Newbie Sockets Question

Question

Hi - I'm new to Java and have been trying to create a class to encapsulate socket communication. It doesn't work and I don't understand why?
As I figure I've created and instance of SocketCommunication, called SetUpSocket (which works) and then called SocketSend to work on the mySocket instance. But my server never receives anything...
What am I doing wrong?
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public class SocketTester {
    public SocketTester() {
    public static void main(String[] args) {
        SocketCommunication mySocket = new SocketCommunication("localhost", 4000, 4001);
        mySocket .SetUpSocket();
        String strReceived = mySocket .doSend("HELLO");
        System.out.print(strReceived);
=================================================================
import java.util.*;
import java.io.*;
import java.net.*;
public class SocketCommunication {
    private Socket inClient;
    private Socket outClient;
    private BufferedReader socketReader;
    private PrintWriter socketWriter;
    private String host;
    private int outPort;
    private int inPort;
    public SocketCommunication(String host, int outPort, int inPort) {
        this.host = host;
        this.outPort = outPort;
        this.inPort = inPort;
    public boolean SetUpSocket(){
        try {
            outClient = new Socket(host, outPort);
            outClient.setKeepAlive(true);
            socketWriter = new PrintWriter(outClient.getOutputStream());
            inClient = new Socket(host, inPort);
            inClient.setKeepAlive(true);
            socketReader = new BufferedReader(new InputStreamReader(inClient.getInputStream()));
        } catch (UnknownHostException e) {
            System.out.println("Error setting up socket connection: unknown host " + host );
            return false;
        } catch (IOException e) {
            System.out.println("Error setting up socket connection: " + e);
            return false;
        return true;
    public String doSend(String sendString) {
        String receiveString = null;
        try{
            socketWriter.print(sendString);
            socketWriter.flush();
            receiveString = getData(socketReader);
            if (null == receiveString) {
                System.out.println("no response");
        } catch (IOException e) {
            System.out.println("Error communicating: " + e);
        //receiveString = "test";
        return receiveString;
    public String getData(BufferedReader in) throws IOException {
        int iIncomingCharacter;
        StringBuffer sbMsgBuilder = new StringBuffer();
        String sMsg = null;
        while ( true ) {
            // Read character
            iIncomingCharacter = in.read();
            if ((iIncomingCharacter) == -1) {
                sMsg = "-1";
                break;
            // Append character to buffer
            sbMsgBuilder.append((char) iIncomingCharacter);
            // Test to see if "$END$\n" has been received
            if ((sbMsgBuilder.length()>6) && (sbMsgBuilder.substring(sbMsgBuilder.length()-6).equals("$END$\n"))) {
                // Convert buffer to string
                sMsg = sbMsgBuilder.toString();
                // Reset the buffer for next message
                sbMsgBuilder.delete(0,sbMsgBuilder.length());
                break;
        return sMsg;
=================================================================

Answer 1

>>>
Connecting of course requires something toconnect
"to".Indeed.
So are you saying ServerSocket is required?
I don't use ServerSocket when I connect to a
database. But there is still something to connect
"to".Yes, I know.
I'm talking specifically about the OP's case of Java talking to Java.
But in java you would need to use a server of some
sort although (guessing) for nio you need
ServerSocketChannel rather than ServerSocket. Still
a server though.I suspected as much. I just didn't know for certain that Socket didn't have a method to allow it to fullfil ServerSocket's role in some capacity. I wouldn't expect it, but I didn't know for sure and couldn't be bothered to check. I didn't look that closely at the OP's code and didn't want to send him off with bad advice if he was just doing something that was legit but outside my own knowledge.