ChatServer completed.

src/main/java/com/university/chat/Server/ChatServer.java

@@ -1,15 +1,30 @@
 package com.university.chat.Server;
 
+import java.io.IOException;
+import java.net.ServerSocket;
+import java.net.Socket;
+
 public class ChatServer {
-    // TODO: declare a single shared UserManager instance (static final)
-    //         This MUST be shared by all ClientSession threads so that
-    //         broadcasting and private messaging work correctly.
+    public static final UserManager userManager = new UserManager();
 
     public static void main(String[] args) {
-        // TODO: Create a ServerSocket
+        int port = 8080;
 
-        // TODO: In an infinite loop:
-        //  accept an incoming client connection
-        //  make a new thread running ClientSession for each user.
+        try (ServerSocket serverSocket = new ServerSocket(port)) {
+            //for catching multiple clients at the same time
+            while (true) {
+                //waiting for the client and catches it when it connects
+                Socket socket = serverSocket.accept();
+
+                //building a client session to get the socket
+                ClientSession clientSession = new ClientSession(socket, userManager);
+
+                //building a thread to this client
+                Thread SoketThread = new Thread(clientSession);
+                SoketThread.start();
+            }
+        } catch (IOException e) {
+            System.out.println(e.getMessage());
+        }
     }
 }