Added event system

+ Event interface for defining event objects
+ EventHandler interface for defining event handlers
+ EventBus singleton class for managing event handlers and dispatching
events

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

@@ -0,0 +1,16 @@
+package envoy.client.event;
+
+/**
+ * Project: <strong>envoy-clientChess</strong><br>
+ * File: <strong>Event.javaEvent.java</strong><br>
+ * Created: <strong>04.12.2019</strong><br>
+ * 
+ * @author Kai S. K. Engelbart
+ */
+public interface Event<T> {
+
+	/**
+	 * @return the data associated with this event
+	 */
+	T get();
+}

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

@@ -0,0 +1,32 @@
+package envoy.client.event;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+/**
+ * Project: <strong>envoy-clientChess</strong><br>
+ * File: <strong>EventBus.javaEvent.java</strong><br>
+ * Created: <strong>04.12.2019</strong><br>
+ * 
+ * @author Kai S. K. Engelbart
+ */
+public class EventBus {
+
+	private static EventBus eventBus;
+
+	private List<EventHandler> handlers = new ArrayList<>();
+
+	private EventBus() {}
+
+	public EventBus getInstance() {
+		if (eventBus == null) eventBus = new EventBus();
+		return eventBus;
+	}
+
+	public void register(EventHandler... handlers) { this.handlers.addAll(Arrays.asList(handlers)); }
+
+	public void dispatch(Event<?> event) { handlers.stream().filter(h -> h.supports().contains(event.getClass())).forEach(h -> h.handle(event)); }
+
+	public List<EventHandler> getHandlers() { return handlers; }
+}

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

@@ -0,0 +1,25 @@
+package envoy.client.event;
+
+import java.util.Set;
+
+/**
+ * Project: <strong>envoy-clientChess</strong><br>
+ * File: <strong>EventHandler.javaEvent.java</strong><br>
+ * Created: <strong>04.12.2019</strong><br>
+ * 
+ * @author Kai S. K. Engelbart
+ */
+public interface EventHandler {
+
+	/**
+	 * Consumes an event dispatched by the event bus.
+	 * 
+	 * @param event The event dispatched by the event bus, only of supported type
+	 */
+	void handle(Event<?> event);
+
+	/**
+	 * @return A set of classes this class is supposed to handle in events
+	 */
+	Set<Class<? extends Event<?>>> supports();
+}