title: Sockets and ServerSockets Server/Client GUI Chat Program
body: <p>I'm trying to learn how sockets and ServerSockets work in Java so I tried to do a Chat Server but at the same time using threading to handle each client. I think I need some fresh eyes on my code because I have no idea why it's not working. The program starts but the client does not connect and the is not created.  I'm fairly certain something is wrong in my client class but I'm not certain what needs to be fixed.  Any help at all, even just a link to a helpful resource, would be very appreciated. Thanks. </p>
  
  <p>Server Code</p>
  
  <pre><code>     package chatbox.server;
  
          import static java.lang.System.out;
  
          import java.io.IOException;
          import java.io.InputStream;
          import java.io.InputStreamReader;
          import java.io.OutputStream;
          import java.io.PrintStream;
          import java.net.ServerSocket;
          import java.net.Socket;
          import java.util.ArrayList;
          import java.util.Scanner;
  
  
       public class Server {
  
  
      public final static int DEFAULT_PORT = 5000;
  
      private ServerSocket socket;
      private ArrayList&lt;Socket&gt; clients;
  
  
      public Server(int port) throws IOException {
          System.out.println("Server is now online");
          System.out.println("port: " + port);
          this.socket = new ServerSocket(port);
          System.out.println("Listening socket established");
          System.out.println("Waiting for connections...");
          this.clients = new ArrayList&lt;Socket&gt;();
  
  
          while (true) {
              try {
                  final Socket connection = this.socket.accept();
                  this.clients.add(connection);
  
  
                  Runnable incomingMsg = new Runnable() {
                      private InputStream inputStream = connection.getInputStream();
                      private InputStreamReader reader = new InputStreamReader(
                              inputStream);
                      private Scanner scanner = new Scanner(reader);
  
                      @Override
                      public void run() {
                          while (true) {
                              if (scanner.hasNextLine()) {
                                  String msg = scanner.nextLine();
                                  System.out.println("Handling message: \"" + msg
                                          + "\"");
                                  notifyAllConnections(msg);
                              }
                          }
                      }
  
                  };
  
                  Thread thread = new Thread(incomingMsg);
  
  
                  thread.setUncaughtExceptionHandler(new Thread.UncaughtExceptionHandler() {
  
                      @Override
                      public void uncaughtException(Thread thread, Throwable exc) {
                          try {
                              connection.close();
                          } catch (IOException e1) {
  
                              e1.printStackTrace();
                          } finally {
                              clients.remove(connection);
                              System.out.println("Removed connection");
                          }
  
                      }
                  });
                  thread.start();
                  System.out.println("Added new connection");
              } catch (IOException exc) {
  
                  System.out
                          .println("Error occurred.");
              }
          }
      }
  
      protected void notifyAllConnections(String msg) {
          for (Socket sock : this.clents) {
              try {
                  OutputStream out = sock.getOutputStream();
                  PrintStream printer = new PrintStream(out);
                  printer.println(msg);
                  printer.flush();
              } catch (IOException exc) {
                  System.out.println("Message was not fully broadcast");
              }
  
          }
      }
  
      public static void main(String[] args) {
          try {
              Server server = new Server(
                      Server.DEFAULT_PORT);
          } catch (IOException exc) {
              System.out
                      .println("Could not create the server socket.");
              exc.printStackTrace();
              String servername = "localhost";
              try {
                  new Client(servername, 5000);
              } catch (Exception ex) {
                  out.println("Error" + ex.getMessage());
  
              }
          }
      }
      }
  </code></pre>
  
  <p>Client Code</p>
  
  <pre><code>     package chatbox.client
  
          import java.awt.event.ActionListener;
  
          import javax.swing.JFrame;
          import java.io.*;
          import java.util.*;
          import java.net.*;
          import javax.swing.*;
          import java.awt.*;
          import java.awt.event.*;
          import static java.lang.System.out;
  
          public class Client extends JFrame {
  
      private PrintWriter pw;
      private Scanner scanner;
      private JPanel chatAndSend;
      private JTextArea chatWindow;
      private JScrollPane mainScroll;
      private JTextArea chatText;
      private JScrollPane miniScroll;
      private JButton send;
      private Socket client;
  
      public Client(String servername, int port) throws Exception {
  
          this.client = new Socket(servername, port);
          this.scanner = new Scanner(new InputStreamReader(
                  this.client.getInputStream()));
          this.pw = new PrintWriter(this.client.getOutputStream());
  
          makeGUI();
          new MessagesThread().start();
  
      }
  
      public void makeGUI() {
          setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          getContentPane().setLayout(new BorderLayout());
          this.chatWindow = new JTextArea(10, 20);
          this.chatWindow.setEditable(false);
          this.chatWindow.setLineWrap(true);
          this.mainScroll = new JScrollPane(chatWindow,
                  JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED,
                  JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
          this.add(this.mainScroll, BorderLayout.NORTH);
          this.chatAndSend = new JPanel();
          this.chatAndSend.setLayout(new FlowLayout());
          this.chatText = new JTextArea(1, 1);
          this.chatText.setLineWrap(true);
          this.miniScroll = new JScrollPane(chatText,
                  JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED,
                  JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
          this.chatAndSend.add(this.miniScroll);
          this.send = new JButton();
          this.send.setText("SEND");
          this.send.addActionListener(new ActionListener() {
              public void actionPerformed(ActionEvent event) {
                  pw.println(chatText.getText());
                  pw.flush();
              }
          });
          this.chatAndSend.add(this.send);
          this.add(this.chatAndSend, BorderLayout.SOUTH);
          this.setVisible(true);
          this.pack();
      }
  
      class MessagesThread extends Thread {
          public void run() {
              String line;
              try {
                  while (true) {
                      line = scanner.nextLine();
                      chatWindow.append(line + "\n");
                  }
              } catch (Exception exception) {
                  System.out.println(exception.getMessage());
              }
          }
      }
      }
  </code></pre>