implement serverListener class

src/main/java/com/university/chat/Client/ServerListener.java

@@ -1,18 +1,34 @@
 package com.university.chat.Client;
 
+import com.university.chat.Common.ChatMessage;
+import com.university.chat.Common.FileMessage;
+
+import java.io.ObjectInputStream;
+import java.net.Socket;
+
 public class ServerListener implements Runnable{
-    // TODO: store the ObjectInputStream from the user socket
+
-    //          (this should be the same input stream the
+    private final ObjectInputStream in;
-    //           chatClient created when connecting)
+
+    public ServerListener(ObjectInputStream in) {
+        this.in = in;
+    }
 
     @Override
     public void run() {
         try {
-            // TODO: In an infinite loop read objects from the server
+            
-            //   - if it's a ChatMessage  -> print "<sender>: <content>"
+            while (true) {
-            //   - if it's a FileMessage  -> print that a file was received
+                Object obj = in.readObject();
-            //                               (filename + sender), it's already
+                if (obj instanceof ChatMessage msg) {
-            //                               saved to disk by the server.
+                    System.out.println(msg.getSender() + ": " + msg.getContent());
+                }
+                else if (obj instanceof FileMessage file) {
+                    System.out.println("[File received] '" + file.getFilename()
+                            + "' from " + file.getSender());
+                }
+            }
+
         } catch (Exception e){
             System.out.println("Disconnected from server");
         }