implement chatServer class

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

@@ -1,15 +1,26 @@
 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 void main(String[] args) {
-        // TODO: Create a ServerSocket
+    private static final  UserManager userManager = new UserManager();
+    private static final  int port = 9000;
 
-        // TODO: In an infinite loop:
-        //  accept an incoming client connection
-        //  make a new thread running ClientSession for each user.
+    public static void main(String[] args) throws IOException {
+
+        try( ServerSocket serverSocket = new ServerSocket(port)){
+            System.out.println("Server started on port " + port);
+            while(true){
+                Socket clientSocket = serverSocket.accept();
+                Thread clientThread = new Thread(new ClientSession(clientSocket,userManager));
+                clientThread.start();
+            }
+        }
+        catch (IOException e){
+            System.out.println("server error: " + e.getMessage());
+        }
     }
 }

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

@@ -14,6 +14,7 @@ public class ClientSession implements Runnable {
     public ClientSession(Socket socket, UserManager userManager) {
         // TODO : Create an ObjectOutputStream from socket.getOutputStream()
         //         and an ObjectInputStream from socket.getInputStream().
+
     }
 
     @Override