BufferedReader readLine method freezes and blocks the program

I am trying to learn sockets using Java, and I successfully sent data to a ServerSocket running on my own machine. When I try to read from this socket using readline (so that I can simply respond to my sent message), my program freezes and will not return.

Here is the code:

public static void main(String[] args) throws UnknownHostException, IOException {

    TCPClient cli = new TCPClient("127.0.0.1", "15000");
    try {
        cli.ostream.writeUTF("Teste");
        String echo = cli.istream.readLine(); //it hangs in this line
        System.out.println(echo);
    }

TCPClient is the class I defined, so I can test my program on a simpler interface before using swing in my homework. here is the code:

public class TCPClient {

public DataOutputStream ostream = null;
public BufferedReader istream = null;

public TCPClient(String host, String port) throws UnknownHostException {
    InetAddress ip = InetAddress.getByName(host);

    try {
        Socket socket = new Socket(host, Integer.parseInt(port));

        ostream = new DataOutputStream(socket.getOutputStream());
        istream = new BufferedReader(new InputStreamReader(socket.getInputStream()));


    } catch (IOException ex) {
        Logger.getLogger(TCPClient.class.getName()).log(Level.SEVERE, null, ex);
    }

}

My server is pretty simple. After establishing a connection, he enters this loop and remains here until I close the client (due to an infinite loop). Subsequently, the exception handling returns it to the point before the start of the connection.

            while(true){
                String msg = istream.readLine();
                System.out.println("Arrived on server: " + msg); //just works on debug
                ostream.writeUTF("ACK: " + msg);
                ostream.flush();
            }

I don’t see what I am missing.

PS: wierd - , , , (, ), , . - concurrency, ?