run(){
        try{
            BufferedReader fromClient = new BufferedReader(new InputStreamReader(s.getInputStream()));
            PrintStream toClient = new PrintStream(s.getOutputStream());

            String ip = "";
            while((ip=fromClient.readLine())!=null){
                System.out.println(ip);
                toClient.println(ip.toUpperCase());
                if(ip.equals("bye")) break;
            }
        } catch(Exception e){e.printStackTrace();}
    }
    Server(Socket s){
        this.s = s;
    }
    public static void main(String[] args) throws IOException{
        ss = new ServerSocket(9812);
        while(true){
            new Thread(new Server(ss.accept())).start();
        }
    }
}

//Client.java
import java.net.Socket;
import java.io.*;
class Client{
    public static void main(String[] args){
        try{
            Socket s = new Socket("localhost", 9812);
            BufferedReader fromServer = new BufferedReader(new InputStreamReader(s.getInputStream()));
            PrintStream toServer = new PrintStream(s.getOutputStream());

            BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
            System.out.println("Enter a string to capitalize.");
            String ip;
            while(!(ip=br.readLine()).equals("bye")){
                toServer.println(ip);
                System.out.println(fromServer.readLine());
            }
            s.close();
        } catch(Exception e){e.printStackTrace();}
    }
}