src/main/java/chat/ChatClient.java

@@ -40,16 +40,30 @@ public class ChatClient {
         // TODO: create socket connection to host:port
         // TODO: initialize output stream (PrintWriter)
         // TODO: initialize input stream (BufferedReader)
+        socket = new Socket(host, port);
+        out = new PrintWriter(socket.getOutputStream(), true);
+        in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
     }
 
     private void readUserInputAndSend() throws IOException {
         // TODO: read continuously from console
         // TODO: send each input line to server
+        String input;
+        while ((input = consoleReader.readLine()) != null) {
+            out.println(input);
+        }
     }
 
     private void cleanup() {
         // TODO: close socket safely
         // TODO: release resources
+        try {
+            if (socket != null && !socket.isClosed()) {
+                socket.close();
+            }
+        } catch (IOException e) {
+            System.err.println("Error closing socket: " + e.getMessage());
+        }
     }
 
     public static void main(String[] args) {

src/main/java/chat/ChatServer.java

@@ -42,17 +42,31 @@ public class ChatServer {
         // step 1: iterate through connectedClients safely
         // step 2: skip the sender client
         // step 3: send message to remaining clients using sendMessage
+        synchronized (connectedClients) {
+            for (ClientHandler client : connectedClients) {
+                if (client != sender) {
+                    client.sendMessage(message);
+                }
+            }
+        }
     }
 
     public void broadcastSystemMessage(String message) {
         // step 1: iterate through all connected clients
         // step 2: send system message to each client
+        synchronized (connectedClients) {
+            for (ClientHandler client : connectedClients) {
+                client.sendMessage(message);
+            }
+        }
     }
 
     public void removeClient(ClientHandler clientHandler) {
         // step 1: remove client from connectedClients set
         // step 2: retrieve username from clientHandler
         // step 3: broadcast system message about user leaving
+        connectedClients.remove(clientHandler);
+        broadcastSystemMessage("[System] " + clientHandler.getUsername() + " left the chat.");
     }
 
     public static void main(String[] args) {

src/main/java/chat/MessageListener.java

@@ -15,5 +15,13 @@ public class MessageListener implements Runnable {
     public void run() {
         // TODO: continuously read messages from server
         // TODO: print received messages immediately
+        try {
+            String message;
+            while ((message = inputReader.readLine()) != null) {
+                System.out.println(message);
+            }
+        } catch (IOException e) {
+            System.err.println("Connection lost: " + e.getMessage());
+        }
     }
 }