diff --git a/solutions/java/src/LLDRunner.java b/solutions/java/src/LLDRunner.java
index f08e330..62cb026 100644
--- a/solutions/java/src/LLDRunner.java
+++ b/solutions/java/src/LLDRunner.java
@@ -20,7 +20,7 @@
 import onlineshopping.OnlineShoppingServiceDemo;
 import onlinestockbrokeragesystem.StockBrokerageSystemDemo;
 import parkinglot.ParkingLotDemo;
-import pubsubsystem.PubSubDemo;
+import pubsubsystem.PubSubSystemDemo;
 import restaurantmanagementsystem.RestaurantManagementDemo;
 import ridesharingservice.RideSharingServiceDemo;
 import snakeandladdergame.SnakeAndLadderDemo;
@@ -58,7 +58,7 @@ public static void main(String[] args) {
 //        OnlineShoppingServiceDemo.run();
 //        StockBrokerageSystemDemo.run();
 //        ParkingLotDemo.run();
-//        PubSubDemo.run();
+//        PubSubSystemDemo.run();
 //        RestaurantManagementDemo.run();
 //        RideSharingServiceDemo.run();
 //        SnakeAndLadderDemo.run();
diff --git a/solutions/java/src/pubsubsystem/ConcreteSubscriber.java b/solutions/java/src/pubsubsystem/PrintSubscriber.java
similarity index 71%
rename from solutions/java/src/pubsubsystem/ConcreteSubscriber.java
rename to solutions/java/src/pubsubsystem/PrintSubscriber.java
index f2c6164..84b08bc 100644
--- a/solutions/java/src/pubsubsystem/ConcreteSubscriber.java
+++ b/solutions/java/src/pubsubsystem/PrintSubscriber.java
@@ -1,9 +1,9 @@
 package pubsubsystem;
 
-public class ConcreteSubscriber implements Subscriber {
+public class PrintSubscriber implements Subscriber {
     private final String name;
 
-    public ConcreteSubscriber(String name) {
+    public PrintSubscriber(String name) {
         this.name = name;
     }
 
diff --git a/solutions/java/src/pubsubsystem/PubSubDemo.java b/solutions/java/src/pubsubsystem/PubSubDemo.java
deleted file mode 100644
index 29f9da9..0000000
--- a/solutions/java/src/pubsubsystem/PubSubDemo.java
+++ /dev/null
@@ -1,41 +0,0 @@
-package pubsubsystem;
-
-public class PubSubDemo {
-    public static void run() {
-        PubSubSystem pubSubSystem = new PubSubSystem();
-
-        // Create topics
-        pubSubSystem.createTopic("Topic1");
-        pubSubSystem.createTopic("Topic2");
-
-        // Create subscribers
-        Subscriber subscriber1 = new ConcreteSubscriber("Subscriber1");
-        Subscriber subscriber2 = new ConcreteSubscriber("Subscriber2");
-        Subscriber subscriber3 = new ConcreteSubscriber("Subscriber3");
-
-        // Subscribe to topics
-        pubSubSystem.subscribe("Topic1", subscriber1);
-        pubSubSystem.subscribe("Topic1", subscriber2);
-        pubSubSystem.subscribe("Topic2", subscriber2);
-        pubSubSystem.subscribe("Topic2", subscriber3);
-
-        // Create publishers
-        Publisher publisher1 = new Publisher(pubSubSystem.getTopics().get("Topic1"));
-        Publisher publisher2 = new Publisher(pubSubSystem.getTopics().get("Topic2"));
-
-        // Publish messages
-        publisher1.publish(new Message("Message1 for Topic1"));
-        publisher1.publish(new Message("Message2 for Topic1"));
-        publisher2.publish(new Message("Message1 for Topic2"));
-
-        // Unsubscribe from a topic
-        pubSubSystem.unsubscribe("Topic1", subscriber2);
-
-        // Publish more messages
-        publisher1.publish(new Message("Message3 for Topic1"));
-        publisher2.publish(new Message("Message2 for Topic2"));
-
-        // Shutdown the system
-        pubSubSystem.shutdown();
-    }
-}
diff --git a/solutions/java/src/pubsubsystem/PubSubSystem.java b/solutions/java/src/pubsubsystem/PubSubSystem.java
deleted file mode 100644
index a814b61..0000000
--- a/solutions/java/src/pubsubsystem/PubSubSystem.java
+++ /dev/null
@@ -1,44 +0,0 @@
-package pubsubsystem;
-
-import java.util.Map;
-import java.util.concurrent.ConcurrentHashMap;
-import java.util.concurrent.ExecutorService;
-import java.util.concurrent.Executors;
-
-public class PubSubSystem {
-    private final Map<String, Topic> topics = new ConcurrentHashMap<>();
-    private final ExecutorService executorService = Executors.newFixedThreadPool(10);
-
-    public void createTopic(String topicName) {
-        topics.putIfAbsent(topicName, new Topic(topicName));
-    }
-
-    public void subscribe(String topicName, Subscriber subscriber) {
-        Topic topic = topics.get(topicName);
-        if (topic != null) {
-            topic.addSubscriber(subscriber);
-        }
-    }
-
-    public void unsubscribe(String topicName, Subscriber subscriber) {
-        Topic topic = topics.get(topicName);
-        if (topic != null) {
-            topic.removeSubscriber(subscriber);
-        }
-    }
-
-    public void publish(String topicName, Message message) {
-        Topic topic = topics.get(topicName);
-        if (topic != null) {
-            executorService.submit(() -> topic.publish(message));
-        }
-    }
-
-    public void shutdown() {
-        executorService.shutdown();
-    }
-
-    public Map<String, Topic> getTopics() {
-        return topics;
-    }
-}
diff --git a/solutions/java/src/pubsubsystem/PubSubSystemDemo.java b/solutions/java/src/pubsubsystem/PubSubSystemDemo.java
new file mode 100644
index 0000000..39788c6
--- /dev/null
+++ b/solutions/java/src/pubsubsystem/PubSubSystemDemo.java
@@ -0,0 +1,40 @@
+package pubsubsystem;
+
+public class PubSubSystemDemo {
+    public static void run() {
+        // Create topics
+        Topic topic1 = new Topic("Topic1");
+        Topic topic2 = new Topic("Topic2");
+
+        // Create publishers
+        Publisher publisher1 = new Publisher();
+        Publisher publisher2 = new Publisher();
+
+        // Create subscribers
+        Subscriber subscriber1 = new PrintSubscriber("Subscriber1");
+        Subscriber subscriber2 = new PrintSubscriber("Subscriber2");
+        Subscriber subscriber3 = new PrintSubscriber("Subscriber3");
+
+        publisher1.registerTopic(topic1);
+        publisher2.registerTopic(topic2);
+
+        // Subscribe to topics
+        topic1.addSubscriber(subscriber1);
+        topic1.addSubscriber(subscriber2);
+        topic2.addSubscriber(subscriber2);
+        topic2.addSubscriber(subscriber3);
+
+        // Publish messages
+        publisher1.publish(topic1, new Message("Message1 for Topic1"));
+        publisher1.publish(topic1, new Message("Message2 for Topic1"));
+        publisher2.publish(topic2, new Message("Message1 for Topic2"));
+
+
+        // Unsubscribe from a topic
+        topic1.removeSubscriber(subscriber2);
+
+        // Publish more messages
+        publisher1.publish(topic1, new Message("Message3 for Topic1"));
+        publisher2.publish(topic2, new Message("Message2 for Topic2"));
+    }
+}
diff --git a/solutions/java/src/pubsubsystem/Publisher.java b/solutions/java/src/pubsubsystem/Publisher.java
index c62a339..2b72930 100644
--- a/solutions/java/src/pubsubsystem/Publisher.java
+++ b/solutions/java/src/pubsubsystem/Publisher.java
@@ -1,13 +1,24 @@
 package pubsubsystem;
 
+import java.util.HashSet;
+import java.util.Set;
+
 public class Publisher {
-    private final Topic topic;
+    private final Set<Topic> topics;
+
+    public Publisher() {
+        this.topics = new HashSet<>();
+    }
 
-    public Publisher(Topic topic) {
-        this.topic = topic;
+    public void registerTopic(Topic topic) {
+        topics.add(topic);
     }
 
-    public void publish(Message message) {
+    public void publish(Topic topic, Message message) {
+        if(!topics.contains(topic)) {
+            System.out.println("This publisher can't publish to topic: " + topic.getName());
+            return;
+        }
         topic.publish(message);
     }
 }