Multi threading in java socket program

Question

I want to implement multi-threading in my Java socket program. So far I've tried a single connection and it works, but due to being a single connection the process is slow. How should I proceed in order to make the process faster with multi-threading?

import java.io.BufferedInputStream;
import java.io.BufferedWriter;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.Socket;

public class MRPosting {
    public static String MRPost(String strRequestMessage, String strIP,
            int intPort) throws Exception {
        String strResponseMessage = "";
        try{
        Socket socket = null;
        socket = new Socket(strIP, intPort);
        BufferedInputStream bin = new BufferedInputStream(
                socket.getInputStream());

        PrintWriter pw1 = new PrintWriter(new BufferedWriter(
                new OutputStreamWriter(socket.getOutputStream())), true);
        pw1.println(strRequestMessage);
        pw1.flush();

        strResponseMessage = readInputStream(bin);
        socket.close();
        socket = null;
        }catch(Exception e){
            strResponseMessage = "ERROR:MRPORT_JAVA:"+e.toString();
            return strResponseMessage;
        }
        return strResponseMessage;  

    }

    public static String readInputStream(BufferedInputStream in)
        throws Exception {
        String read_msg = "";

        int i = in.read();
        if (i == -1) {
            return "-1";
        }
        read_msg = read_msg + (char) i;
        int available = in.available();
        if (available > 0) {
            byte[] Data = new byte[available];
            in.read(Data);
            read_msg = read_msg + new String(Data);
        }
        return read_msg;
    }

}

Answer 1

Multi-threading != increase in speed.

You should read (Google) a lot more about client/server socket programming because yours is not even close to a functioning program. You need a ServerSocket listening on the server and accepting connections from clients, for each connection you will need to open a Socket connection and exchange information through the IO streams.

Answer 2

You won't make this process any faster with multi-threading, unless there are multiple connections, but if there are, just call this stuff from multiple threads with multiple sockets, streams, etc. There's nothing inherently non-thread safe here, as you aren't using any static or instance variables.

NB Get rid of the available() test. It doesn't do what you think. See the Javadoc.