Broadcasting messages

/*Server.java*/
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
import java.net.ServerSocket;
import java.util.Vector;
public class Server extends Thread{
    private Socket socket;
    private static Vector<PrintWriter> writers = new Vector<PrintWriter>();
    public Server(Socket socket) {
        this.socket = socket;
    }
    public void run() {
        try {
            BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
            out.println("SUBMITNAME");
            String name = in.readLine();
            System.out.println(name+" joined");
            writers.add(out);
            while (true) {
                String input = in.readLine();
                for (PrintWriter writer : writers)
                    writer.println("MESSAGE " + name + ": " + input);
            }
        } catch (Exception e) {System.err.println(e);}
    }
    public static void main(String[] args) throws Exception {
        ServerSocket serversocket = new ServerSocket(9001);
        System.out.println("The server is running at port 9001.");
        while (true)
            new Server(serversocket.accept()).start();
    }
}

/*Client.java*/
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.Scanner;
public class Client {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        Socket socket = new Socket("localhost", 9001);
        BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
        PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
        System.out.print("Enter your name: ");
        String name = sc.nextLine();
        while (true) {
            String line = in.readLine();
            if (line.startsWith("SUBMITNAME")) out.println(name);
            else if (line.startsWith("MESSAGE"))
                System.out.println(line.substring(8));
            if(name.startsWith("master")){
                System.out.print("Enter a message: ");
                out.println(sc.nextLine());
            }
        }
    }
}