client/src/main/java/envoy/client/event/ThemeChangeEvent.java

@@ -10,16 +10,7 @@ import envoy.event.Event;
  * @author Kai S. K. Engelbart
  * @since Envoy Client v0.2-alpha
  */
-public final class ThemeChangeEvent extends Event<String> {
+public final class ThemeChangeEvent extends Event.Valueless {
 
 	private static final long serialVersionUID = 0L;
-
-	/**
-	 * Initializes a {@link ThemeChangeEvent} conveying information about the change
-	 * of the theme currently in use.
-	 *
-	 * @param theme the name of the new theme
-	 * @since Envoy Client v0.2-alpha
-	 */
-	public ThemeChangeEvent(String theme) { super(theme); }
 }

client/src/main/java/envoy/client/net/Client.java

@@ -1,20 +1,19 @@
 package envoy.client.net;
 
-import java.io.Closeable;
+import java.io.*;
-import java.io.IOException;
 import java.net.Socket;
 import java.util.concurrent.TimeoutException;
-import java.util.logging.Level;
+import java.util.logging.*;
-import java.util.logging.Logger;
 
 import envoy.client.data.*;
 import envoy.client.event.SendEvent;
 import envoy.data.*;
 import envoy.event.*;
-import envoy.event.contact.ContactOperation;
+import envoy.event.Event;
-import envoy.event.contact.UserSearchResult;
+import envoy.event.contact.*;
-import envoy.util.EnvoyLog;
+import envoy.util.*;
-import envoy.util.SerializationUtils;
+
+import dev.kske.eventbus.*;
 
 /**
  * Establishes a connection to the server, performs a handshake and delivers
@@ -29,7 +28,7 @@ import envoy.util.SerializationUtils;
  * @author Leon Hofmeister
  * @since Envoy Client v0.1-alpha
  */
-public final class Client implements Closeable {
+public final class Client implements EventListener, Closeable {
 
 	// Connection handling
 	private Socket		socket;
@@ -45,6 +44,15 @@ public final class Client implements Closeable {
 	private static final Logger			logger		= EnvoyLog.getLogger(Client.class);
 	private static final EventBus		eventBus	= EventBus.getInstance();
 
+	/**
+	 * Constructs a client and registers it as an event listener.
+	 *
+	 * @since Envoy Client v0.2-beta
+	 */
+	public Client() {
+		eventBus.registerListener(this);
+	}
+
 	/**
 	 * Enters the online mode by acquiring a user ID from the server. As a
 	 * connection has to be established and a handshake has to be made, this method
@@ -164,22 +172,14 @@ public final class Client implements Closeable {
 		// Process ProfilePicChanges
 		receiver.registerProcessor(ProfilePicChange.class, eventBus::dispatch);
 
-		// Process requests to not send any more attachments as they will not be shown to
+		// Process requests to not send any more attachments as they will not be shown
+		// to
 		// other users
 		receiver.registerProcessor(NoAttachments.class, eventBus::dispatch);
 
 		// Process group creation results - they might have been disabled on the server
 		receiver.registerProcessor(GroupCreationResult.class, eventBus::dispatch);
 
-		// Send event
-		eventBus.register(SendEvent.class, evt -> {
-			try {
-				sendEvent(evt.get());
-			} catch (final IOException e) {
-				logger.log(Level.WARNING, "An error occurred when trying to send " + evt, e);
-			}
-		});
-
 		// Request a generator if none is present or the existing one is consumed
 		if (!localDB.hasIDGenerator() || !localDB.getIDGenerator().hasNext()) requestIdGenerator();
 
@@ -219,6 +219,21 @@ public final class Client implements Closeable {
 		writeObject(new IDGeneratorRequest());
 	}
 
+	/**
+	 * Sends the value of a send event to the server.
+	 *
+	 * @param evt the send event to extract the value from
+	 * @since Envoy Client v0.2-beta
+	 */
+	@dev.kske.eventbus.Event
+	private void onSendEvent(SendEvent evt) {
+		try {
+			sendEvent(evt.get());
+		} catch (final IOException e) {
+			logger.log(Level.WARNING, "An error occurred when trying to send " + evt, e);
+		}
+	}
+
 	@Override
 	public void close() throws IOException { if (online) socket.close(); }
 

client/src/main/java/envoy/client/net/GroupMessageStatusChangeProcessor.java

@@ -4,10 +4,11 @@ import java.util.function.Consumer;
 import java.util.logging.Logger;
 
 import envoy.data.Message.MessageStatus;
-import envoy.event.EventBus;
 import envoy.event.GroupMessageStatusChange;
 import envoy.util.EnvoyLog;
 
+import dev.kske.eventbus.EventBus;
+
 /**
  * Project: <strong>envoy-client</strong><br>
  * File: <strong>GroupMessageStatusChangePocessor.java</strong><br>
@@ -25,5 +26,4 @@ public final class GroupMessageStatusChangeProcessor implements Consumer<GroupMe
 		if (evt.get().ordinal() < MessageStatus.RECEIVED.ordinal()) logger.warning("Received invalid group message status change " + evt);
 		else EventBus.getInstance().dispatch(evt);
 	}
-
 }

client/src/main/java/envoy/client/net/MessageStatusChangeProcessor.java

@@ -4,10 +4,11 @@ import java.util.function.Consumer;
 import java.util.logging.Logger;
 
 import envoy.data.Message.MessageStatus;
-import envoy.event.EventBus;
 import envoy.event.MessageStatusChange;
 import envoy.util.EnvoyLog;
 
+import dev.kske.eventbus.EventBus;
+
 /**
  * Project: <strong>envoy-client</strong><br>
  * File: <strong>MessageStatusChangeProcessor.java</strong><br>

client/src/main/java/envoy/client/net/ReceivedGroupMessageProcessor.java

@@ -6,9 +6,10 @@ import java.util.logging.Logger;
 import envoy.client.event.MessageCreationEvent;
 import envoy.data.GroupMessage;
 import envoy.data.Message.MessageStatus;
-import envoy.event.EventBus;
 import envoy.util.EnvoyLog;
 
+import dev.kske.eventbus.EventBus;
+
 /**
  * Project: <strong>envoy-client</strong><br>
  * File: <strong>ReceivedGroupMessageProcessor.java</strong><br>

client/src/main/java/envoy/client/net/ReceivedMessageProcessor.java

@@ -5,7 +5,8 @@ import java.util.function.Consumer;
 import envoy.client.event.MessageCreationEvent;
 import envoy.data.Message;
 import envoy.data.Message.MessageStatus;
-import envoy.event.EventBus;
+
+import dev.kske.eventbus.EventBus;
 
 /**
  * Project: <strong>envoy-client</strong><br>

client/src/main/java/envoy/client/ui/SceneContext.java

@@ -6,15 +6,15 @@ import java.util.logging.Level;
 
 import javafx.application.Platform;
 import javafx.fxml.FXMLLoader;
-import javafx.scene.Parent;
+import javafx.scene.*;
-import javafx.scene.Scene;
 import javafx.stage.Stage;
 
 import envoy.client.data.Settings;
 import envoy.client.event.ThemeChangeEvent;
-import envoy.event.EventBus;
 import envoy.util.EnvoyLog;
 
+import dev.kske.eventbus.*;
+
 /**
  * Manages a stack of scenes. The most recently added scene is displayed inside
  * a stage. When a scene is removed from the stack, its predecessor is
@@ -30,7 +30,7 @@ import envoy.util.EnvoyLog;
  * @author Kai S. K. Engelbart
  * @since Envoy Client v0.1-beta
  */
-public final class SceneContext {
+public final class SceneContext implements EventListener {
 
 	/**
 	 * Contains information about different scenes and their FXML resource files.
@@ -84,7 +84,7 @@ public final class SceneContext {
 	 */
 	public SceneContext(Stage stage) {
 		this.stage = stage;
-		EventBus.getInstance().register(ThemeChangeEvent.class, theme -> applyCSS());
+		EventBus.getInstance().registerListener(this);
 	}
 
 	/**
@@ -152,6 +152,9 @@ public final class SceneContext {
 		}
 	}
 
+	@Event(priority = 150, eventType = ThemeChangeEvent.class)
+	private void onThemeChange() { applyCSS(); }
+
 	/**
 	 * @param <T> the type of the controller
 	 * @return the controller used by the current scene

client/src/main/java/envoy/client/ui/StatusTrayIcon.java

@@ -8,7 +8,9 @@ import javafx.stage.Stage;
 
 import envoy.client.event.MessageCreationEvent;
 import envoy.data.Message;
-import envoy.event.EventBus;
+
+import dev.kske.eventbus.*;
+import dev.kske.eventbus.Event;
 
 /**
  * Project: <strong>envoy-client</strong><br>
@@ -18,7 +20,7 @@ import envoy.event.EventBus;
  * @author Kai S. K. Engelbart
  * @since Envoy Client v0.2-alpha
  */
-public final class StatusTrayIcon {
+public final class StatusTrayIcon implements EventListener {
 
 	/**
 	 * The {@link TrayIcon} provided by the System Tray API for controlling the
@@ -67,14 +69,7 @@ public final class StatusTrayIcon {
 		trayIcon.addActionListener(evt -> Platform.runLater(() -> { stage.setIconified(false); stage.toFront(); stage.requestFocus(); }));
 
 		// Start processing message events
-		EventBus.getInstance().register(MessageCreationEvent.class, evt -> {
+		EventBus.getInstance().registerListener(this);
-			if (displayMessages) trayIcon
-				.displayMessage(
-						evt.get().hasAttachment() ? "New " + evt.get().getAttachment().getType().toString().toLowerCase() + " message received"
-								: "New message received",
-						evt.get().getText(),
-						MessageType.INFO);
-		});
 	}
 
 	/**
@@ -94,4 +89,11 @@ public final class StatusTrayIcon {
 	 * @since Envoy Client v0.2-beta
 	 */
 	public void hide() { SystemTray.getSystemTray().remove(trayIcon); }
+
+	@Event
+	private void onMessageCreation(MessageCreationEvent evt) {
+		if (displayMessages) trayIcon
+			.displayMessage(evt.get().hasAttachment() ? "New " + evt.get().getAttachment().getType().toString().toLowerCase() + " message received"
+					: "New message received", evt.get().getText(), MessageType.INFO);
+	}
 }

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

@@ -1,7 +1,5 @@
 package envoy.client.ui.controller;
 
-import static envoy.data.Message.MessageStatus.RECEIVED;
-
 import java.awt.Toolkit;
 import java.awt.datatransfer.StringSelection;
 import java.io.*;
@@ -36,11 +34,15 @@ import envoy.client.ui.listcell.*;
 import envoy.client.util.ReflectionUtil;
 import envoy.data.*;
 import envoy.data.Attachment.AttachmentType;
+import envoy.data.Message.MessageStatus;
 import envoy.event.*;
 import envoy.event.contact.ContactOperation;
 import envoy.exception.EnvoyException;
 import envoy.util.EnvoyLog;
 
+import dev.kske.eventbus.*;
+import dev.kske.eventbus.Event;
+
 /**
  * Project: <strong>envoy-client</strong><br>
  * File: <strong>ChatSceneController.java</strong><br>
@@ -49,7 +51,7 @@ import envoy.util.EnvoyLog;
  * @author Kai S. K. Engelbart
  * @since Envoy Client v0.1-beta
  */
-public final class ChatScene implements Restorable {
+public final class ChatScene implements EventListener, Restorable {
 
 	@FXML
 	private GridPane scene;
@@ -160,6 +162,8 @@ public final class ChatScene implements Restorable {
 	 */
 	@FXML
 	private void initialize() {
+		eventBus.registerListener(this);
+
 		// Initialize message and user rendering
 		messageList.setCellFactory(MessageListCell::new);
 		chatList.setCellFactory(new ListCellFactory<>(ChatControl::new));
@@ -201,110 +205,119 @@ public final class ChatScene implements Restorable {
 				updateInfoLabel("You are offline", "info-label-warning");
 			}
 		});
+	}
 
-		// Listen to backEvents
+	@Event(eventType = BackEvent.class)
-		eventBus.register(BackEvent.class, e -> tabPane.getSelectionModel().select(Tabs.CONTACT_LIST.ordinal()));
+	private void onBackEvent() { tabPane.getSelectionModel().select(Tabs.CONTACT_LIST.ordinal()); }
 
-		// Listen to received messages
+	@Event
-		eventBus.register(MessageCreationEvent.class, e -> {
+	private void onMessageCreation(MessageCreationEvent evt) {
-			final var message = e.get();
+		final var message = evt.get();
 
-			// The sender of the message is the recipient of the chat
+		// The sender of the message is the recipient of the chat
-			// Exceptions: this user is the sender (sync) or group message (group is
+		// Exceptions: this user is the sender (sync) or group message (group is
-			// recipient)
+		// recipient)
-			final var recipientID = message instanceof GroupMessage || message.getSenderID() == localDB.getUser().getID() ? message.getRecipientID()
+		final var recipientID = message instanceof GroupMessage || message.getSenderID() == localDB.getUser().getID() ? message.getRecipientID()
-					: message.getSenderID();
+				: message.getSenderID();
-			localDB.getChat(recipientID).ifPresent(chat -> {
+		localDB.getChat(recipientID).ifPresent(chat -> {
-				chat.insert(message);
+			chat.insert(message);
-				if (chat.equals(currentChat)) {
+			if (chat.equals(currentChat)) {
-					try {
+				try {
-						currentChat.read(writeProxy);
+					currentChat.read(writeProxy);
-					} catch (final IOException e1) {
+				} catch (final IOException e1) {
-						logger.log(Level.WARNING, "Could not read current chat: ", e1);
+					logger.log(Level.WARNING, "Could not read current chat: ", e1);
-					}
+				}
-					Platform.runLater(() -> { ListViewRefresh.deepRefresh(messageList); scrollToMessageListEnd(); });
+				Platform.runLater(() -> { ListViewRefresh.deepRefresh(messageList); scrollToMessageListEnd(); });
-					// TODO: Increment unread counter for group messages with status < RECEIVED
+				// TODO: Increment unread counter for group messages with status < RECEIVED
-				} else if (message.getSenderID() != localDB.getUser().getID() && message.getStatus() == RECEIVED) chat.incrementUnreadAmount();
+			} else
+				if (message.getSenderID() != localDB.getUser().getID() && message.getStatus() == MessageStatus.RECEIVED) chat.incrementUnreadAmount();
 
-				// Move chat with most recent unread messages to the top
+			// Move chat with most recent unread messages to the top
-				Platform.runLater(() -> {
-					chats.getSource().remove(chat);
-					((ObservableList<Chat>) chats.getSource()).add(0, chat);
-
-					if (chat.equals(currentChat)) chatList.getSelectionModel().select(0);
-				});
-			});
-		});
-
-		// Listen to message status changes
-		eventBus.register(MessageStatusChange.class, e -> localDB.getMessage(e.getID()).ifPresent(message -> {
-			message.setStatus(e.get());
-			// Update UI if in current chat and the current user was the sender of the
-			// message
-			if (currentChat != null && message.getSenderID() == client.getSender().getID()) Platform.runLater(messageList::refresh);
-		}));
-
-		eventBus.register(GroupMessageStatusChange.class, e -> localDB.getMessage(e.getID()).ifPresent(groupMessage -> {
-			((GroupMessage) groupMessage).getMemberStatuses().replace(e.getMemberID(), e.get());
-
-			// Update UI if in current chat
-			if (currentChat != null && groupMessage.getRecipientID() == currentChat.getRecipient().getID()) Platform.runLater(messageList::refresh);
-		}));
-
-		// Listen to user status changes
-		eventBus.register(UserStatusChange.class,
-				e -> chats.getSource()
-					.stream()
-					.filter(c -> c.getRecipient().getID() == e.getID())
-					.findAny()
-					.map(Chat::getRecipient)
-					.ifPresent(u -> { ((User) u).setStatus(e.get()); Platform.runLater(() -> ListViewRefresh.deepRefresh(chatList)); }));
-
-		// Listen to contacts changes
-		eventBus.register(ContactOperation.class, e -> {
-			final var contact = e.get();
-			switch (e.getOperationType()) {
-				case ADD:
-					if (contact instanceof User) localDB.getUsers().put(contact.getName(), (User) contact);
-					final var chat = contact instanceof User ? new Chat(contact) : new GroupChat(client.getSender(), contact);
-					Platform.runLater(() -> ((ObservableList<Chat>) chats.getSource()).add(0, chat));
-					break;
-				case REMOVE:
-					Platform.runLater(() -> chats.getSource().removeIf(c -> c.getRecipient().equals(contact)));
-					break;
-			}
-		});
-
-		// Disable attachment button if server says attachments will be filtered out
-		eventBus.register(NoAttachments.class, e -> {
 			Platform.runLater(() -> {
-				attachmentButton.setDisable(true);
+				chats.getSource().remove(chat);
-				voiceButton.setDisable(true);
+				((ObservableList<Chat>) chats.getSource()).add(0, chat);
-				final var alert = new Alert(AlertType.ERROR);
+
-				alert.setTitle("No attachments possible");
+				if (chat.equals(currentChat)) chatList.getSelectionModel().select(0);
-				alert.setHeaderText("Your current server does not support attachments.");
-				alert.setContentText("If this is unplanned, please contact your server administrator.");
-				alert.showAndWait();
 			});
 		});
+	}
 
-		eventBus.register(GroupCreationResult.class, e -> Platform.runLater(() -> { newGroupButton.setDisable(!e.get()); }));
+	@Event
-
+	private void onMessageStatusChange(MessageStatusChange evt) {
-		eventBus.register(ThemeChangeEvent.class, e -> {
+		localDB.getMessage(evt.getID()).ifPresent(message -> {
-			settingsButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("settings", DEFAULT_ICON_SIZE)));
+		message.setStatus(evt.get());
-			voiceButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("microphone", DEFAULT_ICON_SIZE)));
+		// Update UI if in current chat and the current user was the sender of the
-			attachmentButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("attachment", DEFAULT_ICON_SIZE)));
+		// message
-			DEFAULT_ATTACHMENT_VIEW_IMAGE = IconUtil.loadIconThemeSensitive("attachment_present", 20);
+		if (currentChat != null && message.getSenderID() == client.getSender().getID()) Platform.runLater(messageList::refresh);
-			attachmentView.setImage(isCustomAttachmentImage ? attachmentView.getImage() : DEFAULT_ATTACHMENT_VIEW_IMAGE);
-			messageSearchButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("search", DEFAULT_ICON_SIZE)));
-			clientProfilePic.setImage(IconUtil.loadIconThemeSensitive("user_icon", 43));
-			chatList.setCellFactory(new ListCellFactory<>(ChatControl::new));
-			messageList.setCellFactory(MessageListCell::new);
-			if (currentChat.getRecipient() instanceof User) recipientProfilePic.setImage(IconUtil.loadIconThemeSensitive("user_icon", 43));
-			else recipientProfilePic.setImage(IconUtil.loadIconThemeSensitive("group_icon", 43));
 		});
 	}
 
+	@Event
+	private void onGroupMessageStatusChange(GroupMessageStatusChange evt) {
+		localDB.getMessage(evt.getID()).ifPresent(groupMessage -> {
+			((GroupMessage) groupMessage).getMemberStatuses().replace(evt.getMemberID(), evt.get());
+
+		// Update UI if in current chat
+		if (currentChat != null && groupMessage.getRecipientID() == currentChat.getRecipient().getID()) Platform.runLater(messageList::refresh);
+		});
+	}
+
+	@Event
+	private void onUserStatusChange(UserStatusChange evt) {
+		chats.getSource()
+			.stream()
+			.filter(c -> c.getRecipient().getID() == evt.getID())
+			.findAny()
+			.map(Chat::getRecipient)
+			.ifPresent(u -> { ((User) u).setStatus(evt.get()); Platform.runLater(() -> ListViewRefresh.deepRefresh(chatList)); });
+	}
+
+	@Event
+	private void onContactOperation(ContactOperation operation) {
+		final var contact = operation.get();
+		switch (operation.getOperationType()) {
+			case ADD:
+				if (contact instanceof User) localDB.getUsers().put(contact.getName(), (User) contact);
+				final var chat = contact instanceof User ? new Chat(contact) : new GroupChat(client.getSender(), contact);
+				Platform.runLater(() -> ((ObservableList<Chat>) chats.getSource()).add(0, chat));
+				break;
+			case REMOVE:
+				Platform.runLater(() -> chats.getSource().removeIf(c -> c.getRecipient().equals(contact)));
+				break;
+		}
+	}
+
+	@Event(eventType = NoAttachments.class)
+	private void onNoAttachments() {
+		Platform.runLater(() -> {
+			attachmentButton.setDisable(true);
+			voiceButton.setDisable(true);
+			final var alert = new Alert(AlertType.ERROR);
+			alert.setTitle("No attachments possible");
+			alert.setHeaderText("Your current server does not support attachments.");
+			alert.setContentText("If this is unplanned, please contact your server administrator.");
+			alert.showAndWait();
+		});
+	}
+
+	@Event
+	private void onGroupCreationResult(GroupCreationResult result) { Platform.runLater(() -> newGroupButton.setDisable(!result.get())); }
+
+	@Event(eventType = ThemeChangeEvent.class)
+	private void onThemeChange() {
+		settingsButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("settings", DEFAULT_ICON_SIZE)));
+		voiceButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("microphone", DEFAULT_ICON_SIZE)));
+		attachmentButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("attachment", DEFAULT_ICON_SIZE)));
+		DEFAULT_ATTACHMENT_VIEW_IMAGE = IconUtil.loadIconThemeSensitive("attachment_present", 20);
+		attachmentView.setImage(isCustomAttachmentImage ? attachmentView.getImage() : DEFAULT_ATTACHMENT_VIEW_IMAGE);
+		messageSearchButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("search", DEFAULT_ICON_SIZE)));
+		clientProfilePic.setImage(IconUtil.loadIconThemeSensitive("user_icon", 43));
+		chatList.setCellFactory(new ListCellFactory<>(ChatControl::new));
+		messageList.setCellFactory(MessageListCell::new);
+		if (currentChat.getRecipient() instanceof User) recipientProfilePic.setImage(IconUtil.loadIconThemeSensitive("user_icon", 43));
+		else recipientProfilePic.setImage(IconUtil.loadIconThemeSensitive("group_icon", 43));
+	}
+
 	/**
 	 * Initializes all {@code SystemCommands} used in {@code ChatScene}.
 	 *

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

@@ -1,26 +1,21 @@
 package envoy.client.ui.controller;
 
-import java.util.function.Consumer;
+import java.util.logging.*;
-import java.util.logging.Level;
-import java.util.logging.Logger;
 
 import javafx.application.Platform;
 import javafx.fxml.FXML;
 import javafx.scene.control.*;
 import javafx.scene.control.Alert.AlertType;
 
-import envoy.client.event.BackEvent;
+import envoy.client.event.*;
-import envoy.client.event.SendEvent;
+import envoy.client.ui.listcell.*;
-import envoy.client.ui.listcell.ContactControl;
-import envoy.client.ui.listcell.ListCellFactory;
 import envoy.data.User;
 import envoy.event.ElementOperation;
-import envoy.event.EventBus;
+import envoy.event.contact.*;
-import envoy.event.contact.ContactOperation;
-import envoy.event.contact.UserSearchRequest;
-import envoy.event.contact.UserSearchResult;
 import envoy.util.EnvoyLog;
 
+import dev.kske.eventbus.*;
+
 /**
  * Provides a search bar in which a user name (substring) can be entered. The
  * users with a matching name are then displayed inside a list view. A
@@ -39,7 +34,7 @@ import envoy.util.EnvoyLog;
  * @author Maximilian Käfer
  * @since Envoy Client v0.1-beta
  */
-public class ContactSearchTab {
+public class ContactSearchTab implements EventListener {
 
 	@FXML
 	private TextArea searchBar;
@@ -48,26 +43,29 @@ public class ContactSearchTab {
 	private ListView<User> userList;
 
 	private Alert alert = new Alert(AlertType.CONFIRMATION);
-
 	private User currentlySelectedUser;
 
-	private final Consumer<ContactOperation> handler = e -> {
-		final var contact = e.get();
-		if (e.getOperationType() == ElementOperation.ADD) Platform.runLater(() -> {
-			userList.getItems().remove(contact);
-			if (currentlySelectedUser != null && currentlySelectedUser.equals(contact) && alert.isShowing()) alert.close();
-		});
-	};
-
 	private static final EventBus	eventBus	= EventBus.getInstance();
 	private static final Logger		logger		= EnvoyLog.getLogger(ChatScene.class);
 
 	@FXML
 	private void initialize() {
+		eventBus.registerListener(this);
 		userList.setCellFactory(new ListCellFactory<>(ContactControl::new));
-		eventBus.register(UserSearchResult.class,
+	}
-				response -> Platform.runLater(() -> { userList.getItems().clear(); userList.getItems().addAll(response.get()); }));
+
-		eventBus.register(ContactOperation.class, handler);
+	@Event
+	private void onUserSearchResult(UserSearchResult result) {
+		Platform.runLater(() -> { userList.getItems().clear(); userList.getItems().addAll(result.get()); });
+	}
+
+	@Event
+	private void onContactOperation(ContactOperation operation) {
+		final var contact = operation.get();
+		if (operation.getOperationType() == ElementOperation.ADD) Platform.runLater(() -> {
+			userList.getItems().remove(contact);
+			if (currentlySelectedUser != null && currentlySelectedUser.equals(contact) && alert.isShowing()) alert.close();
+		});
 	}
 
 	/**

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

@@ -8,20 +8,15 @@ import javafx.fxml.FXML;
 import javafx.scene.control.*;
 import javafx.scene.layout.HBox;
 
-import envoy.client.data.Chat;
+import envoy.client.data.*;
-import envoy.client.data.Context;
+import envoy.client.event.*;
-import envoy.client.data.LocalDB;
+import envoy.client.ui.listcell.*;
-import envoy.client.event.BackEvent;
+import envoy.data.*;
-import envoy.client.event.SendEvent;
-import envoy.client.ui.listcell.ContactControl;
-import envoy.client.ui.listcell.ListCellFactory;
-import envoy.data.Contact;
-import envoy.data.Group;
-import envoy.data.User;
-import envoy.event.EventBus;
 import envoy.event.GroupCreation;
 import envoy.util.Bounds;
 
+import dev.kske.eventbus.*;
+
 /**
  * Provides a group creation interface. A group name can be entered in the text
  * field at the top. Available users (local chat recipients) are displayed
@@ -38,7 +33,7 @@ import envoy.util.Bounds;
  * @author Maximilian Käfer
  * @since Envoy Client v0.1-beta
  */
-public class GroupCreationTab {
+public class GroupCreationTab implements EventListener {
 
 	@FXML
 	private Button createButton;

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

@@ -1,9 +1,7 @@
 package envoy.client.ui.controller;
 
-import java.util.logging.Level;
+import java.util.logging.*;
-import java.util.logging.Logger;
 
-import javafx.application.Platform;
 import javafx.fxml.FXML;
 import javafx.geometry.Insets;
 import javafx.scene.control.*;
@@ -11,13 +9,12 @@ import javafx.scene.control.Alert.AlertType;
 import javafx.scene.image.ImageView;
 
 import envoy.client.data.ClientConfig;
-import envoy.client.ui.IconUtil;
+import envoy.client.ui.*;
-import envoy.client.ui.Startup;
 import envoy.data.LoginCredentials;
-import envoy.event.EventBus;
 import envoy.event.HandshakeRejection;
-import envoy.util.Bounds;
+import envoy.util.*;
-import envoy.util.EnvoyLog;
+
+import dev.kske.eventbus.*;
 
 /**
  * Project: <strong>envoy-client</strong><br>
@@ -28,7 +25,7 @@ import envoy.util.EnvoyLog;
  * @author Maximilian K&auml;fer
  * @since Envoy Client v0.1-beta
  */
-public final class LoginScene {
+public final class LoginScene implements EventListener {
 
 	@FXML
 	private TextField userTextField;
@@ -60,7 +57,6 @@ public final class LoginScene {
 	private boolean registration = false;
 
 	private static final Logger			logger		= EnvoyLog.getLogger(LoginScene.class);
-	private static final EventBus		eventBus	= EventBus.getInstance();
 	private static final ClientConfig	config		= ClientConfig.getInstance();
 
 	@FXML
@@ -68,7 +64,7 @@ public final class LoginScene {
 		connectionLabel.setText("Server: " + config.getServer() + ":" + config.getPort());
 
 		// Show an alert after an unsuccessful handshake
-		eventBus.register(HandshakeRejection.class, e -> Platform.runLater(() -> { new Alert(AlertType.ERROR, e.get()).showAndWait(); }));
+		EventBus.getInstance().registerListener(this);
 
 		logo.setImage(IconUtil.loadIcon("envoy_logo"));
 
@@ -119,4 +115,7 @@ public final class LoginScene {
 		logger.log(Level.INFO, "The login process has been cancelled. Exiting...");
 		System.exit(0);
 	}
+
+	@Event
+	private void onHandshakeRejection(HandshakeRejection evt) { new Alert(AlertType.ERROR, evt.get()).showAndWait(); }
 }

client/src/main/java/envoy/client/ui/settings/BugReportPane.java

@@ -7,9 +7,10 @@ import javafx.scene.input.InputEvent;
 import envoy.client.event.SendEvent;
 import envoy.client.util.IssueUtil;
 import envoy.data.User;
-import envoy.event.EventBus;
 import envoy.event.IssueProposal;
 
+import dev.kske.eventbus.EventBus;
+
 /**
  * This class offers the option for users to submit a bug report. Only the title
  * of a bug is needed to be sent.

client/src/main/java/envoy/client/ui/settings/GeneralSettingsPane.java

@@ -1,12 +1,12 @@
 package envoy.client.ui.settings;
 
-import javafx.scene.control.ComboBox;
+import javafx.scene.control.*;
-import javafx.scene.control.Tooltip;
 
 import envoy.client.data.SettingsItem;
 import envoy.client.event.ThemeChangeEvent;
 import envoy.data.User.UserStatus;
-import envoy.event.EventBus;
+
+import dev.kske.eventbus.EventBus;
 
 /**
  * Project: <strong>envoy-client</strong><br>
@@ -44,7 +44,7 @@ public final class GeneralSettingsPane extends SettingsPane {
 		combobox.setTooltip(new Tooltip("Determines the current theme Envoy will be displayed in."));
 		combobox.setValue(settings.getCurrentTheme());
 		combobox.setOnAction(
-				e -> { settings.setCurrentTheme(combobox.getValue()); EventBus.getInstance().dispatch(new ThemeChangeEvent(combobox.getValue())); });
+				e -> { settings.setCurrentTheme(combobox.getValue()); EventBus.getInstance().dispatch(new ThemeChangeEvent()); });
 		getChildren().add(combobox);
 
 		final var statusComboBox = new ComboBox<UserStatus>();

client/src/main/java/envoy/client/ui/settings/UserSettingsPane.java

@@ -1,31 +1,27 @@
 package envoy.client.ui.settings;
 
-import java.io.ByteArrayInputStream;
+import java.io.*;
-import java.io.File;
-import java.io.IOException;
 import java.nio.file.Files;
-import java.util.logging.Level;
+import java.util.logging.*;
-import java.util.logging.Logger;
 
 import javafx.event.EventHandler;
 import javafx.geometry.Pos;
 import javafx.scene.Cursor;
 import javafx.scene.control.*;
 import javafx.scene.control.Alert.AlertType;
-import javafx.scene.image.Image;
+import javafx.scene.image.*;
-import javafx.scene.image.ImageView;
 import javafx.scene.input.InputEvent;
 import javafx.scene.layout.HBox;
 import javafx.stage.FileChooser;
 
 import envoy.client.event.SendEvent;
-import envoy.client.ui.IconUtil;
+import envoy.client.ui.*;
-import envoy.client.ui.SceneContext;
 import envoy.client.ui.custom.ProfilePicImageView;
 import envoy.data.User;
 import envoy.event.*;
-import envoy.util.Bounds;
+import envoy.util.*;
-import envoy.util.EnvoyLog;
+
+import dev.kske.eventbus.EventBus;
 
 /**
  * Project: <strong>envoy-client</strong><br>

client/src/main/java/module-info.java

@@ -7,19 +7,20 @@
  * @author Maximilian Käfer
  * @since Envoy Client v0.1-beta
  */
-module envoy {
+module envoy.client {
 
-	requires transitive envoy.common;
+	requires envoy.common;
-	requires transitive java.desktop;
+	requires java.desktop;
-	requires transitive java.logging;
+	requires java.logging;
-	requires transitive java.prefs;
+	requires java.prefs;
 	requires javafx.controls;
 	requires javafx.fxml;
 	requires javafx.base;
 	requires javafx.graphics;
 
-	opens envoy.client.ui to javafx.graphics, javafx.fxml;
+	opens envoy.client.ui to javafx.graphics, javafx.fxml, dev.kske.eventbus;
-	opens envoy.client.ui.controller to javafx.graphics, javafx.fxml, envoy.client.util;
+	opens envoy.client.ui.controller to javafx.graphics, javafx.fxml, envoy.client.util, dev.kske.eventbus;
 	opens envoy.client.ui.custom to javafx.graphics, javafx.fxml;
 	opens envoy.client.ui.settings to envoy.client.util;
+	opens envoy.client.net to dev.kske.eventbus;
 }

common/pom.xml

@@ -12,11 +12,24 @@
 		<version>0.1-beta</version>
 	</parent>
 
+	<repositories>
+		<repository>
+			<id>kske-repo</id>
+			<url>https://kske.dev/maven-repo</url>
+		</repository>
+	</repositories>
+
 	<dependencies>
+		<dependency>
+			<groupId>dev.kske</groupId>
+			<artifactId>event-bus</artifactId>
+			<version>0.0.3</version>
+		</dependency>
 		<dependency>
 			<groupId>org.junit.jupiter</groupId>
 			<artifactId>junit-jupiter-engine</artifactId>
 			<version>5.5.2</version>
+			<scope>test</scope>
 		</dependency>
 	</dependencies>
 	<build>

common/src/main/java/envoy/event/Event.java

@@ -2,7 +2,13 @@ package envoy.event;
 
 import java.io.Serializable;
 
+import dev.kske.eventbus.IEvent;
+
 /**
+ * This class serves as a convenience base class for all events. It implements
+ * the {@link IEvent} interface and provides a generic value. For events without
+ * a value there also is {@link envoy.event.Event.Valueless}.
+ * <p>
  * Project: <strong>envoy-common</strong><br>
  * File: <strong>Event.java</strong><br>
  * Created: <strong>04.12.2019</strong><br>
@@ -11,7 +17,7 @@ import java.io.Serializable;
  * @param <T> the type of the Event
  * @since Envoy v0.2-alpha
  */
-public abstract class Event<T> implements Serializable {
+public abstract class Event<T> implements IEvent, Serializable {
 
 	protected final T value;
 

common/src/main/java/envoy/event/EventBus.java

@@ -1,82 +0,0 @@
-package envoy.event;
-
-import java.util.*;
-import java.util.function.Consumer;
-
-/**
- * This class handles events by allowing event handlers to register themselves
- * and then be notified about certain events dispatched by the event bus.<br>
- * <br>
- * The event bus is a singleton and can be used across the entire application to
- * guarantee the propagation of events.<br>
- * <br>
- * Project: <strong>envoy-common</strong><br>
- * File: <strong>EventBus.java</strong><br>
- * Created: <strong>04.12.2019</strong><br>
- *
- * @author Kai S. K. Engelbart
- * @since Envoy v0.2-alpha
- */
-public final class EventBus {
-
-	/**
-	 * Contains all event handler instances registered at this event bus as values
-	 * mapped to by their supported event classes.
-	 */
-	private Map<Class<? extends Event<?>>, List<Consumer<Event<?>>>> handlers = new HashMap<>();
-
-	/**
-	 * The singleton instance of this event bus that is used across the
-	 * entire application.
-	 */
-	private static EventBus eventBus = new EventBus();
-
-	/**
-	 * This constructor is not accessible from outside this class because a
-	 * singleton instance of it is provided by the {@link EventBus#getInstance()}
-	 * method.
-	 */
-	private EventBus() {}
-
-	/**
-	 * @return the singleton instance of the event bus
-	 * @since Envoy v0.2-alpha
-	 */
-	public static EventBus getInstance() { return eventBus; }
-
-	/**
-	 * Registers an event handler to be notified when an
-	 * event of a certain type is dispatched.
-	 *
-	 * @param <T>        the type of event values to notify the handler about
-	 * @param eventClass the class which the event handler is subscribing to
-	 * @param handler    the event handler to register
-	 * @since Envoy v0.2-alpha
-	 */
-	public <T extends Event<?>> void register(Class<T> eventClass, Consumer<T> handler) {
-		if (!handlers.containsKey(eventClass)) handlers.put(eventClass, new ArrayList<>());
-		handlers.get(eventClass).add((Consumer<Event<?>>) handler);
-	}
-
-	/**
-	 * Dispatches an event to every event handler subscribed to it.
-	 *
-	 * @param event the {@link Event} to dispatch
-	 * @since Envoy v0.2-alpha
-	 */
-	public void dispatch(Event<?> event) {
-		handlers.keySet()
-			.stream()
-			.filter(event.getClass()::equals)
-			.map(handlers::get)
-			.flatMap(List::stream)
-			.forEach(h -> h.accept(event));
-	}
-
-	/**
-	 * @return a map of all event handler instances currently registered at this
-	 *         event bus with the event classes they are subscribed to as keys
-	 * @since Envoy v0.2-alpha
-	 */
-	public Map<Class<? extends Event<?>>, List<Consumer<Event<?>>>> getHandlers() { return handlers; }
-}

common/src/main/java/module-info.java

@@ -16,4 +16,5 @@ module envoy.common {
 	exports envoy.event.contact;
 
 	requires transitive java.logging;
+	requires transitive dev.kske.eventbus;
 }

server/src/main/java/module-info.java

@@ -16,5 +16,4 @@ module envoy.server {
 	requires transitive java.persistence;
 	requires transitive java.sql;
 	requires transitive org.hibernate.orm.core;
-
 }