Implemented GroupChat as subclass of Chat and adjusted calls of such

src/main/java/envoy/client/data/Chat.java

@@ -2,7 +2,6 @@ package envoy.client.data;
 
 import java.io.IOException;
 import java.io.Serializable;
-import java.time.LocalDateTime;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Objects;
@@ -10,7 +9,6 @@ import java.util.Objects;
 import envoy.client.net.WriteProxy;
 import envoy.data.*;
 import envoy.data.Message.MessageStatus;
-import envoy.event.GroupMessageStatusChange;
 import envoy.event.MessageStatusChange;
 
 /**
@@ -26,11 +24,10 @@ import envoy.event.MessageStatusChange;
  * @author Kai S. K. Engelbart
  * @since Envoy Client v0.1-alpha
  */
-public final class Chat implements Serializable {
+public class Chat implements Serializable {
 
-	private final Contact		recipient;
-	private final Contact		sender;
-	private final List<Message>	messages	= new ArrayList<>();
+	protected final Contact			recipient;
+	protected final List<Message>	messages	= new ArrayList<>();
 
 	private static final long serialVersionUID = 1L;
 
@@ -40,13 +37,10 @@ public final class Chat implements Serializable {
 	 * Saves the Messages in the corresponding chat at that Point.
 	 *
 	 * @param recipient the user who receives the messages
-	 * @param sender    the user who is logged in as sender on this instance of
-	 *                  envoy.client
 	 * @since Envoy Client v0.1-alpha
 	 */
-	public Chat(Contact recipient, Contact sender) {
+	public Chat(Contact recipient) {
 		this.recipient	= recipient;
-		this.sender		= sender;
 	}
 
 	@Override
@@ -87,17 +81,6 @@ public final class Chat implements Serializable {
 	public void read(WriteProxy writeProxy) throws IOException {
 		for (int i = messages.size() - 1; i >= 0; --i) {
 			final Message m = messages.get(i);
-			if(m.getClass().equals(GroupMessage.class)) {
-				GroupMessage g = (GroupMessage) m;
-				if (g.getSenderID() != sender.getID()) {
-					if (g.getMemberStatuses().get(sender.getID()) == MessageStatus.READ) break;
-					else {
-						g.getMemberStatuses().replace(sender.getID(), MessageStatus.READ);
-						writeProxy.writeMessageStatusChange(
-								new GroupMessageStatusChange(g.getID(), MessageStatus.READ, LocalDateTime.now(), sender.getID()));
-					}
-				}
-			}else {
 			if (m.getSenderID() == recipient.getID()) if (m.getStatus() == MessageStatus.READ) break;
 			else {
 				m.setStatus(MessageStatus.READ);
@@ -105,7 +88,6 @@ public final class Chat implements Serializable {
 			}
 		}
 	}
-	}
 
 	/**
 	 * @return {@code true} if the newest message received in the chat doesn't have

src/main/java/envoy/client/data/GroupChat.java

@@ -0,0 +1,51 @@
+package envoy.client.data;
+
+import java.io.IOException;
+import java.time.LocalDateTime;
+
+import envoy.client.net.WriteProxy;
+import envoy.data.Contact;
+import envoy.data.GroupMessage;
+import envoy.data.Message.MessageStatus;
+import envoy.data.User;
+import envoy.event.GroupMessageStatusChange;
+
+/**
+ * Project: <strong>envoy-client</strong><br>
+ * File: <strong>GroupChat.java</strong><br>
+ * Created: <strong>05.07.2020</strong><br>
+ * 
+ * @author Maximilian K&auml;fer
+ * @since Envoy Client v0.1-beta
+ */
+public class GroupChat extends Chat {
+
+	private final User sender;
+
+	private static final long serialVersionUID = 1L;
+
+	/**
+	 * @param sender    the user sending the messages
+	 * @param recipient the user who receives the messages
+	 * @since Envoy Client v0.1-beta
+	 */
+	public GroupChat(User sender, Contact recipient) {
+		super(recipient);
+		this.sender = sender;
+	}
+
+	@Override
+	public void read(WriteProxy writeProxy) throws IOException {
+		for (int i = messages.size() - 1; i >= 0; --i) {
+			final GroupMessage g = (GroupMessage) messages.get(i);
+			if (g.getSenderID() != sender.getID()) {
+				if (g.getMemberStatuses().get(sender.getID()) == MessageStatus.READ) break;
+				else {
+					g.getMemberStatuses().replace(sender.getID(), MessageStatus.READ);
+					writeProxy
+						.writeMessageStatusChange(new GroupMessageStatusChange(g.getID(), MessageStatus.READ, LocalDateTime.now(), sender.getID()));
+				}
+			}
+		}
+	}
+}

src/main/java/envoy/client/data/LocalDB.java

@@ -82,7 +82,11 @@ public abstract class LocalDB {
 				getChat(contact.getID()).ifPresent(chat -> { ((User) chat.getRecipient()).setStatus(((User) contact).getStatus()); });
 
 		// Create missing chats
-		user.getContacts().stream().filter(u -> !u.equals(user) && getChat(u.getID()).isEmpty()).map(u -> new Chat(u, user)).forEach(chats::add);
+		user.getContacts()
+			.stream()
+			.filter(c -> !c.equals(user) && getChat(c.getID()).isEmpty())
+			.map(c -> c instanceof User ? new Chat(c) : new GroupChat(user, c))
+			.forEach(chats::add);
 	}
 
 	/**

src/main/java/envoy/client/ui/controller/ChatScene.java

@@ -17,9 +17,7 @@ import javafx.scene.input.KeyCode;
 import javafx.scene.input.KeyEvent;
 import javafx.scene.paint.Color;
 
-import envoy.client.data.Chat;
-import envoy.client.data.LocalDB;
-import envoy.client.data.Settings;
+import envoy.client.data.*;
 import envoy.client.event.MessageCreationEvent;
 import envoy.client.net.Client;
 import envoy.client.net.WriteProxy;
@@ -143,7 +141,7 @@ public final class ChatScene implements Restorable {
 			switch (e.getOperationType()) {
 				case ADD:
 					localDB.getUsers().put(contact.getName(), contact);
-					localDB.getChats().add(new Chat(contact, client.getSender()));
+					localDB.getChats().add(contact instanceof User ? new Chat(contact) : new GroupChat(client.getSender(), contact));
 					Platform.runLater(() -> userList.getItems().add(contact));
 					break;
 				case REMOVE: