Simple Java IRC Client

I am trying to write an IRC client that is very simple, with the hopes of later expanding it.

At this point I have two classes written in java that are supposed to work together and were copied from the Oracle tutorial. What I am trying to do is have the EchoClient connect to a host on a certain port so that the host running EchoServer can print out what the client types. I am trying to do exactly what the tutorial says that it does, but I am getting an error after copying and pasting the code.

EchoClient.java:

import java.io.*;
import java.net.*;

public class EchoClient {
    public static void main(String[] args) throws IOException {
    if (args.length != 2) {
        System.err.println(
            "Usage: java EchoClient <host name> <port number>");
        System.exit(1);
    }

    String hostName = args[0];
    int portNumber = Integer.parseInt(args[1]);

    try (
        Socket echoSocket = new Socket(hostName, portNumber);
        PrintWriter out =
            new PrintWriter(echoSocket.getOutputStream(), true);
        BufferedReader in =
            new BufferedReader(
                new InputStreamReader(echoSocket.getInputStream()));
        BufferedReader stdIn =
            new BufferedReader(
                new InputStreamReader(System.in))
    ) {
        String userInput;
        while ((userInput = stdIn.readLine()) != null) {
            out.println(userInput);
            System.out.println("echo: " + in.readLine());
        }
    } catch (UnknownHostException e) {
        System.err.println("Don't know about host " + hostName);
        System.exit(1);
    } catch (IOException e) {
        System.err.println("Couldn't get I/O for the connection to " +
            hostName);
        System.exit(1);
    }
}

}

EchoServer.java:

import java.net.*;
import java.io.*;

public class EchoServer {
  public static void main(String[] args) throws IOException {

    if (args.length != 1) {
        System.err.println("Usage: java EchoServer <port number>");
        System.exit(1);
    }

    int portNumber = Integer.parseInt(args[0]);

    try (
        ServerSocket serverSocket =
            new ServerSocket(Integer.parseInt(args[0]));
        Socket clientSocket = serverSocket.accept();
        PrintWriter out =
            new PrintWriter(clientSocket.getOutputStream(), true);
        BufferedReader in = new BufferedReader(
            new InputStreamReader(clientSocket.getInputStream()));
    ) {
        String inputLine;
        while ((inputLine = in.readLine()) != null) {
            out.println(inputLine);
        }
    } catch (IOException e) {
        System.out.println("Exception caught when trying to listen on port "
            + portNumber + " or listening for a connection");
        System.out.println(e.getMessage());
    }
}

}

When I try to run the compiled EchoServer from my terminal with java EchoServer 2000 I get the error, Error: Could not find or load main class EchoClient and I get the same error from java EchoServer 2000

Solution

The Echo server example shows you how to do this. First set up an output stream of some sort, using the socket that the client creates:

Socket echoSocket = new Socket(hostName, portNumber);
PrintWriter out =
    new PrintWriter(echoSocket.getOutputStream(), true);

Then when you have a message to send, write the result to the out object with println().

String userInput;
while ((userInput = stdIn.readLine()) != null) {
    out.println(userInput);
    //... 
}

You can find these lines in the code listing on the tutorial page: https://docs.oracle.com/javase/tutorial/networking/sockets/readingWriting.html

This isn't the only way of writing to a socket, but that's how the example does it and you should probably stick with that for now.