init project

src/main/java/chat/ChatServer.java

@@ -0,0 +1,69 @@
+package chat;
+
+import java.io.IOException;
+import java.net.ServerSocket;
+import java.net.Socket;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
+public class ChatServer {
+
+    private final int port;
+    private final Set<ClientHandler> connectedClients;
+    private final ExecutorService threadPool;
+
+    public ChatServer(int port) {
+        this.port = port;
+        this.connectedClients = Collections.synchronizedSet(new HashSet<>());
+        this.threadPool = Executors.newCachedThreadPool();
+    }
+
+    public void start() {
+        try (ServerSocket serverSocket = new ServerSocket(port)) {
+            System.out.println("Chat server started on port " + port);
+
+            while (true) {
+                Socket clientSocket = serverSocket.accept();
+                ClientHandler clientHandler = new ClientHandler(clientSocket, this);
+                connectedClients.add(clientHandler);
+                threadPool.execute(clientHandler);
+            }
+        } catch (IOException e) {
+            System.err.println("Server error: " + e.getMessage());
+        } finally {
+            threadPool.shutdown();
+        }
+    }
+
+    public void broadcast(String message, ClientHandler sender) {
+        // step 1: iterate through connectedClients safely
+        // step 2: skip the sender client
+        // step 3: send message to remaining clients using sendMessage
+    }
+
+    public void broadcastSystemMessage(String message) {
+        // step 1: iterate through all connected clients
+        // step 2: send system message to each client
+    }
+
+    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
+    }
+
+    public static void main(String[] args) {
+        int port = 12345;
+        if (args.length > 0) {
+            try {
+                port = Integer.parseInt(args[0]);
+            } catch (NumberFormatException e) {
+                System.err.println("Invalid port. Using default: " + port);
+            }
+        }
+        new ChatServer(port).start();
+    }
+}