sending string from one client to another client by using server

Right now I have two client classes I opened my server socket I connected them but the problem is I wanna send a string from one client to another client. Also my clients connect from my local host. But I wanna give them a identical ıp how can I make it. I have to send string from one client to another client by using my server.

public class MainServer {
public static void main(String[] args) throws IOException {
    Socket s = null;
    ServerSocket ss2 = null;
    System.out.println("Server listening...");
    ss2 = new ServerSocket(5151);

    while (true) {
        try {
            s = ss2.accept();
            System.out.println("Connection started");
            ServerThread st = new ServerThread(s);
            st.start();
        } catch (Exception e) {
            System.out.println("Error Occurred");
        }
    }
}

}

class ServerThread extends Thread {
String line = null;
DataInputStream is = null;
DataInputStream br = null;
PrintWriter os = null;
Socket sl = null;

public ServerThread(Socket s) {
    sl = s;
}

public void run() {
    try {
        is = new DataInputStream(sl.getInputStream());
        os = new PrintWriter(sl.getOutputStream());
        line = is.readLine();
        while (line.compareTo("Quit") != 0) {
            os.println(line);
            os.flush();
            System.out.println("Response of Client:" + line);
            line = is.readLine();
        }
        is.close();
        os.close();
        sl.close();
    } catch (Exception e) {
    }
}

}

and here is my client

public class Client2 {
/**
 * @param args
 * @throws IOException
 */
public static void main(String[] args) throws IOException {
    Socket sl = null;
    String line = null;
    DataInputStream br = null;
    DataInputStream is = null;
    PrintWriter os = null;

    try {
        sl = new Socket("127.0.0.1", 5151);
        br = new DataInputStream(System.in);
        is = new DataInputStream(sl.getInputStream());
        os = new PrintWriter(sl.getOutputStream());
    } catch (IOException e) {
        System.out.println("IO Exception");
    }
    System.out.println("Enter data to echo server");
    String response = null;
    try {
        line = br.readLine();
        while (line.compareTo("Quit") != 0) {
            os.println(line);
            os.flush();
            response = is.readLine();
            System.out.println("Server response:" + response);
            line = br.readLine();
        }
        is.close();
        os.close();
        br.close();
        sl.close();
        System.out.println("Connection closed");

    } catch (Exception e) {
        System.out.println("Socket error");
    }
}

}