This Server accepts requests and sends information

Server.java

import java.io.*;
import java.net.*;
import java.util.Scanner;

public class Server {
    private ServerSocket serverSocket = null;
    private Socket socket = null;
    private ServerThread serverThread;

    Server(int port) {
        try {
            serverSocket = new ServerSocket();
            InetSocketAddress address = new InetSocketAddress(port);
            serverSocket.bind(address);
        } catch (IOException e) {
            e.printStackTrace();
        }

    }

    public static void main(String[] args) {
        Server server = new Server(1234);
        server.startServer();
    }

    public void startServer() {
        serverThread = new ServerThread(serverSocket);
        serverThread.start();
    }

    public void stoprServer() {
        try {
            serverSocket.close();
            Thread.interrupted();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    class ServerThread extends Thread {
        private ServerSocket serverSocket;
        private boolean running = true;

        ServerThread(ServerSocket serverSocket) {
            this.serverSocket = serverSocket;
        }

        public void stopRunning() {
            running = false;
        }

        public void run() {
            while (running) {
                try {
                    socket = serverSocket.accept();
                    SocketThread socketThread = new SocketThread(socket);
                    socketThread.start();
                    socketThread.setReadListener(new ReadListener() {
                        @Override
                        public String read(String string) {
                            System.out.println(string);
                            return "information about " + string;
                        }
                    });
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    class SocketThread extends Thread {
        private BufferedReader br;
        private ReadListener readListener;
        private Writer writer;
        private Socket socket;

        SocketThread(Socket socket) {
            this.socket = socket;
        }

        void setReadListener(ReadListener readListener) {
            this.readListener = readListener;
        }

        public void run() {
            try {
                InputStream is = socket.getInputStream();
                OutputStream os = socket.getOutputStream();
                writer = new OutputStreamWriter(os, "ASCII");
                br = new BufferedReader(new InputStreamReader(is));
                String string = "";
                if ((string = br.readLine()) != null) {
                    writer.write(readListener.read(string));
                    writer.flush();
                    writer.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    interface ReadListener {
        public String read(String string);
    }
}